Smith, Curtis W. LITHOLOGIC, GEOPHYSICAL, AND
PALEOENVIRONMENTAL FRAMEWORK OF RELICT INLET
CHANNEL-FILL AND ADJACENT FACIES: NORTH CAROLINA
OUTER BANKS. (Under the direction of Dr. David J. Mallinson and
Stephen J. Culver) Department of Geological Sciences, November 2006.
The geophysical, sedimentological and chronostratigraphic framework of the
Outer Banks barrier island system (North Carolina, USA) is being defined. Previous
researchers have reconstructed a complex evolutionary history of this barrier island
system, including periods of partial barrier island collapse followed by barrier island
reformation and transgression with extensive inlet formation. The focus of the present
project is to define the extent, characteristics, and ages of relict inlets and subsequent
channel-fill facies.
Over 100 km of high-resolution ground penetrating radar (GPR) data were
acquired between Oregon and Ocracoke Inlets. GPR facies were characterized using
shore-parallel GPR transects and 3-D surveys at selected locations. GPR data were
correlated to sediments collected in 27 vibracores to provide the regional shallow (<8 m)
stratigraphic framework. Lithologic and microfossil data defined four facies allowing for
inferences of multiple paleoenvironments. Organic and carbonate material have been
dated using AMS ’‘*0 analyses and quartz sand units were dated using optically-
stimulated luminescence (OSL) analyses.
GPR data reveal several previously undocumented relict inlet channels, as well as
determining that inlet-fill constitutes a minimum of 40% to a maximum of 70% of the
shallow (<8 m below ground surface) geologic framework. The data reveal multiple
sequences of fill within complex inlets. Channel-fill sands are characterized by
prominent clinoform packages, sometimes bounded by erosional surfaces, indicating
variable sediment transport directions generally from the NE and NW within the majority
of each complex inlet. Along the southernmost edge of most complex inlets, the data
reveal shoal development and migration from the SE and SW late in the closure of the
inlets. Three types of paleochannels (migrating complex inlet, non-migrating/single inlet,
and non-migrating/complex inlet) were classified based on geometry and fill-patterns.
Two OSL age estimates from vibracores taken at the site of the original breach of Oregon
Inlet (known to occur in 1846 A.D.) produced correct ages on channel-fill sand. This
represents a “proof of concept” that inlet-fill sands can provide accurate OSL ages
documenting time of inlet activity. Use of OSL on channel-fill sand produces accurate
ages that can be used to constrain inlet activity on the Outer Banks. OSL age estimates
on channel-fill sands indicate a period of increased inlet activity along the Outer Banks
from ~0.55 to 0.275 ka (2-sigma range).
LITHOLOGIC, GEOPHYSICAL, AND PALEOENVIRONMENTAL
FRAMEWORK OF RELICT INLET CHANNEL-FILL AND ADJACENT
FACIES: NORTH CAROLINA OUTER BANKS
A Thesis
Presented to
the Faculty of the Department of Geological Sciences
East Carolina University
In Partial Fulfillment
Of the requirements for the Degree
Master of Science in Geology
By
Curtis W. Smith
November 2006
^ &0 C#
LITHOLOGIC, GEOPHYSICAL, AND PALEOENVIRONMENTAL
FRAMEWORK OF RELICT INLET CHANNEL-FILL AND ADJACENT
FACIES: NORTH CAROLINA OUTER BANKS
By
Curtis W. Smith
Approved By:
DIRECTOR OF THESIS
Dr. David J. Mallinson
DIRECTOR OF THESIS
r.- Stephen J. Culver
COMMITTEE MEMBER
r. Stanley R. Riggs ^ '
COMMITTEE MEMBER C
Dr. Jessè E. McNinch
CHAIR OF THE
DEPARTMENT OF
GEOLOGICAL SCIENCES
DEAN OF THE
GRADUATE SCHOOL
ACKNOWLEDGEMENTS
First and foremost, I would not be where I am today without Mom, Dad, Philip,
and my entire family. Their love and support has driven me from the beginning. A
special thank you to Drs. D. Mallinson, S. Culver, S. Riggs, and J. McNinch for their
guidance during my graduate career. This project would not have been possible without
the assistance of Jim Watson, Dorothea Ames, Ron Crowson, and my fellow ECU and
UPenn graduate students in the field and laboratory. I would also like to thank Shannon
Mahan for assisting with data processing. This project is part of the North Carolina
Coastal Geology Cooperative and was funded by the USGS Cooperative Agreement
award 02ERAG0044, and donors to the American Chemical Society - Petroleum
Research Fund.
TABLE OF CONTENTS
List of Tables viii
List of Figures ix
INTRODUCTION 1
Purpose of Study 1
Objectives 4
Previous Works 6
Regional Geologic Setting 6
Historic Inlet Activity 11
Ground Penetrating Radar (GPR) 14
Sedimentological Characterization 17
Foraminiferal Characterization 22
METHODOLOGY 27
Ground Penetrating Radar Data Acquisition and Analysis 27
Vibracore Acquisition and Analysis 28
Lithofacies Analysis 31
Biofacies Analysis 33
Age Analyses 35
Radiocarbon Dating 35
Luminescence Dating 36
RESULTS 40
IV
Geophysical Data 40
Radar Facies Description 40
3-D GPR Surveys 51
Pea Island; S-Curves 52
Salvo Complex Inlet 56
Kinnakeet Complex Inlet 56
Avon Complex Inlet 61
Buxton Inlet 70
Isabel Inlet 70
Ocracoke Island 78
Lithofacies Description 82
Sand (S) 82
Shelly Sand (S(sheiiy)) 82
Shelly Gravelly Sand (gS(sheiiy)) 86
Gravelly Sand (gS) 87
Muddy Sand (mS) 90
Massively Bedded Sand (S(mas)) 92
Heavy Mineral Laminated Sand (S(iam)) 94
Rooted Sand (S(rtd)) 96
Shelly Sandy Gravel (sG(sheiiy)) 99
Mud (M) 101
Massive Mud (M(mas)) 101
V
Sandy Mud (sM) 103
Peat(P) 105
Correlation of Radar Facies and Lithofacies 107
Rodanthe Non-migrating/Complex Inlet 107
Salvo Complex Inlet Ill
Kinnakeet Complex Inlet 118
Avon Complex Inlet 118
Ocracoke Island 126
Foraminiferal Assemblages 134
Biofacies 1 136
Biofacies 2 136
Biofacies 3 139
Biofacies 4 139
Correlation of Radar Facies, Lithofacies, and Biofacies 140
Radar-Litho-BioFacies 1 (RLBF-1) - Low Energy Estuarine
Environment/Estuarine Shoal 140
Radar-Litho-BioFacies 2 (RLBF-2) 142
Overwash (RLBF 2-a) 142
Inlet Channel (RLBF 2-b) 142
Low Energy Estuarine Environmentt/Flood Tide Delta
(RLBF 2-c) 142
Radar-Litho-BioFacies 3 (RLBF-3) 143
Inlet Channel (RLBF 3-a) 143
VI
Overwash (RLBF 3-b) 143
Low Energy Estuarine Environment/Flood Tide Delta
(RLBF 3-c) 144
Radar-Litho-BioFacies 4 (RLBF-4) 144
Inlet Channel (RLBF 4-a) 144
Overwash (RLBF 4-b) 145
High Energy Estuarine Environment/Inlet Channel
(RLBF 4-c) 145
Low Energy Estuarine Environment/Flood Tide Delta
(RLBF 4-d) 145
Age Data 146
Radiocarbon Age Estimates 146
Luminescence Age Estimates 148
DISCUSSION 152
Classification of Inlets 152
Spatial Distribution of Inlet and Overwash Facies 157
Historical Inlets 159
Oregon Inlet 167
Pea Island: S-Curves Region 171
Rodanthe Non-Migrating/Complex Inlet 174
Salvo Complex Inlet 178
Kinnakeet Complex Inlet 183
Avon Complex Inlet 190
Isabel Inlet 194
vii
Ocracoke Island 196
Summary of Holocene Geologic Evolution 206
Correlation of Inlet Activity to Holocene Climatic Events 211
Implications for Continued Development along the Outer Banks 214
SUMMARY AND CONCLUSIONS 216
REFERENCES 219
APPENDIX A: Grain Size Analysis Results 231
APPENDIX B: Raw Counts of Foraminifera Specimens 250
APPENDIX C: Alphabetical List of Foraminifera Taxa Included in the Cluster Analysis
with References to Original Publications and Figures 252
APPENDIX D: Individual Value Plots of Equivalent Dose for Vibracores and
Histograms Plotting Number of Measurements Vs. Equivalent Dose for Each OSL
Sample 256
APPENDIX E: Summary of Radar-Litho-Biofacies Data, Biofacies Data, Lithologic
Core Illustrations, Ground Penetrating Radar Data, Paleoenvironmental Interpretations,
and Age Estimates for Each Vibracore Acquired 280
APPENDIX F: Transformed Abundance Data of Foraminifera Assemblages 296
vin
LIST OF TABLES
1. Table summarizes historic inlets between Oregon Inlet and Ocracoke Inlet. Data
are from Fisher (1962) and G. Ballance (personal Communication, 2006). Table
is modified from Smith (2004). Approximate locations based on historical maps
and records 12
2. Table summarizes vibracore data acquired for this study. Dates collected,
locations, penetrations, and recoveries for each vibracore are shown 30
3. Summary table of lithofacies encountered in this study. Characteristic properties
are provided for each lithofacies 83
4. Foraminiferal occurrence (O), constancy (C), and biofacies fidelity (BF) values
for biofacies defined by cluster analysis. Boxed values indicate values for C>6
and BF>5 137
5. Table summarizes radar, litho- (LF), and bio-facies data (BF). Correlation of
these parameters resulted in four Radar-Litho-Bio Facies (RLBF) and ten sub-
facies used in making paleoenvironmental interpretations. Average mean grain
size values are bracketed. Sorting values P, M, MW, and W represent poorly.
moderately, moderately well, and well, respectively 141
6. AMS '"^C age estimates are shown. ''^C Calibration is based on Stuiver and
Reimer(1993) 147
7. Table summarizes OSL age estimates and laboratory notes are provided 149
IX
LIST OF FIGURES
1. Color contour image of eastern North Carolina from LIDAR survey data
(www.NCfloodmaps.com). The map illustrates the regional geographic features
and areas discussed in this study 2
2. Map illustrating the location of underlying paleofluvial valleys in North Carolina
(Riggs et al., 1995) 8
3. Map showing the paleo-topography of the Pleistocene drainage systems underling
the Outer Banks (Mallinson et al., in review) 10
4. Illustration shows the surface environments and sub-environments common to
barrier islands (Godfrey and Godfrey, 1976) 18
5. Photograph shows the setup for GPR data acquisition. Data were acquired by
towing the GPR antenna at approximately 2 miles per hour with a Polaris two-
seater ATV. The passenger monitored the readout and collected field notes 29
6. Photograph shows the setup for vibracore acquisition. A 4 m high tripod
stabilized the core pipe during penetration and retrieval 32
7. Legend for Radar Facies and sub-facies encountered during this study. Two
major facies are defined. The Inlet Radar Facies contains three distinct sub-facies
and two unique sub-facies comprise the Overwash Radar Facies. Explanations
are provided for distinetive characteristics for each sub-facies. Areas containing
indiscernible (attenuated) data are classified with gray color and active inlets with
black color 41
8. NC Highway-12 GPR data summary for the Outer Banks from Oregon Inlet to
Ocracoke Inlet. Data are presented as colored boxes oriented shore-parallel.
Multiple regions can be distinguished as inlet-dominated (blue, red, and orange)
and overwash-dominated (green and yellow). Bathymetric data for Pamlico
Sound are shown (http ://www.ngdc.noaa. gov/mgg/coastal/coastal .him 1 ) 42
X
9. Summary of radar facies identified in NC Highway-12 GPR data from Oregon
Inlet to the Salvo region. Data are presented as colored blocks oriented shore-
parallel. Approximate locations of historic inlets (Fisher, 1962) are shown as
white boxes. Bathymetric data for Pamlico Sound are provided
(http://www.ngdc.noaa.gov/mgg/coastal/coastal.htmn. The Rodanthe Non-
Migrating/Complex Inlet and the Salvo Complex Inlet were targeted for closer
evaluation using vibracores, age dating, foraminifera, and 3-D GPR surveys 43
10. Summary of radar facies identified in NC Highway-12 GPR data from the Salvo
region to Cape Hatteras. Data are presented as colored boxes oriented shore-
parallel. Approximate locations of historic inlets (Fisher, 1962) are shown as
white boxes. Bathymetric data for Pamlico Sound are provided
(http://www.ngdc.noaa.gov/mgg/coastal/coastal.html). The Kinnakeet Complex
Inlet and the Avon Complex Inlet were targeted for closer evaluation using
vibracores, age dating, foraminifera, and 3-D GPR surveys 44
11. Summary of radar facies identified in NC Highway-12 GPR data from Cape
Hatteras to Ocracoke Inlet. Data are presented as colored blocks oriented shore-
parallel. Approximate locations of historic inlets (Fisher, 1962; G. Ballance,
personal communication, 2006) are indicated by white squares. Conflicting
records of locations of historic inlets exist for Ocracoke Island. Bathymetric data
for Pamlico Sound are provided
(http://www.ngdc.noaa.gov/mgg/coastal/coastal.html) 45
12. Pie chart illustrates the distribution of radar facies and sub-facies occurrence
from Oregon Inlet to Ocracoke Inlet 46
13. Plot shows the average shore parallel distance of each Radar Facies encountered
in GPR data from Oregon Inlet to Ocracoke Inlet 49
14. A 1998 DOQQ (USGS) shows the Pea Island: S-Curves region directly north of
Rodanthe. The site of the eastern (pink) and western (green) 3-D GPR surveys
and vibracore ChicIn-05-Sl (black dot) are shown. Interpretations of the NC
Highway-12 GPR data are summarized in the multi-colored blocks paralleling the
island. 3D data reveal overwash channels/tidal creeks incised into a peat
platform. This area is characterized by overwash channel and overwash flat/peat
platform radar sub-facies. The approximate location of Chickinaccomock Inlet
(Fisher, 1962) is indicated by the white square 53
15. The eastern 3-D GPR survey acquired in the overwash dominated Pea Island: S-
Curves region north of Rodanthe is 8 m wide, 170 m long, and 5 m deep. The
surface at 1.1 m (shown) reveals a peat platform (continuous high amplitude
reflection). The GPR signal becomes attenuated beneath this horizon 54
XI
16. The western 3-D GPR survey acquired in the overwash dominated Pea Island: S-
Curves region north of Rodanthe islO m wide, 200 m long, and 4 m deep. The
surface at 1.1 m (shown) reveals a peat platform (eontinuous high amplitude
reflection). The GPR signal becomes attenuated beneath this horizon 55
17. Photograph shows the location of the 3-D GPR survey at the Salvo Day
Use Area. Eighty-four transects, 120 m were acquired in an open, grassy field
ideal for 3-D GPR data acquisition. The Salvo Complex Inlet underlies this
area 57
18. A 1998 DOQQ (USGS) shows the Salvo Day Use Area directly south of the
town of Salvo. The site of the 3-D GPR survey is shown in pink. The GPR
transect shown in Fig. 19 is the yellow line. Interpretations of the NC Highway-12
GPR data are summarized in the multi-colored data paralleling the island 58
19. Processed GPR data (top panel) and interpretations (bottom panel, red) made on
GPR data acquired from shore-parallel transects on NC Highway-12 reveal the
geometry of the Salvo Complex Inlet underlying southern Salvo and the Salvo
Day Use area (Fig. 18). Clinoforms are dipping at 3-5°to the south for the
majority of the area and then to the north at the southern extent of the complex
inlet. The location of the 3-D GPR survey conducted at the Salvo Day Use area is
shown in gray coloration. Vertical exaggeration = 70x 59
20. 3-D GPR survey acquired within the Salvo Complex Inlet is 83 m wide, 120 m
long, and 6 m deep. The surface at 1.12 m (shown) is characterized by at least 2
different sequences of fill based on the strike of clinoform packages indicative of
varying directions of sediment transport (shown with green arrows) from the NE
andNW 60
21. A 1998 DOQQ (USGS) shows the Kinnakeet region. The sites of two 3-D GPR
surveys are represented as green boxes on the island. The GPR transect shown in
Fig. 22 occurs as a yellow line. Radar sub-facies based upon the NC Highway-12
GPR data are summarized in the multi-colored data paralleling the island.
Locations of 3 vibracores acquired within the Kinnakeet Complex Inlet are
indicated 62
22. Processed GPR data (top panel) and interpretations (bottom panel, red) made on
GPR data acquired from shore-parallel transects on NC Highway-12 reveal the
geometry of the Kinnakeet Complex Inlet underlying the Kinnakeet region (Fig.
21). Clinoforms are dipping at 3-5°to the south and then to the north at the
southern portion of the complex inlet. The locations of two 3-D GPR surveys
conducted in the region are shown in gray coloration. Vertical exaggeration =
30x 63
23. The 3-D GPR surveys within the Kinnakeet Complex Inlet were conducted
between the primary (ridge to the left) and secondary (ridge to the right) man-
made barrier dune ridges. Tracks left by the Polaris ATV in the sand and grasses
allowed for straight transects and accurate 1 m spacing 64
24. This 3-D GPR survey acquired on the northern edge of the Kinnakeet Complex
Inlet is 21 m wide, 200 m long, and 5 m deep (Figs. 21, 22). The surface at 2.12
m (shown) is characterized by NE/SW strike and SE dipping clinoforms
appearing as high amplitude reflections. These features are interpreted as
probable recurved spits associated with the northern edge of the complex inlet ..65
25. This 3-D GPR survey acquired within the Kinnakeet Complex Inlet is 40 m wide,
85 m long, and 5 m deep (Figs. 21, 22). The surface at 1.37 m (shown) is
characterized by slightly NE/SW strike and SE dipping clinoforms appearing as
high amplitude reflections. These features indicate sediment transport from the
NW during the closing stages of the complex inlet 66
26. A 2003 DOQQ (USGS) shows the town of Avon. The 3-D GPR survey was
conducted in July 2005 and is shown in pink. NC Highway-12 GPR data are
summarized in the multi-colored data paralleling the island. The Avon region is
dominated by the presence of several migrating complex inlets including the
Avon Complex Inlet 67
27. A 2003 DOQQ (USGS) shows the town of Avon. The 3-D GPR survey was
conducted in July 2005 and is shown in pink. Avon is a wide and has not
historically had inlet activity (Fisher, 1962). The use of GPR has revealed that the
region is underlain by a massive relict complex inlet 68
28. Processed GPR data (top panel) and interpretations (bottom panel, red) made on
GPR data acquired from shore-parallel transects on NC Highway-12 reveal the
geometry of the Avon Complex Inlet underlying Avon (Fig. 26). Clinoforms are
dipping at 3-5°to the south for the majority of the area and then to the north at the
southern extent of the complex inlet. The 3-D GPR survey was conducted in the
region shown by gray coloration. Vertical exaggeration = 35x 69
29. Photograph of the 3-D GPR survey within the area containing the Avon Complex
Inlet. The survey was conducted on bulldozed lots within a housing
development 71
30. The 3-D GPR survey acquired within the Avon Complex Inlet is 20 m wide, 80 m
long, and 7 m deep. The surface at 1.61 m (shown) is characterized by aNW/SE
striking and W/SW dipping clinoform package. These features indicate sediment
transport from the E/NE during the closing stages of the complex inlet 72
Xlll
31. A 1998 DOQQ (USGS) shows historic Buxton and Chacandepeco Inlets north of
Cape Harteras. The site of the 3-D GPR survey conducted in July 2005 is shown
in green. NC Highway-12 GPR data are summarized in the multi-colored data
paralleling the island. Buxton Inlet opened during the Ash Wednesday storm of
1962 and was artificially closed in early 1963. Chacandepeco Inlet was open
from pre-1585 to -1672 (Fisher, 1962) 73
32. 400 m long, and 4 m deep (Fig. 31). The surface at 1.06 m (shown) is
characterized by a NE/SW striking and SE dipping clinoform package over the
northern most -150 m and indiscernible data occurs over the remainder of the
surface. This artificially closed inlet has similar channel-fill sequences as
naturally closed inlets 74
33. A 2003 DOQQ (USGS) shows Harteras Village and the site of the 2003 Isabel
Inlet. The site of the 3-D GPR survey conducted in July 2005 is shown by the
green rectangle on NC Highway-12. NC Highway-12 GPR data are summarized
in the multi-colored data paralleling the island. The site of Isabel Inlet has been
opened several times historically and is classified as a non-migrating/complex
inlet 75
34. A 2003 DOQQ (USGS) shows Harteras Village and the site of the 2003 Isabel
Inlet. The site of the 3-D GPR survey conducted in July 2005 is shown by the
green rectangle overlying the inlet. NC Highway-12 GPR data are summarized in
the multi-colored data paralleling the island. The site of Isabel Inlet has been
opened several times historically and is classified as a non-migrating/complex
inlet 76
35. 3-D GPR survey acquired at the site of the 2003 Isabel Inlet is 9 m wide, 850 m
long, and 4 m deep. The surface at 1.98 m (shown) is characterized by three main
channels (green shading) eroded through the remnant peat platform (horizontal
reflections). This region has historically been opened several times historically
and is classified as a non-migrating/complex inlet 77
36. A 1998 DOQQ (USGS) shows Ocracoke Island, Harteras Inlet, and Ocracoke
Inlet. Approximate locations of historic inlets are in white boxes and the 3-D
GPR survey site is shown as the green box on the island. NC Highway-12 GPR
radar sub-facies data are summarized in the multi-colored data paralleling the
island. Contradictory historic inlet approximate locations for Old Harteras and
Wells Creek Inlets are shown 79
37. A 1998 DOQQ shows the approximate location (red) of Wells Creek Inlet
according to Fisher (1962). The 3-D GPR survey site is shown in green. NC
Highway-12 GPR radar sub-facies data are summarized in the multi-colored
boxes paralleling the island 80
XIV
38. The 3-D GPR survey acquired immediately to the northeast of the approximate
location of Wells Creek Inlet according toFisher (1962) on Ocracoke Island is 13
m wide, 215 m long, and 5 m deep. The surface at 0.66 m (shown) is
characterized by chaotic data with a shallow overwash channel around 150-175 m
on the NE end of the cube. Shallow channel geometries incising into horizontal
reflections are typical of the overwash facies 81
39. Series of 1998 DOQQ aerial photographs (USGS) show the locations of 27
vibracores acquired in this study. Radar sub-facies adjacent to vibracores are
indicated in the boxes paralleling the islands 84
40. Photograph shows typical Shelly Sand (S(sheiiy) ) lithofacies. This lithofacies
consists of 1-55% shell material 85
41. Photograph shows typical Gravelly Shelly Sand (gS(sheiiy) ) lithofacies. This sub-
facies contains 1-80% shell material 88
42. Photograph shows typical Gravelly Sand (gS) lithofacies. This sub-facies
contains less than 1% shell material 89
43. Photograph shows typical Muddy Sand (mS) lithofacies 91
44. Photograph shows typical Massively Bedded Sand (S (mas) ) lithofacies 93
45. Photograph shows typical Heavy Mineral Laminated Sand (S (lam) ) lithofacies...95
46. Photograph shows typical Rooted Sand (S (nd) ) lithofacies 98
47. Photograph shows typical Shelly Sandy Gravel (sG(sheiiy) ) lithofacies. This sub-
facies contains 30-90% shell material 100
48. Photograph shows typical Massive Mud (M(mas) ) lithofacies 102
49. Photograph shows typical Sandy Mud (sM) lithofacies 104
50. Photograph shows typical Peat (P) lithofacies 106
51. Legend explains lithofacies illustrations as they occur in the following
section 108
XV
52. A 2003 DOQQ (USGS) shows the location of the Rodanthe Non-
Migrating/Complex Inlet and surrounding radar facies. The green dot represents
the site of the vibracore acquired within the non-migrating/complex inlet. The
extent of the GPR data shown in Fig. 53 is represented by the yellow line along
NC Highway-12 109
53. GPR data with interpretations (red) shows the Rodanthe Non-migrating/Complex
Inlet. The vibracore location acquired within the non-migrating/complex inlet is
shown. A legend for lithofacies is provided in Figure 51. Two OSL ages are
indicated 110
54. A 1998 DOQQ (USGS) shows the Salvo region. Locations are shown of
vibracores (red) and two GPR transects (yellow) that occur in Figure 55. The
location of the Salvo Complex Inlet and other radar facies in the vicinity are
represented by colored blocks paralleling the Outer Banks 112
55. GPR data are shown with interpretations (red) from two GPR transects in the
Salvo region (Fig. 54). GPR Transect A shows a complex inlet to the north of the
Salvo Complex Inlet. GPR Transect B shows the Salvo Complex Inlet. The
locations of all vibracores (lithofacies legend in Fig. 51) acquired in the region are
shown. Core logs for the nine vibracores taken at the Salvo Day Use area are
presented in figures 57 and 58. Vertical exaggeration = 70x 113
56. Vibracore SalIn-05-VC2 (lithofacies legend in Fig. 51) was obtained within a
relict complex inlet north of the Salvo Day Use area in the town of Salvo (Fig. 54)
and is projected on to the NC Highway-12 GPR data (GPR Transect A in Figure
55). An OSL age is indicated 114
57. Vibracores acquired in the Salvo Day Use area (lithofacies legend in Fig. 51)
were acquired within the Salvo Complex Inlet (Fig. 54) and projected on to the
NC Highway-12 GPR data (GPR Transect B in Figure 55). An OSL age is
indicated 115
58. Vibracores Salvo DUA-05-S5 and Salvo DUA-05-S5B (lithofacies legend in Fig.
51) were acquired within the Salvo Complex Inlet (Fig. 54) and projected on to
the NC Highway-12 GPR data (GPR Transect B in Figure 55). An OSL age is
indicated 116
59. Vibracores SalIn-05-VCl and SalIn-05-VClB (lithofacies legend in Fig. 51) were
obtained from the southern Salvo Day Use area (Fig. 54) and projected on to the
NC Highway-12 GPR data (GPR Transect B in Figure 55). Two OSL ages and
two radiocarbon ages from these cores are indicated 117
XVI
60. A 1998 DOQQ (USGS) shows the Kinnakeet region. Locations of vibracores
(red) and the NC Highway-12 GPR transect (yellow) (Fig. 61) are shown. The
location of the Kinnakeet Complex Inlet and other radar facies in the vicinity are
represented by colored blocks paralleling the Outer Banks 119
61. GPR data with interpretations (red) shows the Kinnakeet Complex Inlet. The
vibracore locations (lithofacies legend in Fig. 51) are shown within the complex
inlet. Vertical exaggeration = 30x 120
62. Vibracores KinnIn-05-S and KinnIn-05-VC2 (lithofacies legend in Fig. 51)
acquired from the northern edge of the Kinnakeet Complex Inlet (Fig. 60)
projected on to an enlarged section ofNC Highway-12 GPR data. Three OSL
ages are indicated. Vertical exaggeration = 30x 121
63. Vibracore KiimIn-05-VCl (lithofacies legend in Fig. 51) acquired from the
southern edge of the Kinnakeet Complex Inlet (Fig. 60) and projected on to an
enlarged section of NC Highway-12 GPR data. Two OSL ages are indicated.
Vertical exaggeration = 30x 122
64. A 1998 DOQQ (USGS) shows the Avon region. Locations of vibracores (red)
and two GPR transects (Fig. 65) are shown. The location of the Avon Complex
Inlet and other radar facies in the vicinity are represented by colored blocks
paralleling the Outer Banks 123
65. GPR data shown with interpretations (red) from two GPR transects in the Avon
region (Fig. 67). GPR Transect A shows the northern Avon Complex Inlet. GPR
Transect B shows the southern Avon Complex Inlet. The location of vibracores
(lithofacies legend in Fig. 51) acquired in the region are shown 124
66. Vibracore AvonIn-05-VC3 (lithofacies legend in Fig. 51) was obtained at the
northern edge of the Avon Complex Inlet (Fig. 64) and is projected on to an
enlarged section of NC Highway-12 GPR data. Two OSL ages are indicated ..125
67. Vibracores AvonIn-05-VCl and Avonln-05-VC2 (lithofacies legend in Fig. 51)
were obtained at the southern edge of the Avon Complex Inlet (Fig. 64) and are
projected on to an enlarged section of the NC Highway-12 GPR data. An OSL
age is indicated 127
68. A 1998 DOQQ (USGS) shows northeastern Ocracoke Island. Locations of
vibracores (red) are shown. Radar facies are represented by colored blocks
paralleling the Outer Banks. Locations of detailed GPR and vibracore
illustrations in Figures 69 to 73 are represented by green squares on the
island 128
XVll
69. Vibracore OCR-05-S108-VC1 (lithofacies legend in Fig. 51) was obtained from
the northern Pony Pasture area on northeastern Ocracoke Island (Fig. 68) and is
projected on to NC Highway-12 GPR data. An OSL age is indicated 129
70. Vibracore OCR-05-S109-VC1 (lithofacies legend in Fig. 51) was obtained from
the southern Pony Pasture area on northeastern Ocracoke Island (Fig. 68) and is
projected on to NC Highway-12 GPR data. An OSL age is indicated 130
71. Vibracore OCR-05-S111-VCl (lithofacies legend in Fig. 51) was obtained from
the central Pony Pasture area on northeastern Ocracoke Island (Fig. 68) and is
projected on NC Highway-12 GPR data 131
72. Vibracore OCR-05-S110-VCl (lithofacies legend in Fig. 51) was obtained from
northeastern Ocracoke Island (Fig. 68) and is projected on to NC Highway-12
GPR data. An OSL age is indicated 132
73. Vibracore OCR-05-S112-VCl (lithofacies legend in Fig. 51) was obtained from
northeastern Ocracoke Island (Fig. 68) and is projected on NC Highway-12 GPR
data 133
74. Dendrogram results derived from cluster analysis (Ward’s linkage, Euclidean
distances) of foraminiferal data 135
75. Dendrogram results derived from cluster analysis (Ward’s linkage, Euclidean
distances) of grain size data. Supplementary biofacies and lithofacies data are
provided in columns adjacent to the dendrogram. The grain size cluster analysis
was performed only on samples included in the foraminifera cluster analysis in an
attempt to correlate between the two and to aid in paleoenvironmental
interpretations 138
76. Oblique aerial photo (Google Earth) showing Oregon Inlet and its flood and ebb
tide deltas. The ebb tide inlet throat charmel, flood tide delta, and finger charmels
are shown in green, red, blue, and yellow, respectively. Oregon Inlet is a modem
analog for relict migrating complex inlet 153
77. Illustration of typical barrier transgression in the area of an inlet. Panel A shows
morphological features associated with an active inlet. In Panel B the inlet has
closed but relict morphological features exist in the shoreface and estuary. The
relict ebb tide delta and throat channel have been destroyed by wave action in the
shoreface of a transgressing barrier island in Panel C. Panel D shows a barrier
that has experienced significant transgression since inlet closure, migrating onto
the flood tide delta 155
XVlll
78. Georeferenced shoreline from the 1866 U.S. Coast Topographical Sheet No. 792
(D. Ames, personal communication, 2006) projected on to the 1998 DOQQ
(USGS) of Ocracoke Island. The solid pink line represents the location of the
shoreline in 1866 and the dashed pink line indicates shoals present in 1866.
Northeast Ocracoke Island has experienced ~1 km of transgression and central
Ocracoke and Ocracoke Village have experienced relatively little transgression
from 1866 to 1998 156
79. Map of the Outer Banks by Comberford made in 1657 A.D. (Williams and
Johnson, 1996). West is to the top of the map. A continuous barrier chain with
minimal inlets is illustrated directly north and south of the unnamed cape. The
Outer Banks is drawn with minimal detail. Roanoke Island is depicted as a nearly
circular island that is open to the ocean 161
80. Map of the Outer Banks by Lawson made in 1709 A.D. (Hawks, 1858). The
region of the Outer Banks north of Cape Hatteras to the Roanoke Island region
shows multiple inlets creating a semi-continuous to discontinuous barrier
chain 162
81. Comparison of maps illustrating the Outer Banks. The 1733 map by Mosely and
1764 map by Beilin (Williams and Johnson, 1996) are not as detailed as the
Price-Strother map of 1808 (Williams and Johnson, 1996). Maps of the Outer
Banks have been drawn with more detail and accuracy since the late 1S'**
century 163
82. Map from 1590 A.D. drawn by John White (Williams and Johnson, 1996)
showing the Outer Banks. This map was made five years after the establishment
of the English colony on Roanoke Island. The relative locations of Pamlico
Sound, Ocracoke Inlet, Cape Hatteras, Roanoke Island, and Albemarle Sound are
accurately drawn, but the spatial distribution of inlets on the map does not agree
with GPR data and OSL age estimates from the present study. An unnamed inlet
is illustrated at the location of Cape Hatteras and an unnamed cape is shown at the
location of Wimble Shoals 165
83. A 1998 DOQQ (USGS) shows the progradation of the northern spit platform
associated with Oregon Inlet through time. Shorelines traced from geo-referenced
topographic survey charts and are projected onto the 1998 DOQQ to show the
complex evolution of this spit platform. The location of vibracores OreIn-06-
VCl and OreIn-06-VC2 are represented by the black star 169
XIX
84. Core logs show the stratigraphy and the depositional interpretation at the location
of vibracores OreIn-06-VCl and OreIn-06-VC2 (Fig. 83). Figure 83 illustrates
the locations of historic shorelines at the site of the Oregon Inlet vibracores. The
location of the Oregon Inlet throat channel has changed position continuously
through time since 1849 A.D. resulting in the deposition of the sequences
illustrated above 170
85. A 2003 DOQQ (USGS) shows the Pea Island: S-Curves region following
Hurricane Isabel. The site of vibracore ChicIn-05-Sl is shown (red dot). The
artificial barrier dune ridge was flattened allowing extensive overwash over NC
Highway-12 and onto the back-barrier. The northern Pea Island: S-Curves region
is a future potential inlet site 172
86. This figure illustrates the Radar-Litho-Bio-Facies (RLBF) lithofacies (LF),
lithofacies illustration (legend in Fig. 54), GPR data adjacent to vibracore and
paleoenvironmental interpretations (PI) for vibracore ChicIn-05-Sl. Pis were
made solely on supplemental data 173
87. A 2003 DOQQ shows the town of Rodanthe following Hurricane Isabel. The
location of vibracore RodIn-05-VCl (green dot) is shown. The storm surge
produced extensive overwash and flooding of tidal creeks. Approximately 0.6 m
of sediment was deposited during this event at the site of RodIn-05-VCl from the
overwash event 176
88. This figure illustrates the Radar-Litho-Bio-Facies (RLBF), lithofacies (LF),
lithofacies illustration (lithofacies legend in Fig. 51), GPR data adjacent to
vibracore, paleoenvironmental interpretations (PI), and age analyses for vibracore
RodIn-05-VCl are shown. Two OSL ages are shown 177
89. This figure illustrates the Radar-Litho-Bio-Facies (RLBF), lithofacies (LF)
(lithofacies legend in Fig. 51), GPR data adjacent to vibracore,
paleoenvironmental interpretations (PI), and age analyses for vibracores SalIn-05-
VCl and SalIn-05-VClB. Pis in black were not assigned an RLBF value and
were made solely on supplemental data. Pis in red were assigned a RLBF value
based on GPR, lithologic, and foraminiferal characteristics. Two OSL ages are
shown in black and two radiocarbon ages are shown in blue 181
90. Shallow bathymetric data are presented in blue for Pamlico Sound and Atlantic
Ocean areas adjacent to the Salvo region. Wimble Shoals are evident in the
nearshore environment and likely have influenced the barrier evolution of this
region by refracting waves and redistributing energy upon the shoreface. Depths
are in meters 184
XX
91. This figure illustrates the Radar-Litho-Bio-Facies (RLBF), lithofacies (LF)
(lithofacies legend in Fig. 51), GPR data adjacent to vibracore,
paleoenvironmental interpretations (PI), and age analyses for vibracores Kinnin-
05-VCl and KinnIn-05-VC2 are shown. Pis in black were not assigned an RLBF
value and were made solely on supplemental data. Pis in red were assigned an
RLBF value based on lithologic, foraminiferal, GPR data. Four OSL ages are
shown 186
92. This figure illustrates Radar-Litho-Bio-Facies (RLBF), lithofacies (LF)
(lithofacies legend in Fig. 51), GPR data adjacent to vibracore,
paleoenvironmental interpretations (PI), and age analyses for vibracore Kinnin-
05-Sl. Pis in black were not assigned an RLBF value and were made solely on
supplemental data. Pis in red were assigned RLBF values based on lithologic,
foraminiferal, and GPR data. An OSL age is shown 188
93. Color contour image based upon LIDAR survey data (www.NCfioodmaps.com')
and displays the linear barrier dune ridges (in red and gray colors), NC Highway-
12 (in blue color), and the recurved inlet spits (in yellow and green colors).
Recurved spits, coinciding with the northern edge of an inlet, are apparent as
ridges and swales on the modern surface south and west of vibracore KinnIn-05-
VCl (black dot) and the Kinnakeet Complex Inlet. Radar facies in the vicinity
are represented by colored blocks paralleling the Outer Banks 189
94. Modem bathymetric data (http://www.ngdc.noaa.gov/mgg/coastal/coastal.htmn
are illustrated for Pamlico Sound and Atlantic Ocean adjacent to the Kinnakeet
and Avon barrier island regions (shaded black). Kinnakeet Shoals are evident in
the nearshore ocean environment and numerous channels (in yellow colors) occur
on Harteras Flats (in red colors). These back-barrier channel features are
interpreted to be the result of extensive inlet activity in the regions 191
95. This figure illustrates Radar-Litho-Bio-Facies (RLBF), lithofacies (LF),
(lithofacies legend in Fig. 51), GPR data adjacent to vibracore,
paleoenvironmental interpretations (PI), and age analyses for vibracores Avonin-
05-’VC2 and Avonln-05-’VC3. Pis in black were not assigned an RLBF value and
were made solely on supplemental data. Three OSL ages are shown in black.. 193
96. Illustration explains Fisher’s 1967 hypothesis for the evolution of the Harteras and
Buxton beach ridges. The ridges prograded south from Buxton Woods and were
later breached (likely during a large storm), creating “hurricane sluiceways” that
exist today as shore-perpendicular estuarine shoals to the west of the modem
ridge in the Isabel Inlet region (from Fisher, 1967) 195
XXI
97. Color contour image based upon LIDAR survey data (www.NCfloodmaps.com')
and displays the geomorphic features of Ocracoke Island. Recurved spits
coincide with the southern edge of an inlet and are apparent as ridges and swales
on the modem surface at the southern Pony Pasture area. A possible dune ridge
on the northern edge of the Pony Pasture area is apparent as a shore-perpendicular
ridge. Molar tooth morphologies characteristic of central Ocracoke are indicated.
Locations of vibracores in the Pony Pasture area are shown (black dots) 198
98. Aerial photographs of Dauphin Island, Alabama (USGS photos). The top photo
was taken on September 17, 2004 immediately after Hurricane Ivan. The bottom
photo was taken on August 31, 2005, two days after Hurricane Katrina. Note the
oil platform that washed ashore in the lower left comer. The yellow arrows are
reference points for before and after comparison. These storms formed
morphologies similar to those of central Ocracoke Island and Portsmouth Island
(Rosenberger, 2006) 199
99. This figure illustrates the Radar-Litho-Bio-Facies (RLBF), lithofacies (LF)
(lithofacies legend in Fig. 51), GPR data adjacent to vibracore,
paleoenvironmental interpretations (PI), and age analyses for vibracores OCR-05-
SI 10 and OCR-05-S112. Pis in black were not assigned an RLBF value and were
made solely on supplemental data. An OSL age is shown 202
100. This figure illustrates Radar-Litho-Bio-Facies (RLBF), lithofacies (LF)
(lithofacies legend in Fig. 51), GPR data adjacent to vibracore,
paleoenvironmental interpretations (PI), and age analyses for vibracores OCR-05-
SI08 and OCR-05-S109. Pis in black were not assigned an RLBF value and were
made solely on supplemental data. Two OSL ages are shown 204
101. Illustration explaining the differences between continuous, semi-continuous,
and discontinuous barrier chains. The regions shaded black represent subaerial
barrier islands and the gray arrows indicate marine circulation through breaches in
the barrier chain. The Outer Banks barrier chain has transitioned from continuous
to semi-continuous to discontinuous in response to climate driven fluctuations in
sea-level and storm frequency and/or intensity. The scenarios illustrated are
arbitrary examples and do not represent the nature of the Outer Banks barrier
chain 207
102. Figure summarizing the geologic evolution of the Outer Banks north and south
of Cape Hatteras for the last 4000 years. Summary based on data from this study.
Smith (2004), Ricardo (2005), Culver et al. (2006, in prep.). Grand Pre (2006),
Rosenberger (2006), and Twamley (2006) 208
XXll
103. Figure summarizes age estimates from several studies on the Outer Banks from
Oregon Inlet to Ocracoke Inlet. An increase in inlet activity possibly related to
increased nor’easter activity north of Cape Harteras was experienced during the
Little Ice Age from -550-275 yrs. B.P. The English settlers arrived during this
period of increased inlet activity. Most inlets were active prior to the construction
of the first detailed maps of the area -1750-1800 A.D 213
INTRODUCTION
Purpose of Study
The northeastern North Carolina (NE-NC) coastal system is a dynamic system
which has experienced large-scale changes in estuarine and barrier island environments
throughout the Holocene. This system includes the Outer Banks, a chain of elongate
barrier islands extending over 300 kilometers from the Virginia border to Cape Lookout,
North Carolina (Fig. 1).
The North Carolina Coastal Geology Cooperative (NCCGC), a collaborative
research program involving East Carolina University, North Carolina Geological Survey,
United States Geological Survey, Virginia Institute of Marine Science, and University of
Delaware was formed in 2000 to investigate the Quaternary geologic framework and
dynamics of the NE-NC coastal system. The present project is part of the NCCGC and
aims to decipher the late-Holocene geologic history of the Outer Banks from Oregon
Inlet to Ocracoke Inlet (Fig. 1). The goal is to determine the location, character, and
temporal existence of previous inlets and define the underlying and adjacent facies.
Inlets provide sediment to the back-barrier of the islands and, therefore, are vital
processes in sustaining a barrier island system through time (Godfrey and Godfrey, 1976;
Moslow and Heron, 1978). The spatial and temporal existence of inlets is directly related
to local and regional climatic and hydraulic conditions (including storm activity),
2
76°45’0'’W 76°30'0"W 76°15'0"W 76‘’0'0"W 75°45'0"W 75'30'0''W
?ii— -
-36°30’0''N
Atlantic
Ocean
36° 1 -36°15'0''N
Kitty
Hawk
?36‘’0'0”N
Oregon
35° ^NLET •35M5'0”N
PEA^
ISLAND
S’CURVES ??
RODANTHEi
SALVO -35°30'0'’N
KINNAKEET
{¡AVON
Pamlico HATTERAS
^ Village
Sound \ -35°15'0"NCare
Hatteras
PORTSMOUTH
Hatteras
Inlet -35°0'0"N
ZRACOKB
Inlet
•34‘’45’0"N
Atlantic
Ocean
20 m
?34°30'0"N
Elevation œ.TB.S 15 22.5 30 37.5
¡above MSL
0 m
y - - - - - - - I., Ml .Tj-w- - - - - r - -
76°30'0"W
Atlantic Ocean 76°15'0"W 76°0'0"W 75°45'0"W 75°30'0"W
Figure 1- Color contour image of eastern North Carolina from LIDAR survey data
(www.NCfloodmaps.comf The map illustrates the regional geographic features
and areas discussed in this study.
3
sediment supply, and the local and regional geologic framework (Riggs et al, 1995).
Historic inlet activity has been well documented along the Outer Banks (Fisher, 1962)
by analysis of géomorphologie landforms, historic maps, and aerial photography to
define the temporal and spatial distribution of inlets with the advent of modem
technologies including geophysical tools such as ground penetrating radar (GPR) and
age-dating tools such as optically stimulated luminescence (OSL) now allows for more
thorough investigations of inlet activity that extend beyond the previous studies.
GPR surveys by NCCGC researchers (Mallinson et al, unpub. data; Thieler et al,
in review) identified multiple Holocene inlet channels between Oregon and Ocracoke
Inlets (Fig. 1) using shore-parallel GPR transects along North Carolina HW-12 on the
Outer Banks. These data reveal a complex history of inlet activity including known
historic inlets and previously undocumented inlets with a variety of geometries, cut and
fill patterns, and spatial distributions. However, the three-dimensional (3-D) GPR
framework, sediment fill characteristics, and ages of relict inlets were unknown. These
are the focus of the present investigation.
Sager (1996), Sager and Riggs (1998), Rudolph (1999), Riggs et al (2000), and
Riggs and Ames (2003) reconstructed a complex evolutionary history including periods
of barrier island partial collapse during the Holocene creating an open bay environment
in Pamlico Sound. Partial collapses were followed by subsequent barrier island
formation and extensive inlet formation. More recent studies by Smith (2004), Ricardo
(2005), Grand Pre (2006), and Culver et al (2006) have supplied paleoenvironmental and
chronostratigraphic details to the evolutionary history of the Outer Banks.
4
Members of the NCCGC and other research projects have and are currently
producing detailed studies concerning the Holocene evolution of the Outer Banks and
Pamlico Sound using paleoenvironmental interpretations (Mallinson et al. 2001, 2005, in
review; Smith, 2004; Ricardo, 2005; Culver et al, 2006, in prep.; Grand Pre, 2006; Jomp,
2006; Rosenberger, 2006; Twamley, 2006; Foley, in prep.; Hale, in prep.). Several
important questions have arisen from the data of these projects: When were relict inlets
active? What are the earlier facies into which the inlets incised? Can inlet-fill be
distinguished from adjacent facies based on lithology or paleontology?
The present project will provide further insight into the changing coastal
environment along the Outer Banks by focusing on relict inlet ages and barrier collapse
during the Holocene by using a variety of tools including litho- and biostratigraphic
analysis of vibracores, age dating tools such as '"'C and OSL, and geophysical tools,
including GPR surveys. The results of this study will be used in conjunction with
previous, current, and future NCCGC projects in order to refine conceptual models of
barrier island evolution in response to climate and sea-level change during the Holocene.
Objectives
The main purpose of the present study is to define the ages, characteristics, and
regional extent of the most recent barrier island partial collapse and subsequent channel-
fill facies. This is accomplished by completing five specific objectives.
5
1. Radar Facies
Two and three-dimensional GPR data are used to define characteristic
Radar Facies and Radar Sub-facies to aid in understanding the regional
stratigraphic framework.
IVL.CLhithofaciesThe lithostratigraphic characteristics of relict inlet and adjacent facies aredetermined using sedimentological analyses on vibracore sediments. Sedimentsarreocnhoasratcraterized utilizing grain size analysis, description of contacts and biotictraces (e.g. bioturbation, roots), and identification of sedimentary structures andfossil contentitg. rTahese sediment characteristics are used to define the lithofacies.III. BiofaciesDetailed apnhailcysis of foraminifera and macrofossils in vibracore sedimentsare used to define biofacies and construct a biostratigraphic framework.IV. Paleoenvironmental InterpretationsLithofacies, biofacies, and geophysical data are combined to provide theempirical data upon which paleoenvironmental reconstructions of vibracorerecords are based. An actualistic approach is utilized by comparing modernenvironmental distributions of lithofacies and biofacies with the paleo-inlet dataobtained in the present study.Framework and Paleo-environmental Reconstruction
A chronostratigraphy of environmental change including relict inlet
activity and/or barrier island collapse is constructed using age dating techniques
6
(''*C and OSL). This provides a temporal framework of inlet aetivity as well as
information concerning complete or partial barrier island collapse.
Previous Works
Regional Geologic Setting
The geologic framework underlying the NE-NC coastal system controls the
current processes and dynamics (Riggs et al, 1995). The subsurface sediments in this
region are a 1.5 to 2.0 km thick sedimentary wedge of Mesozoic and Cenozoic deposits
that dip gently to the east (Riggs et al, 1992). The Holocene sediments of the NE-NC
coastal system are perched unconformably upon sediments of Pleistocene age (Riggs et
al, 1992). These Pleistocene sediments have filled the Albemarle Embayment, which is
a regional pre-Miocene depositional basin that is constrained by the Cape Lookout high
to the south and the Norfolk Arch to the north (Ward et al, 1991; Riggs et al, 1992;
Foyle and Oertel, 1997; Riggs and Ames, 2003; Mallinson et al, 2005; Culver et al,
2006). Quaternary strata range up to 85 m thick in the northern Albemarle embayment
and thin to the south (Riggs et al, 1992; Mallinson et al, 2005; in review). As many as
18 depositional sequences have been identified in the Albemarle embayment reflecting a
series of marine transgressions and regressions as a result of sea-level fluctuations
throughout the Quaternary (Riggs et al, 1992, 2000; Sager and Riggs, 1998; Parham
2003, in press; Mallinson et al, 2005).
7
As result of sea level being much lower than present during the last glacial
maximum, multiple fluvial drainage systems incised into the Pleistocene sediments of the
NE-NC coastal system. Riggs et al. (1995) identified the major paleofluvial valleys and
their associated interfluve headland features (Fig. 2). Topographic lows created by these
fluvial paleo-drainage systems of the last glacial maximum have subsequently flooded
during Holocene sea-level rise creating the estuarine system to the west of the modem
barrier island system. The barrier islands formed during the last phase of Holocene
valley-fill and are perched upon a broad, low-gradient, last glacial maximum topographic
high, or interstream divide, which separated the paleo-Pamlico Creek drainage basin from
a comparable basin to the east of the modem Outer Banks (Riggs et al, 1995; Riggs and
Ames, 2003; Mallinson et al, 2005; Culver et al, in prep.).
The Holocene valley-fill histories within the Albemarle, Croatan, and Pamlico
Sounds have been researched extensively using methods similar to this study (Sager,
1996; Sager and Riggs, 1998; Rudolph, 1999; Riggs et al, 2000; Mallinson et al, 2005;
Culver et al, in prep.). Geophysical, lithostratigraphic, and biostratigraphic data from
Holocene valley-fill sediments reveal distinct sequences indicative of transitions from
closed-estuarine to open-estuarine conditions throughout the Holocene. These data
reflect fluctuations throughout the Holocene in inlet activity on the barrier system that
determines the partial or complete collapse of the barrier system versus a more
continuous nature of the barrier islands.
Mallinson et al. (2005) determined that the northern Albemarle Embayment was
an open embayment from around 10 ka to 4.5 ka (Mallinson et al, 2005). Sager and
"^Jïi
CAPE HENRY
SUBAERIAL
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Fig. 2 - Map illustrating the location of underlying paleofluvial valleys in North Carolina (Riggs et al, 1995).
9
Riggs (1998) identified three depositional sequences in the Albemarle Sound indicating
transitions from closed to open to closed estuarine deposition throughout the Holocene
with the modem continuous barrier island system existing from approximately 2900 cal.
yr. BP to the present. Four depositional sequences were identified in the Croatan Sound
by Riggs et al. (2000), indicating fluctuations between a partially to severely breached
barrier system throughout the Holocene. The modem configuration of the Croatan Sound
region did not take shape until approximately 130 yrs. BP (Riggs et al, 2000). Culver et
al. (in prep.) used a core in south-central Pamlico Sound to determine periods of open-
marine circulation within the Pamlico Sound from approximately 4100-3500 yrs. BP and
1100-500 yrs. BP. These periods reflect times of absence of southern portions of the
barrier system and the existence of an open-marine Pamlico Bay as opposed to the
modem estuarine, Pamlico Sound.
Oregon, Hatteras, and Ocracoke Inlets (Fig. 1) are the three modem active inlets
within the field area. Mallinson et al. (in review) have demonstrated that the area around
Ocracoke Inlet is underlain by the paleo-Pamlico Creek drainage (Fig. 3). Ocracoke Inlet
has been active and has not migrated very far from its current location through historic
times (1584 A.D. - present) (Fisher, 1962). The presence of a non-migrating and
constantly active Ocracoke Inlet may be attributable to the underlying paleochannel.
Hatteras and Oregon Inlets were opened during the same hurricane on September 8, 1846
and have remained active since (Fisher, 1962). Neither inlet is underlain by a
paleochannel like that of Ocracoke Inlet (Fig. 3). Instead, both are underlain by the
paleo-interstream divide that underlies much of the Outer Banks (Mallinson et al, in
10
76”30'0"W 76°15'0"W 76°0'0"W 75°45’0"W 75°30'0"W
36°15'0"N- -36°15'0"N
Paleo-Roanoke R
36°0'0"N- -36°0'0"N
-35”30'0"N
35“15'0"N ?35°15'0"N
aleo-Neuse R. /Ç>'
? ?35'’0'0"N
Depth to Pieistoœne
Holocene boundary
(m below SL)
Kilometers ?34'’45'0"N
76“30'0"W 76°15'0"W 76°0'0''W 75°45'0"W 75°30'0"W
Fig. 3. Map showing the paleo-topography of the Pleistocene drainage systems
underlying the Outer Banks (Mallinson et al., in review; Thieler et ai, in review).
11
review). Oregon and Halteras Inlets have migrated approximately 3 km to the south and
2.5 km to the southwest, respectively, since their inception. The migrating nature of
these active inlets may be attributable to the absence of underlying paleo-channels.
Historical Inlet Activity
Inlet openings and island overwash are commonly reported in barrier island
studies (Fisher, 1962, 1967; Susman, 1975; Smith, 2004; Culver et al, 2006). Only three
inlets (Oregon, Halteras, and Ocracoke) currently exist within the study area, but many
additional inlets have dissected the island chain during historical (post 1584 A.D.) times
(Table 1) (Fisher, 1962; G. Ballance, personal communication 2006).
Fisher (1962) produced a thorough resource for modem and relict inlets along the
Outer Banks by summarizing géomorphologie features of relict inlets and giving
positions and dates of known historic and undocumented inlets within the field area
(Table 1). Recent studies using modem geophysical techniques (Mallinson et al, unpub.
data; Thieler et al., in review) have demonstrated that the inlets identified in Fisher’s
1962 study represent only a fraction of the total number of inlet charmels underlying the
Outer Banks. However, the inlet channels identified by Fisher (1962) are a vital part of
understanding inlet activity and its relationship to the fragmentation of the barrier system.
Several problems exist with spatial and temporal data taken from historic maps
according to Fisher (1962). Inlet locations were commonly observed and not surveyed
during the making of earlier maps resulting in disproportionate and inaccurate
positioning. In several cases inlets were often shown on maps as still open although they
Latitude Longitude Known Dates
Inlet Name Location Deg. Minutes Deg. Minutes Maximum Minimum
Oregon southern end of Bodie Island 35 47.2 75 31.8 1846 to present
New Inlet, Dare northern Natteras Island
County 1852 35 41.3 75 29 1658 to 1682
1917 35 39.8 75 28.5 1738 to 1922
1942 35 40.2 75 28.5 1932 to 1945
35 38.4 75 28.1 1657 to 1682 ca.1672
Loggerhead northern Natteras Island 1852 to
1843 to 1870
1869
35 37 75 28 1657 to 1682 ca.1672
Chickinacommock northern Natteras Island 1722 to
1682 to 1770
1755
Keneckid Kinnakeet Region, Natteras Island 35 30 75 28.75 ca. 1711
Buxton north of Buxton 35 17.5 75 30.9 1962 to 1963
Natteras Island,
Chacandepeco immediately north 35 16.25 75 31.25
pre-1585 to pre-1585
of Cape Natteras 1672 to 1657
35 13.2 75 39.8 1933
Isabel north of Natteras Village
35 13.2 75 39.8 September 2003
Table 1. Table summarizes historic inlets between Oregon Inlet and Ocracoke Inlet. Data are from Fisher (1962) and G.
Ballance (personal Communication, 2006). Table is modified from Smith (2004). Approximate locations are based on
historical maps and records.
Latitude Longitude Known Dates
Inlet Name Location Deg Minutes Deg Minutes Maximum Minimum
western end of lower Harteras
Harteras 35 11.2 75 45 1846 to
island present
Wells Creek (Ballance) northern Ocracoke Island 35 10.4 75 48.5 1840s to 1850s
Old Harteras (Ballance) northern Ocracoke Island 35 10.1 75 49.1 pre-1^5c8o5ctto 1H-777-7^ 0n pre-1585*to 1755
Shingle Creek northern Ocracoke Island 35 10.1 75 49.0 ???
Old Harteras (Fisher) center of Ocracoke Island 35 9 75 51.5 pre-1H5c8o5ctto 1H-777-70n pre-1585^ t^o 1755
Wells Creek (Fisher) western Ocracoke Island 35 8.2 75 53.5 1840s to 1850s
Old Nye western Ocracoke Island 35 6.6 75 57.5 ???
Ocracoke western end of Ocracoke Island 35 3.6 76 1.4 pre-1585 to present
Table 1 (cont.). Table summarizes historic inlets between Oregon Inlet and Ocracoke Inlet. Data are from Fisher (1962) and
G. Ballance (personal communication, 2006). Table is modified from Smith (2004). Approximate locations are based
on historical maps and records.
14
had actually been closed for years indicating that later maps often simply copied earlier
maps without re-investigating the area. In addition, only the dates of opening or closing
of an inlet were typically recorded on maps forcing Fisher (1962) to assume the period of
activity. Fisher stated that these forced assumptions often created shorter periods of
existence than what the inlet actually experienced.
Maps made from around 1800 A.D. to the present show the spatial and temporal
distribution of inlets along the Outer Banks more accurately than earlier maps (1584 -
~1800 A.D.). Improvements in surveying techniques in the late 18*^ century resulted in
more accurate maps allowing for the determination of inlet activity periods to be accurate
within 3 to 5 years (Fisher, 1962).
Ground Penetrating Radar (GPR)
GPR has proven to be an effective tool in evaluating depositional sequences in
barrier island environments dominated by freshwater (Fitzgerald et al, 1992; Ames et al,
2000; Bristow et al, 2000; Mallinson et al, 2001; Bamhardt et al, 2002; Jol et al, 2002;
Burdette, 2003, 2004, 2005; Havholm et al, 2004; Smith, 2004; Ricardo, 2005; Culver et
al, 2006). GPR involves inducing an electromagnetic signal into the subsurface via a
transmitter in an antenna. The signal reflects off boundaries where there is dielectric
contrast and returns to a receiver in the anterma. The receiver then transmits the signal
back to a control unit where it is processed and displayed (GSSI SIR 2000 manual).
Jol et al. (1996) conducted a comparison of GPR data acquired from sandy barrier
systems from the Atlantic, Gulf, and Pacific coasts. JoFs et al. study demonstrated that
15
the quality of GPR data in barrier island environments is limited by several factors.
Saltwater conducts the electromagnetic GPR signal and so the depth to the saltwater
interface controls the amount of radar penetration. Lithologic homogeneity (sediment
grain size and mineralogy) in the subsurface has the potential to preclude the production
of desirable reflectors. The latter is especially problematic when investigating relict
inlets and adjacent facies since it is not uncommon to see a relict inlet where channel-fill
sands are incised into a sand-dominated lithologic unit. An additional problem
encountered in the present study and not covered in Jol et al. (1996) is peat layers in the
subsurface, which cause attenuation of the GPR signal due to saltwater retention. Jol and
Smith (1995) demonstrated that the GPR signal can propagate through peat horizons at
least 3.7 m thick when there is an adequate amount of freshwater present.
Culver et al. (2006) identified several depositional environments using GPR
techniques on Pea Island, NC. Zones of discontinuous, steeply dipping reflections
(clinoforms), chaotic bedding, and cut and fill structures were interpreted to represent
relict inlets and overwash channels. Steeply dipping clinoform reflections were
representative of inlet or channel migration. Horizontal to nearly horizontal reflections
were interpreted as overwash deposits (Culver et al, 2006). The identification of relict
inlets by Culver et al. (2006) and Smith (2004) support the inferences of relict inlets
based on geomorphological landforms made by Fisher (1962).
Fitzgerald et al. (1992) used GPR to characterize the evolution of a beach-ridge
barrier island at Buzzard’s Bay, Massachusetts. Bristow et al. (2000) investigated the
structure and evolution of coastal foredunes along the Norfolk, UK coast using GPR.
16
Barnhardt et al. (2002) used GPR to analyze the complex stratigraphic framework of
Tavira Island in southern Portugal. In 2005, Bristow et al. determined the rate of dune
migration in Namibia using both GPR and OSL dating.
Burdette (2003, 2004, and 2005) used GPR in conjunction with OSL age
estimates to place relict beach ridges on the Currituck Peninsula, North Carolina in a
chronostratigraphic framework. Paleoshorelines returned ages of 60-25 kya (late
Pleistocene Marine Isotope Stage 3; MIS 3). Based on coral reef terrace studies
(Shackleton and Pisias, 1985; Chappell et al, 1996), MIS 3 is understood to have been a
period when sea level was lower than that of present. This disagrees with the OSL age
estimates of the Currituck paleoshorelines but can be explained by glacio-isostatic uplift
of a forebulge occurring during glaciation (Burdette, 2005; Mallinson et al, in review).
GPR was used in conjunction with radiocarbon and OSL age estimates in a study
by Havholm et al. (2004) to place the evolution of dune systems on the northern Outer
Banks and coastal areas of southeastern Virginia in a chronostratigraphic framework.
Multiple periods of dune activation were discovered during the late Holocene: 740 A.D.
(1232 +/- 65 yrs BP), 1260 A.D. (742 +/- 52 yrs BP), and 1810 A.D. (187 +/- 15 yrs BP).
Havholm et al. (2004) speculated that these periods of dune activity were related to
climate change in the late Holocene.
Mallinson et al. (in review) investigated relict beach ridges in Kitty Hawk Woods
on the northern Outer Banks using GPR and OSL and '“^C age estimates to date a late
Holocene depositional sequence transition from regressive (3-2 kya) to transgressive
17
(between approximately 2 and 1 kya to present). Climate change and relative sea-level
fluctuations during these times were speculated to be the mechanisms for these changes.
Jol et al. (2002) used 2-D and 3-D GPR to produce subsurface images of a coastal
barrier spit in Long Beach, WA. They concluded that 3-D depositional frameworks can
be interpreted in more detail than from widely spaced 2-D profiles. They further stated
that 3-D GPR has the potential to greatly improve our knowledge of the distribution and
geometries of sediment facies in coastal environments.
Sedimentological Characterization
Multiple studies along the Outer Banks have shown that subenvironments such as
inlet-fill sediments, overwash deposits, backbarrier shorelines, relict dune ridges,
intertidal marshes, and maritime forests (Fig. 4) can be identified in the subsurface by
evaluating sedimentological and ecological characteristics (Susman, 1975; Susman and
Heron, 1979; Heron et al, 1984; Smith, 2004; Mallinson et al, 2005; Culver et al,
2006). Some environments are not easily distinguishable or identified due to similar
sedimentological characteristics.
Inlet-fill deposits consist of one or more fining-upward sequences composed of a
basal shelly and gravelly, coarse grained sand overlain by a medium to fine clean sand
with heavy mineral laminations that becomes muddier up-core, sometimes capped with a
muddy marsh deposit (Hayes, 1980; Moslow and Tye, 1985; Culver et al., 2006).
Sequences of inlet deposition represent paleoenvironmental transitions from active inlet
channel to prograding spit platform to salt marsh (Moslow and Tye, 1985). Difficulties
Mean sea level
Mean sea
Grasslands level
Overwash fan
Fig. 4. Illustration shows the surface environments and sub-environments common to barrier islands (Godfrey and
Godfrey, 1976).
19
arise when attempting to distinguish between inlet-fill sediments, tidal delta sediments,
and overwash deposits due to very similar sedimentological characteristics.
It has been estimated by Susman and Heron (1975) that as much as 30% of the late
Holocene sediments beneath Shackleford Banks are inlet related and Heron et al. (1984)
suggested that Core Banks has a similar composition. The present study used additional
parameters that were not available at the time the Susman and Heron and Heron et al.
studies were conducted to make an accurate measurement of the amount of channel-fill
sediments in the late Holocene section of the Outer Banks between Oregon Inlet and
Ocracoke Inlet.
Several studies (Hennessy and Zarillo, 1987; Collins et al, 1999; Donnelly et al,
2001a & b; Smith, 2004; Culver et al, 2006) have examined and defined overwash
deposits in barrier island environments as poorly sorted, shelly and gravelly, medium
sand often with heavy mineral laminations, commonly overlain and underlain by finer
grained marsh deposits. Sorting and grain size varies according to the proximity or distal
location of overwash deposition. Mud content was diagnostic in distinguishing overwash
(no mud) and fiood-tidal delta (slightly muddy) facies by Hennessy and Zarillo (1987).
Overwash deposits form when a storm event breaches primary and/or secondary dune
ridges, resulting in channelized flow over the interior of the island that deposits sediment
on the backside of the island in the shape of a fan delta. Overwash also occurs when a
storm surge overtops the primary and/or secondary dune ridge and inundates the back-
barrier environment with a continuous sheet of water and sediment.
20
During the closing stages of an inlet, a topographically low (< Im) and non-
vegetated sand flat is exposed during the transition from a subaqueous to subaerial
environment making this area extremely prone to extensive overwash until vegetation
and subsequent vertical aggradation can be established, which can take several years.
Therefore, when studying relict inlets it should not be surprising to encounter channel-fill
sands overlain by overwash sands in the subsurface stratigraphy. Differentiating between
these two kinds of sedimentary units becomes very difficult in the case of relict inlets.
Geophysical geometries, therefore, are important in distinguishing between overwash and
inlet-fill.
Smith (2004) used lithology, foraminifera, GPR, radiochronology, and geospatial
data sets to compare and contrast an inlet dominated area (Pea Island) to an area with few
historic inlets (Avon-Buxton area). The study identified fining-upward sedimentary
sequences in the shallow (<7 m) stratigraphic framework consisting of overwash and
inlet-fill facies, overlain by back-barrier shoal and intertidal marsh units deposited over
the last 1000 years. Three fining-upward sequences were discovered in the Pea Island
area and two fining-upward sequences were found in the Avon-Buxton area. The three
Pea Island sequences were deposited during the Early Medieval Warm Period (450-1000
A.D.), the Late Little Ice Age (1700-1850 A.D.), and the transition from the Late Little
Ice Age to the modem warming period (~1850 A.D.) The two sequences of the Avon
Buxton area were deposited during the Late Little Ice Age (1700-1850 A.D.) and the
1962 Ash Wednesday Storm.
21
Grain size analysis (mean grain size, skewness, and sorting) has been used to
differentiate between subaqueous and subaerial coastal depositional environments
(Friedman, 1961; Lario et al., 200; Andrade et al, 2004; Simms et al, 2006). Friedman
(1961) used grain size parameters to characterize dune, beach, and river sediments
throughout North America. The measured skewness and mean grain size of dune
(positively skewed, >1.49 «F) and beach (negatively skewed, <1.49 O) sands were
determined to be diagnostic characteristics for each environment.
Lario et al. (2002) and Andrade et al. (2004) used similar parameters as Friedman
(1961) to distinguish overwash/flood delta deposits from lagoonal deposits in cores from
back-barrier and estuarine environments from barrier systems in Spain, England, and
Portugal. Bivariate grain size plots of mean grain size against sorting showed flood
delta/overwash deposits were typically well sorted and had <1.60 O mean grain size,
whereas lagoonal deposits were typically moderately to poorly sorted and had >1.60 O
mean grain size.
Mustang Island, a barrier island in Texas, was investigated by Simms et al. (2006)
by using grain size parameters in order to distinguish between multiple barrier island
facies. This study was able to distinguish dune/beach and barrier-flat (back-barrier)
facies using grain size parameters. These facies could not be distinguished using mean
grain size or sorting, but the skewness of the dune/beach facies was less (-0.05-0.175)
than the barrier-flat facies (> 0.2).
22
Foraminiferal Characterization
Down-core assessment of environmental change can be accomplished using
benthic foraminiferal assemblages to help differentiate lithologically similar sedimentary
facies. Many studies (e.g., Phleger, 1960; Grossman and Benson, 1967; Woo, 1992;
Collins, 1996; Woo et al, 1997; Culver eta/., 1996, 2005; Woo et al, 1997; Collins et
al, 1999; Hippensteel and Martin, 1999; Sedgwick and Davis, 2003; Scott et al, 2001,
2003; Dormelly et al, 2004; Smith, 2004; Ricardo, 2005; Rosenberger, 2006; Twamley et
al, 2006; Hale et al, in prep.) have used foraminiferal assemblages as indicators of
coastal depositional facies and have proven to be a useful tool for interpreting
paleoenvironments and sea-level fluctuations in coastal systems worldwide.
Preservation of foraminiferal assemblages in barrier island facies is often poor
due to reworking of sediments and acidic nature of some back-barrier marsh waters.
Sedgwick and Davis (2003) reported that reworking of sediments efficiently destroys
delicate tests leaving only more robust tests (e.g., Quinqueloculina) in high energy
deposits (i.e., overwash, inlet-fill). Goldstein and Watkins (1999) discovered a decrease
in preservation potential of agglutinated and calcareous taxa below 10 cm in a salt marsh
on St. Catherines Island in Georgia due to increased dissolution of calcite below this
depth.
Elphidium excavatum, Elphidium subarcticum, Elphidium galvestonense,
Elphidium mexicanum, Hanzawaia strattoni, Ammonia parkinsoniana, and Buccella
inusitata comprise a typical offshore foraminiferal assemblage (Schnitker, 1971;
Workman, 1981; Culver et al, 1996, 2006; Collins et al, 1999; Hippentsteel and Martin,
23
1999; Sedgwick and Davis, 2003; Scott et al., 2003; Donnelly et al, 2004; Smith, 2004)
that is commonly found in barrier island overwash deposits. Hippensteel and Martin
(1999) and Collins (1999) investigated back-barrier overwash deposits as indicators of
storm activity along the South Carolina coast by using grain size and foraminiferal data
obtained from vibracores. These studies concluded that overwash fans can best be
identified by offshore foraminiferal taxa that have undergone a significant amount of tidal
reworking. Taxa therefore; are often well sorted and weathered. Culver et al. (2006) used
similar methods to identify overwash deposits on Pea Island on the Outer Banks.
Foraminiferal evidence has been utilized in identifying inlet-fill facies (Culver et
al. 1996; McBride and Robinson, 2003; Robinson and McBride, 2003, 2006). Variations
in foraminferal assemblages were determined by Culver et al. (1996) while examining
back-barrier subenvironments on the Eastern Shore of Virginia. A cluster analysis
distinguished four environments including brackish marsh/channel, lagoonal tidal flats,
lagoonal marsh/washover, and channels/inlets/shoreface. The channels/inlets/shoreface
environment was characterized by the presence of Quinqueloculina seminula (Culver et
al, 1996). Foraminiferal evidence was used to document the history of Currituck Inlet
on the Northern Outer Banks (McBride and Robinson, 2003; Robinson and McBride,
2003, 2006). Freshwater to brackish bay, open inlet (flood tidal delta), closed inlet
(abandoned flood tidal delta/washover fans), and marsh were the four facies identified
from vibracores taken on the abandoned flood tidal delta. Trochammina and rare
Elphidium species were characteristic of the freshwater to brackish bay facies. Species of
Elphidium, Hanzawaia, Planulina, and Quinqueloculina dominated the open inlet facies
24
whereas the closed inlet facies was typically barren of foraminifera. The marsh facies
was dominated by Trochammina inflata, Haplophragmoides wilberti and Miliammina
fusca.
Inlet-fill facies commonly are characterized by foraminiferal assemblages of the
inner shelf. Murray (1969), Schnitker (1971), and Workman (1981) conducted
foraminiferal studies on the continental shelf north and south of Cape Hatteras and found
different foraminiferal assemblages due to the cooler Labrador Current waters to the
north and the warmer Gulf Stream waters to the south of Cape Hatteras. The mid-shelf
assemblages north and south of Hatteras were investigated by Murray (1969). The higher
diversity assemblage to the south included Cibicides pseudoungerianus, Miliolinella
circularis, Quinqueloculina sp., and Trifarina angulosa and the lower diversity
assemblage to the north included Cibicides concentricus, Eggerella advena, Rosalina sp.,
and Stetsonia minuta. Schnitker (1971) studied the entire shelf and was able to
distinguish three environments: nearshore, central shelf, and shelf edge. The nearshore
assemblage was dominated by Elphidium excavatum. Hanzawaia concéntrica, Reophax
atlántica, Peneroplis proteus, Quinqueloculina seminula and Asterigerina carinata were
characteristic of the central shelf assemblage. The shelf edge assemblage included
Lenticulina orbicularis, Cibicides pseudoungerianus and Amphistegina lessonii
(Schnitker, 1971). Workman (1981) studied two sites on the inner shelf north and south
of Cape Hatteras. The assemblages north of Cape Hatteras were dominated by Elphidium
excavatum with Elphidium gunteri. Ammonia tepida and Eggerella advena as subsidiary
species. Several species of Quinqueloculina, with Elphidium excavatum, Elphidium
25
gunteri, Elphidium Umatulum and Ammonia beccarii as subsidiary species were
characteristic of the assemblages to the south of Cape Harteras (Workman, 1981).
Inlet activity and fragmentation of the barrier system allows for increased
estuarine salinity in Pamlico Sound (Abbene, 2004). Grand Pre (2006) conducted a high
resolution foraminiferal study of Holocene sediments recovered in a vibracore from
southern Pamlico Sound. Gulf Stream planktonics and shelf benthic foraminifera
characterized at least two lithostratigraphic units. The earliest period of fully marine
conditions in southern Pamlico Sound was 4100-3500 cal. yrs B.P. and the most recent
period was 1100-500 cal. yrs B.P. (Grand Pre, 2006; Culver et al, in prep.). These
periods generally coincide with the mid-Holocene Hypsithermal and the Medieval Warm
Period climatic events respectively (Culver et al, in prep.)
Culver et al. (2006) described the foraminiferal assemblages for different barrier
island environments of Pea Island, North Carolina. Elphidium excavatum, Elphidium
subarcticum, Hanzawaia strattoni, and Buccella inusitata are calcareous benthic
foraminifera that are often found in coarse sands typical of beach and shallow-offshore
assemblages. The nearshore, back-barrier estuarine sands of Pamlico Sound contain a
low diversity assemblage dominated by Ammobaculities dilatatus (Culver et al, 2006).
The modern peat marshes of the back-barrier environment are characterized by
assemblages of Trochammina inflata, Miliamminafusca, Tiphotrocha comprimata,
Jadammina macrescens, Arenoparrella mexicana, and Haplophragmoides wilberti
(Culver et al, 2006; Culver and Horton, 2005).
26
Other studies have used foraminfera as paleoenvironmental indicators in defining
the late Holocene evolution of the Outer Banks (Smith, 2004; Ricardo, 2005;
Rosenberger, 2006; Twamley et al, 2006; Hale, in prep.) (Fig. 1).
The Salvo-Gull Island area (Fig. 1) was studied using similar methods by Ricardo
(2005). This area has historically experienced more inlet activity than the overwash
dominated Pea Island area to the north. Ricardo (2005) encountered six litho/biofacies in
the shallow subsurface: estuarine shoal sand, estuarine shoal mud, back-barrier salt
marsh, open marine/ inner shelf sand, open marine/ inner shelf muddy sand, and
overwash sand (Ricardo, 2005). The open marine/inner shelf unit was dated and
interpreted to have been deposited in an open embayment from ~3,000 to 1250 cal. yr BP
(Ricardo, 2005). Ricardo (2005) concluded that a semi-enclosed embayment existed in
the Salvo-Gull Island region after 1250 cal. yrs B.P. characterized by active migrating
inlets.
Twamley et al. (2006) and Rosenberger (2006) encountered a similar open
marine/iimer shelf unit in the shallow subsurface further to the south at the Harteras
Village area and Portsmouth Island, respectively (Fig. 1). A basal peat in the Harteras
Village area returned a '“‘C age of -500 cal. yrs. B.P., which correlates well with the
findings of Ricardo (2005) (Twamley, 2006). Rosenberger (2006) dated open
marine/inner shelf sands deposited in the Portsmouth Island region and interpreted the
area to be characterized by a subaqueous bar from 1200-500 yrs. B.P. This open
marine/inner shelf unit was encountered at similar depths (-2-7 m) in the studies of
Ricardo (2005), Twamley et al (2006), and Rosenberger (2006). It appears to be an
27
extensive unit that underlies a majority of the central and southern regions of the Outer
Banks.
METHODOLOGY
Ground Penetrating Radar Data Acquisition and Analysis
GPR data were initially collected along North Carolina Highway-12 (that runs
along the Outer Banks) in the summers of 2001 and 2002. These data were used to
identify and target relict inlet channels for further GPR surveys. Data were obtained using
the Geophysical Survey Systems, Inc. (GSSI) SIR-2000 system with a 200 MHz antenna
in monostatic mode during the summer and fall of 2005 and summer of 2006. The 200
MHz antenna was used in order to acquire shallow (generally between 2 m and locally up
to 7m), high resolution data.
Seven detailed three dimensional (3-D) images of portions of relict inlets within
the field area were produced offering an additional visual aid to understand the
underlying geologic framework, fill patterns within relict charmels, and associated
adjacent barrier facies. GPR data for 3-D images were collected at accessible and open
areas over the designated area of relict inlets. A Polaris two-seater all terrain vehicle
(ATV) dragged the antenna at approximately 2 miles per hour at close intervals (1 m)
over a pre-established grid while the readout on the SIR-2000 system was monitored and
28
notes were collected (Fig. 5). GPR data were collected at 16 bits/sample, 512
samples/scan, and 4 or 5 scans/meter with a recording range of 300 ns. A Trimble
Differential Global Positioning System (GPS) was used to obtain positions of 3-D grids.
All GPR data were downloaded onto a computer for post-processing. The raw GPR data
were compiled into a 3-D file using Radan 6.5. The 3-D file allows for batch processing,
including bandpass filtering and gain adjustment, on each file in a 3-D grid
simultaneously. Once the 3-D file is processed, the 3-D cube is able to be manipulated to
aid in interpretation.
Vibracore Acquisition and Analysis
Twenty-seven vibracores were obtained at or near selected sites of known relict
inlets according to Mallinson (unpublished data) and Fisher (1962, 1967). The outside
edges of relict inlets, areas directly adjacent to relict inlets, and sites of 3-D GPR surveys
were targeted in order to recover both channel-fill and adjacent facies. Vibracoring was
not attempted in the central region of relict channels due to the greater depth of the
channel bottom. Table 2 summarizes the number, location, penetration, and recovery of
vibracores.
Vibracoring involves using a generator to induce a high frequency vibration into
unconsolidated sediment, loosening the sediments so that a 3 inch diameter aluminum
pipe may penetrate. A 4 m high tripod guides and stabilizes the pipe during penetration
29
Figure 5 - Photograph shows the setup for GPR data acquisition. Data were acquired by
towing the GPR antenna at approximately 2 miles per hour with a Polaris two-
seater ATV. The passenger monitored the readout and collected field notes.
30
Date
Collected Vibracore Location Penetration Recovery
Chicln-05-S1 35''24.957'N, 75°29.170'W 4.66 m 3.85 m
Kinnln-05-S1 35°24.957'N, 75'’29.258'W 3.20 m 2.14 m
SalvoDUA-05-S1 35°31.990'N, 75°28.491'W 2.45 m 1.88 m
SalvoDUA-05-S2 35'32.00rN, 75°28.456'W 3.69 m 1.35 m
7/10-15/2005 SalvoDUA-05-S3 35‘'32.038'N, 75-28,455^ 2.64 m 1.35 m
SalvoDUA-05-S3B 35°32.038'N, 75°28.455'W 4.01 m 2.69 m
SalvoDUA-05-S4 35°32.032'N, 75°28.466'W 3.56 m 1.05 m
SalvoDUA-05-S4B 35°32.032'N, 75°28.466'W 4.06 m 1.20 m
SalvoDUA-05-S5 35°31.936'N, 75°28.361'W 3.01 m 1.03 m
SalvoDUA-05-S5B 35°31.936'N, 75°28.36rW 3.34 m 1.72 m
OCR-05-S108-VC1 35°9.476'N, 75°50.792'W 4.73 m 4.15 m
OCR-05-S109-VC1 35‘'8.878'N, 75°52,329'W 5.66 m 5.28 m
10/29-30/2005 OCR-05-S110-VC1 35“10.549'N, 75‘’47.841'W 6.16 m 4.04 m
OCR-05-S111-VC1 35°9.162'N, 75°51.502'W 4.76 m 2.76 m
OCR-05-S112-VC1 35‘’10.639'N, 75°47.617'W 5.80 m 2.87 m
Avonln-05-VC1 35°20.180'N, 75°30.355'W 4.00 m 1.49 m
Avonln-05-VC2 35°20.185'N, 75‘'30.358'W 3.88 m 1.70 m
Avonln-05-VC3 35°21.257'N, 75°30,187'W 2.79 m 1.76 m
Kinnln-05-VC1 35°24.343'N, 75°29.355'W 3.34 m 1.96 m
Kinnln-05-VC2 35°24.802'N, 75°29.278'W 4.73 m 1.92 m
11/18-19/2005 Rodln-05-VC1 35'’35.083'N, 75°28.047'W 6.02 m 3.72 m
Salln-05-VC1 35°31.370’N, 75°28.665'W 6.14 m 4.57 m
Salln-05-VC1B 35''31.370'N, 75°28.665’W 6.40 m 5.04 m
Salln-05-VC2 35‘'33.027'N, 75°28.137'W 3.52 m 2.50 m
Salln-05-VC3 35°32.033'N, 75°28.455'W 6.20 m 3.35 m
Oreln-06-VC1 35'’48.127'N, 75°32.695'W 5.94 m 3.41 m
2/8/2006
Oreln-06-VC2 35°48.130'N, 75°32.700'W 6.02 m 2.32 m
Table 2. Table summarizes vibracore data acquired for this study. Dates collected,
locations, penetrations, and recoveries for each vibracore are shown.
31
and retrieval (Fig. 6). Holes were commonly dug to the water table (usually <1.5 m
below surface) prior to vibracore acquisition. Vibracore penetration started at the depth
of the water table in most cases. This method produced better recoveries than starting
penetration above the water table. Cores up to 5 to 6 meters below the surface were
typically recovered. Field measurements of core penetration, recovered core length, and
length of core lost were recorded. Exact geographic locations of all coring sites were
obtained using differential GPS equipment. Vibracores were used to ground-truth and
define the lithology of reflectors on processed GPR data. Lithofacies and biofacies
analyses were made of the recovered sediments. Age analyses (^“^C and OSL) were
performed on sediment in the vibracores.
Lithofacies Analysis
In the laboratory, each vibracore was split in half using a circular saw. One half
was photographed using a Nikon DlOO digital camera and archived for future
reference. The other half was sampled for lithology, foraminifera, and material for age
analysis. Each vibracore was prepared and logged using the standardized method set
forth by Dr. Kathleen Farrell (NC Geological Survey) and adapted from Folk (1974).
Lithofacies descriptions are based on mega and microscopic analysis including
description of color, grain size at 0.5 G) interval, composition, sorting, sedimentary
structures, and general biota. Once the cores were analyzed mega- and microscopically.
32
Fig. 6. Photograph shows the setup for vibracore acquisition. A 4 m high tripod
stabilized the core pipe during penetration and retrieval.
33
53 samples were taken at selected depths to characterize the major lithologic changes,
depths that correlated well with reflections on GPR data, and adjacent to dated samples.
Detailed sedimentologic analyses were conducted to characterize and distinguish
lithofacies present in vibracores. Samples were dried overnight in an oven at 60 degrees
Celsius and then disaggregated using a mortar and pestle. The sediment was then poured
onto staeked sieves ranging from -2 to 4 O at 0.5 O intervals, placed into a Ro-tap and
agitated for fifteen minutes. Weight percents were calculated using the method described
by Folk (1974) for the fraction of sediment retained on each sieve. Calculated weight
percents were used to derive mean grain size, sorting, and skewness for all samples
(Appendix A).
A Q-mode cluster analysis was performed using Systat 10.2 (Systat Software Inc.)
on only those samples containing >15 specimens of foraminifera using the transformed
weight pereentages for each fraction of sediment retained on each sieve. The grain size
cluster analysis was then compared and correlated to a cluster analysis run on biofacies
data.
Biofacies Analysis
Diagnostic foraminifera and macrofossils were sampled based on lithology, GPR
data, and dated samples. All samples were dried overnight at 60 degrees Celsius and
weighed. Mud and organics were disaggregated using a mixture of small amounts of
sodium metaphosphate [(NaP03)x*Na20] and sodium hydroxide (NaOH) with 300 ml of
34
water. To isolate the sand fraction, the sediment was washed through 63 and TlOgm
sieves, re-dried, and weighed. The sand to mud ratio was calculated from the dry weights
before and after washing. From the sand fraction, foraminifera were separated using
sodium poiytungstate following the procedure outlined by Munsterman and Kerstholt
(1996).
Foraminifera specimens were picked from the floated fraction of separated
material, identified to the species level, and counted (Appendix B). Identifications were
confirmed by comparison with type and figured specimens lodged in the collections of
the Smithsonian Institution, Washington, D.C (Appendix C). All other macrofossils
present in the samples were identified to supplement the foraminiferal data. Using Systat
10.2 (Systat Software Inc.), a Q-mode cluster analysis was performed using the methods
described by Mello and Buzas (1968) in order to recognize foraminiferal assemblages
and to aid in defining biofacies. The contribution of each species to each assemblage was
determined by calculating occurrence (O), constancy (C), and Biofacies fidelity (BF)
(Hazel, 1977). Hazel (1977) defined occurrence as the number of samples in which a
single taxon appears, constancy as the percentage of samples in which a taxon is present
in an individual biofacies, and biofacies fidelity as the faithfulness of a taxon to a
biofacies. The following equation was used to calculate biofacies fidelity:
p
BF = Pi/E Pix 10
i=l
(P = % of occurrences, i.e., constancy)
35
Paleoenvironmental interpretations were made using a combination of
foraminiferal assemblages, macrofossils, lithologic characteristics, and geophysical
geometry.
Age Analyses
Radiocarbon and optically stimulated luminescence (OSL) dating were used to
determine age estimates of sediments and to provide a detailed chronostratigraphic
framework for analysis of paleoenvironments within the field area.
Radiocarbon Dating
Radiocarbon dating is a commonly used tool for dating organic shells and detritus
to define and interpret coastal paleoenvironments. It is assumed that the amount of in
living organic matter is in equilibrium with the atmosphere. Upon death, the amount of
in organic matter steadily decreases via p decay to with a half-life of 5730 years
(Bradley, 1999). With proper calibration to correct for natural variations in '"^C, organic
material can be dated to -40,000 yrs. B.P. (Bradley, 1999). High energy coastal
environments are at risk of contamination from groundwater, organic compounds, and
reworking from storm activity (Bradley, 1999).
’'^C was used to determine the ages of an organic-rich material (peat) and an
articulated Chione cancellata shell. The samples were extracted from the vibracore.
36
wrapped in aluminum foil, placed in a plastic bag, labeled, and stored in a freezer prior to
shipment. Dating was performed by the National Ocean Sciences Accelerator Mass
Spectrometer (NOSAMS) laboratory in Woods Hole, MA. Radiocarbon ages were
calibrated using the CALIB Radiocarbon Calibration Program version 5.0.1 (Stuiver and
Reimer, 1993).
Luminescence Dating
Luminescence dating is a fairly new age-dating technique that has proven to be a
very useful tool not only for dating Quaternary coastal environments, but for Quaternary
research in general. This form of dating is based on quantifying both the amount of
radiation received by a quartz grain during transport prior to burial and the amount of
latent radiation that the grain has experienced over the duration of burial (Aitken, 1998).
A bleaching event refers to the last time the sample was exposed to sunlight long
enough to empty vacancies (imperfections) in the crystal lattice (Aitken, 1998).
Bleaching of quartz sands takes seconds to minutes to occur dependent on the
depositional environment. Quartz sands bleach in approximately 20 seconds subaerially
in full sunlight, 30 seconds in an undisturbed one meter water column, and 3.5 minutes in
a turbid one meter water column (S. Mahan, personal communication, 2006). Rink
(1999) used OSL analyses on modem offshore and onshore quartz sands and confirmed
that quartz sands deposited in marine conditions in offshore and onshore coastal
environments are bleached during transport.
37
Once the sample is buried, radiation emitted from surrounding minerals
containing K, U, Th (with minor additions from cosmic rays and Rb) excites electrons to
higher energy levels (the conductive band), allowing them to become trapped in crystal
lattice vacancies. This builds up a latent signal in the sample (Aitken, 1998), which is
released as luminescence upon stimulation by light. This signal can be measured by
inducing known amounts of additional radiation in a laboratory equal to that received by
the sample subsequent to the most recent bleaching event (Aitken, 1998). This measure
of radiation received during burial is referred to as the paleodose. An accurate age can be
determined by dividing the paleodose (Grays), measured as luminescence, by the dose
rate (Grays/year).
OSL dating was used to date quartz sand from select core sections within the field
area. OSL measures the small amount of light emitted from sediment (quartz) grains
when a beam of light is introduced upon the grains. The event dated by OSL is the age of
last exposure to light (Aitken, 1998; Madsen, et al, 2004).
Twenty OSL samples were obtained from selected channel-fill and adjacent facies
recovered from vibracores. Samples were chosen by three different methods. The first
method targeted high-amplitude dipping GPR reflections, indicative of channel-fill
facies. Samples were extracted by cutting out a 15-20 cm section of core tube at or just
above the depth of a reflection. The age of such samples is taken as indicating the age of
inlet shoaling at that location and depth. The second method was to obtain duplicate
cores within approximately Im of each other. One core was then opened, described, and
correlated to GPR data where available, in order to determine an appropriate sample
38
depth. Based on depths in the first core, the sample section was then cut from the second
core without having to expose the sample to any light source. The third method of OSL
sample extraction was to cut the sample off the bottom 15-20 cm of core tube. This
method was used in areas where there was poor to no GPR signal due to shallow
attenuation by salt water in the subsurface and where no duplicate core was taken.
OSL samples were processed in a dark room, under safelight conditions. Samples
were opened and measurements of sediment moisture content and paleodose rate were
obtained. 2-3 cm of sediment at each end of the sample was discarded and then
approximately 50 g of sediment was removed from the center of the remaining sample
and dry sieved. The >63 pm fraction was saved in a glass vial and labeled, and the <63
pm fraction was placed in a one liter glass beaker and washed with 4 N HCl to dissolve
any carbonate materials. This process was repeated until all carbonate materials were
dissolved. The remaining sediment in the section of core was stored in a plastic bag,
labeled, and kept in safelight conditions as reserve. Each sample was then washed in
35% H2O2 to dissolve any organic materials. A deflocculant (Na pyrophosphate) rinse
was used to break up any aggregates in the sample. Wet sieving then separated the
samples into >250 pm, 250-180 pm, 180-150 pm, 150-125 pm, 125-105 pm, and 105-90
pm fractions. Size fractions were placed in plastic Ziploc bags, labeled, and stored in
safelight conditions. For muddy samples, the <63 pm fraction was transferred to 1 L
plastic graduated cylinders to collect the silt fraction using a settling tube with deionized
water. The finest-grained sample fraction with greater than approximately 15 grams of
sediment was chosen to be used for OSL processing. In this study, these were the 250-
39
180 |im and 180-150 |am fractions. Quartz grains in these fractions were isolated using a
Na polytungstate heavy liquid separation technique. Finally, 50% HF was applied to the
sample to etch the quartz grains.
Fifteen samples were prepared at the USGS Luminescence Dating Laboratory in
Denver, Colorado from January 3-13, 2006 and ftve samples were prepared in a dark
room in the Department of Geology on the East Carolina University campus in
Greenville, NC from March 2-8, 2006. All samples were processed at the USGS
Luminescence Dating Laboratory in Denver, Colorado by Shaimon Mahan from January
to September of 2006. The blue-light OSL method, incorporating the single-aliquot
regeneration- dose technique, was used on quartz grains to determine OSL ages. All
quartz luminescence measurements were made using a Riso TL/OSL reader fitted with
three- 3mm thick Floya U-340 detection filters. Fourteen to 18 aliquots were run per
sample.
40
RESULTS
Geophysical Data
Radar Facies Description
Over 100 km of high-resolution GPR data were collected in the summers of 2001
and 2002 from Oregon Inlet to Ocracoke Inlet along the Outer Banks (Fig. 1). Data were
collected in shore-parallel transects along NC Highway-12. The shore-parallel GPR data
revealed multiple radar facies and sub-facies in the shallow (<6 m) stratigraphic
framework (Figs. 7-11). Figure 8 shows the spatial distribution of radar facies and sub-
facies from Oregon Inlet to Ocracoke Inlet.
Approximately 30 percent of the data are classified as Poor/No Data (Fig. 12).
Attenuation of the electromagnetic GPR signal occurs due to the very shallow (<3 m)
presence of salt water in the subsurface making the interpretation of data difficult to
impossible. Areas lacking interpretable data are characterized by very shallow,
horizontal, and high amplitude reflections underlain with attenuated, indiscernible data.
Historic data of inlet activity (Fisher, 1962) are used as supplemental data in areas where
the GPR signal experienced shallow attenuation. Areas such as Chacandepeco and
Buxton Inlets are classified under the Inlet Radar Facies despite a lack of geophysical
evidence. Oregon, Harteras, and Ocracoke Inlets, all active inlets, constitute
41
RADAR RADAR
FAaES SUB-FAdES
DESCRIPTION GEOMETRY
NON- sVMMi^lklcALimNNa.I NOSED BELOW SEA LEVEL,
MIGRATING/I VERmCAL AGGRADATION SFC
COtVWlON, EPHEIÆRAL INLET
SINGLE COMMONLY CAPPED BY
OVERWftSH
INLET FLAT E.G., WELLSCREEK INLET
NON- SYMMETFMCAL CHANNELI NO SED BELOW SEA LEVEL, SFC-
INLET MGRATINGTlN AND S DIPPING OJNOFORMS,LARGE AND SMALL SCALE OJT
COMPLEX AND FILL SEQUENCES, AREA
INLET REI NO SED AT DIFFEREMTTIMES, E.G., ISABEL INLET
MIGRATING CHANNEL, PROGRADING CLINGFORMS, LARGE-SMALL SCALE
COMPLEX CUT AND FILL SEQUENCES,
E.G., OREGON AND HATTERAS
INLET INLETS, POSSIBLY ACTIVE FOR
OVERWASH CONTINUOUS HORIZONTAL TO 1-5KM-
SU GHTLY SUB- HORIZONTAL SFC- Zone of O-tAcmc Data
FLAT/PEAT HIGH AMPLITUDE FÍEFLEO SEA -2iOVER- PLATFORM TIONS, CHAOTIC DATA NO -5Mlevel"CHANNELS APPARENT I
VNffVSH SHALLOW SYMMETRICALOVERVSiflfiH CHANNEL<S) THAT DO NOT SFC-
INQSE BELOW SEA LEVEL, 7r2-
CHANNEL VERTICAL AGGRADAHON LEVEL
00M*10N, EPHEfÆRAL .5^
POORvNO DATA SHALLOW ATTENUAT!ON,INDISCERNABLE DATA
ACTIVE INLET MODERN OREGON, HATTERAS,AND OCRAOOKE INLETS
Fig. 7. Legend foT Radar Facies and sub-facies encountered during this study. Two
major facies are defined. The Inlet Radar Facies contains three distinct sub-facies
and two unique sub-facies comprise the Overwash Radar Facies. Explanations
are provided for distinctive characteristics for each sub-facies. Areas containing
indiscernible (attenuated) data are classified with gray color and active inlets with
black color.
42
Radar Sub-facies
?'«s ? SNionng-leMiIgnrleatting/
\ RODANTHE! ?CNoomn-pMleigxraIntilnegt /
?Migrati
SALVO Comple
nxg Inlet
?OPevaetrwPalasthfoFrmlat/
? COhvearnwnaesl h
?Poor/No Data
Active Inlet
PAMLICO
SOUND AVON
HATTERAS
CAPE
INLET
HATTERAS
OCRACOKE
INLET ATLANTIC
OCEAN
Fig. 8. NC Highway-12 GPR data summary for the Outer Banks from Oregon Inlet to
Ocracoke Inlet. Data are presented as colored boxes oriented shore-parallel.
Multiple regions can be distinguished as inlet-dominated (blue, red, and orange)
and overwash-dominated (green and yellow). Bathymetric data for Pamlico
Sound are shown (http://www.ngdc.noaa.gov/mgg/coastal/coastal.html).
.Oregon Radar Sub-facies
Inlet Non-Migrating/Single Inlet
?CNoomn-pMleigxraIntilnegt /
?CMoigmraptlienxg Inlet
?OPevaetrwPalasthfoFrmlat/
PAMLICO ^ PEAW ISLAND ?^OCvhearnwnaesl h
SOUND ?Poor/No Data^lActive Inlet
NEW Inlet-1852'
New Inlet-1942
New Inlet-1917 ATLANTIC
Loggerhead Inle' OCEAN
Chickinacommock Inle
RODANnrHE
RODANTTHE I MIGRATING/
\dO^FLEXINLET
SALVO
Kilometers
SALVO COMPLEX INLET
9. Summary of radar facies identified in NC Highway-12 GPR data from Oregon Inlet to the Salvo region. Data are
presented as colored blocks oriented shore-parallel. Approximate locations of historic inlets (Fisher, 1962) are shown
as white boxes. Bathymetric data for Pamlico Sound are provided
(http://www.ngdc.noaa.gov/mgg/coastal/coastal.html). The Rodanthe Non-Migrating/Complex Inlet and the Salvo
Complex Inlet were targeted for closer evaluation using vibracores, age dating, foraminifera, and 3-D GPR surveys.
Kilometers \
0 2 4 8
GULL
ISLAND
ATLANTIC
OCEAN
KINNAKE Radar Sub-facies
REGION Non-Migrating/
PAMLICO K/NNAKEET COMPLEX Single InletINLEI. ?CNoomn-pMleigxraIntilnegt /
SOUND ?CMoigmraptlienxg Inlet
?OPevaetrwPalasthfoFrmlat/
?COhvearnwnaesl h
AVON VON COMPLEX INLET ?Poor/No Data
lActive Inlet
Buxton Inlet.
Chacandepeco Inlet.
CAPE HATTERAS
10. Summary of radar facies identified in NC Highway-12 GPR data from the Salvo region to Cape Hatteras. Data are
presented as colored boxes oriented shore-parallel. Approximate locations of historic inlets (Fisher, 1962) are shown as
white boxes. Bathymetric data for Pamlico Sound are provided (http://www.ngdc.noaa.gov/mgg/coastal/coastal.html).
The Kinnakeet Complex Inlet and the Avon Complex Inlet were targeted for closer evaluation using vibracores, age
dating, foraminifera, and 3-D GPR surveys.
Radar Sub-facies
Non-Migrating/
Single Inlet
Non-Migrating/
Complex Inlet
Migrating
Complex Inlet
Overwash Flat/
Peat Platform
Oven/vash
Channel
Poor/No Data
lActive Inlet
Fig. 11. Summary of radar facies identified in NC Highway-12 GPR data from Cape Hatteras to Ocracoke Inlet. Data are
presented as colored blocks oriented shore-parallel. Approximate locations of historic inlets (Fisher, 1962; G.
Ballance, personal communication, 2006) are indicated by white squares. Conflicting records of locations of historic
inlets exist for Ocracoke Island. Bathymetric data for Pamlico Sound are provided
(http://www.ngdc.noaa.gov/mgg/coastal/coastal.html).
46
Radar Sub-facies
?Hïi SNionng-leMiIgnrlaetting/
?CNoomn-pMleigxraIntilnegt /
?CMoigmraptlienxg Inlet
?OPevaetrwPalasthfoFrmlat/
?COhveanwneasl h
^gjPoor/No Data
^?Active Inlet
Fig. 12. Pie chart illustrates the distribution of radar facies and sub-facies occurrence
from Oregon Inlet to Ocracoke Inlet.
47
approximately eight percent of the study area and are included in the measure of spatial
distribution of inlet activity.
Two distinct radar facies identified from shore-parallel GPR data are Inlet and
Overwash Facies (Fig. 7). Three inlet sub-facies are distinguished within the Inlet Facies
based on channel migration (dipping clinoforms), channel geometry, channel
reincision(s), and spatial extent. The sub-facies include Non-Migrating/Single Inlet,
Non-Migrating/Complex Inlet, and Migrating Complex Inlet (Fig. 7).
The Inlet Facies is the most widely distributed radar facies encountered in the
shore-parallel GPR transects along the Outer Banks. Approximately 40 percent (Fig. 12)
of all acquired data are characterized by N and S dipping clinoforms creating channel-
like geometries interpreted as relict-inlet environments in the underlying stratigraphic
framework.
The Migrating Complex Inlet sub-facies is distinguished from the two other inlet
sub-facies primarily by the occurrence of numerous unidirectional dipping reflections
indicative of channel migration (Fig. 7). The majority (>50%) of clinoforms dip to the S
within the asymmetrical channel of migrating complex inlets, and dip to the N at the very
southern edge of the channel for inlets located from Oregon Inlet to Cape Hatteras (Fig.
7). South of Cape Hatteras to Ocracoke Island the majority of clinoforms dip to the SW
within the asymmetrical chaimel and dip to the NE at the southern edge of the chaimel.
Cut and fill charmels oflen cross-cut dipping clinoforms within this facies, indicating
multiple inlet reoccupations and/or incisions via overwash charmels. The Migrating
Complex Inlet Sub-facies spans greater distances along the barrier island (~l-5 km) than
48
the other two inlet sub-facies (Fig. 13). Active Oregon and Harteras Inlets are modem
analogs to the migrating complex inlet sub-facies because historic maps indicate that each
has migrated ~3-5 km and experienced reincisions since opening in 1846.
The two Non-Migrating Inlet Sub-facies contain unique and distinguishing
characteristics (Fig. 7). The non-migrating/single inlet sub-facies is characterized by a
symmetrical charmel geometry incised below sea level (Fig. 7). A nearly equal amount
of N and S (north of Cape Harteras) and NE and SW (south of Cape Harteras) dipping
clinoforms create the symmetrical geometry of this sub-facies. Nearly horizontal and
parallel reflections stacked on top each other above the base of the charmel are diagnostic
of this sub-facies and indicate vertical aggradation, possibly via overwash in the closing
phase of these relict-inlets (Fig. 7). The Non-Migrating/Single Inlet Sub-facies is
typically the narrowest of the relict-inlet facies (<1 km) (Fig. 7). Small-scale, shallow cut
and fill channels indicative of overwash charmel incision are sometimes present in the
upper portions of this facies (Fig. 7). Large-scale, deeper cut and fill charmels are not
characteristic of the Non-Migrating/Single Inlet Sub-facies suggesting that this sub-facies
forms by single charmel blowouts, likely from individual storm events and existed for no
more than a few years.
The Non-Migrating/Complex Inlet Sub-facies is characterized by the presence of
large-scale cut and fill charmels as compared to the Non-Migrating/Single Inlet Sub-
facies (Fig. 7). These large-scale cut and fill features are created by multiple charmel
incisions occurring within the same region over time. The non-migrating/complex inlet
3.0
2.5
Active
(km) InletsADvisgt.
1.0 Non-
Migrating/ Migrating
Single Complex
Overwash Inlets Non- No/Poor
0.5 Inlets
Channels 1 Overwashi Migrating/
Data
Flat/Peat Complex
T Platform Inlets
0.0
Radar Sub-Facies
Fig. 13. Plot shows the average shore parallel distance of each Radar Facies encountered in GPR data from Oregon
Inlet to Ocracoke Inlet.
50
sub-facies is also characterized by symmetrical channels. Small-scale cut and fill
channels are typical of the Non-Migrating/Complex Inlet Suh-facies (Fig. 7). The Non-
Migrating/Complex Inlet Sub-facies is typically ~0.5-1.5 km wide, which is wider than
the Non-Migrating/Single Inlet Sub-facies and narrower than the Migrating Complex
Inlet Sub-facies (Fig. 13).
Approximately 30% of the GPR data lacked reflections indicating the presence of
relict-inlet channels and were classified within the Overwash Facies. The presence of
Overwash Facies does not discount the presence of underlying, deeper relict inlet
channel-fill. Areas with GPR data interpreted as overwash-dominated are typically areas
where there is poorer (attenuated) data at depth that can not be interpreted as channel-fill.
The extent of the barrier islands characterized hy overwash may be overestimated at the
expense of the extent characterized by inlets. Two distinct overwash sub-facies were
distinguished within the Overwash Radar Facies, the Overwash Flat /Peat Platform Sub-
facies and the Overwash Channel Sub-facies (Fig. 7).
The Overwash Flat/Peat Platform Sub-facies is characterized by continuous
horizontal to slightly sub-horizontal (1-3°) reflections in the shallow (<3 m) subsurface
(Fig. 7). These continuous reflections appear as high, moderate and low amplitudes in
GPR data (Fig. 7). The high amplitude continuous reflections indicate a high lithologic
contrast and are generally interpreted as peat deposits. However, ground-truthing these
data with extensive core sampling would be necessary for accurate environmental
interpretation. Low to moderate amplitude continuous reflections are interpreted as
overwash flats characterized by minor lithologic contrast between strata. Chaotic data
51
(high-amplitude discontinuous reflections) are commonly encountered above continuous
horizontal reflections likely due to the presence of shelly massively bedded deposits. The
Overwash Flat/Peat Platform Sub-facies spans distances from -0.3 to 2 km along the
barrier islands with an average of -0.6 km (Fig. 13) and covers -26 percent of the study
area (Fig. 12).
The Overwash Channel Sub-facies is characterized by the presence of one or
more shallow cut and fill structures that do not incise below sea level (-2 m or less below
surface) (Fig. 7). These overwash charmels are not only characteristically shallow, but
also narrow (0.04- -0.5 km) and symmetrical (non-migrating) (Figs. 7, 13). Data were
attributed to the Overwash Channel Sub-facies when shallow channels cross-cut (incised
into) Overwash Flat/Peat Platform Sub-facies (Fig. 7). Overwash channels were present
in the shallow data of all three inlet sub-facies, and were considered characteristic for
each inlet sub-facies. Areas that contained multiple overw'ash channels were classified
within the overwash channel sub-facies.
3-D GPR Surveys
Nine 3-D GPR surveys were conducted at selected sites within and adjacent to
relict inlet facies to help define and understand the regional stratigraphic framework. 3-D
GPR surveys aid in interpreting the orientation of stratigraphic units and understanding
the processes occurring during inlet closing. The results of these data sets are discussed
in the following section by location from north to south.
52
Pea Island: S-Curves. Two 3-D GPR surveys were conducted in the S-Curves
just north of Rodanthe on July 15,2005 (Fig. 14). The two surveys were parallel to each
other and spaced ~40 m apart. The eastern survey was an 8 x 170 m grid immediately
adjacent to and paralleling NC Highway-12. The western survey was a 10 x 200 m grid
paralleling the eastern grid ~40 m to the west. These two grids are dominated by
overwash facies in the shallow subsurface, whereas a Non-migrating/Complex Inlet was
identified in the 2-D shore-parallel GPR transect ~0.4 km to the south. The approximate
location of historic Chickinacommock Inlet (Fisher, 1962) is -0.6 km to the north (Fig.
14). Figure 14 shows that the stratigraphy underlying the two grids is dominated by the
Overwash Radar Facies. The northern portion of the grids is classified as Overwash
Channel Sub-facies and the southern portion as Overwash Flat/Peat Platform Sub-facies
(Fig. 14). GPR and lithologic core data reveal the presence of a peat platform in this area
at -1 m below the surface. Fig. 15 shows the eastern 3-D survey at S-Curves and reveals
a high amplitude semi-continuous surface at 1.1 m below surface that has been identified
as a peat in vibracore ChicIn-05-Sl taken from within the grid area. The low amplitude
surface is likely an overwash channel/tidal creek incised into the peat platform (Fig. 15).
Figure 16 shows the western 3-D survey and reveals very similar features as described
above for the eastern 3-D survey. The main difference between the two grids is the
location of the low amplitude surface at 1.1 m interpreted as an overwash channel
crossing the area of both surveys. This feature is on the southern portion of the western
grid and the northern portion of the eastern grid (Figs. 15, 16). The two survey areas are
53
Radar Sus-FACtES
Chi cid nacommock m Non-Migrating/Single Inlet
Non-Migrating/
Complex Inlet
Migrating
Western Complex InletOverwash Flat/
3-D GP^ Peat Platform
?OverwashChannel
I Poor/No Data
lActive inlet
Chicln-05-S1
^ Kilometers I
0 0.15 0.3 06 0.9
Fig. 14. A 1998 DOQQ (USGS) shows the Pea Island: S-Curves region directly north of
Rodanthe. The site of the eastern (pink) and western (green) 3-D GPR surveys
and vibracore ChicIn-05-Sl (black dot) are shown. Interpretations of the NC
Highway-12 GPR data are surhmarized in the multi-colored blocks paralleling the
island. 3D data reveal overwash channels/tidal creeks incised into a peat
platform. This area is characterized by overwash channel and overwash flat/peat
platform radar sub-facies. The approximate location of Chickinaccomock Inlet
(Fisher, 1962) is indicated by the white square.
Fig. 15. The eastern 3-D GPR survey acquired in the overwash dominated Pea Island: S-Curves region north of
Rodanthe is 8 m wide, 170 m long, and 5 m deep. The surface at 1.1 m (shown) reveals a peat platform
(continuous high amplitude horizontal reflection) between ca. 110 m and 170 m, and an overwash
channel (low angle dipping reflections) between ca. 0 m and 110 m. The GPR signal becomes
attenuated beneath this horizon.
Fig. 16. The western 3-D GPR survey acquired in the overwash dominated Pea Island: S-Curves region north
of Rodanthe islO m wide, 200 m long, and 4 m deep. The surface at 1.1 m (shown) reveals a peat
platform (continuous high amplitude reflection). The GPR signal becomes attenuated beneath this
horizon
56
oriented shore-parallel (NNW/SSE) and the overwash channel, therefore, must be
oriented NE/SW.
Salvo Complex Inlet. The Salvo Day Use Area, ~1 km south of Salvo, was an
ideal location for an extensive 3-D GPR survey due to its flat, open, and accessible nature
(Fig. 17). On July 12, 2005, a grid of 84 transects, 120 m long and spaced 1 m apart was
acquired in this area (Fig. 18). Figure 18 shows the site is within the region of an
underlying Migrating Complex Inlet, hereafter named the Salvo Complex Inlet. The
Salvo Complex Inlet is bordered by Overwash Radar Facies directly to the north and
Non-migrating/Single Inlet Radar Sub-facies to the south (Fig. 18). The Salvo Complex
Inlet is shown in its entirety in the shore-parallel NC Highway-12 GPR data in Figure 19.
The 3-D survey at the Salvo Day Use area reveals multiple clinoform packages
bounded by erosional surfaces based on the strike and dips of clinoforms at 1.12 m depth;
this geometry indicates variable sediment transport directions from the NE and NW (Fig.
20). At 1.12 m depth, a west/east to northwest/southeast striking and south to southwest
dipping clinoform package cross-cuts a northeast/southwest striking and southeast
dipping clinoform package (Fig. 18). These 3-D data reveal a complex evolutionary
history of the shoaling stages of this region of the Salvo Complex Inlet. This history
could not be discerned in 2-D GPR data.
Kinnakeet Complex Inlet. Two 3-D GPR surveys were acquired within the area
of a migrating complex relict inlet in the Kirmakeet region, hereafter named the
57
Fig. 17. Photograph shows the location of the 3-D GPR survey at the Salvo Day
Use Area. Eighty-four transects, 120 m were acquired in an open, grassy field
ideal for 3-D GPR data acquisition. The Salvo Complex Inlet underlies this area.
58
Radar Sub-facics
I NSionng-lMe iIgnrlaetting/
? CNoomn-pMleigxraIntilnegt /
? CMoigmraptlienxg Inlet
IOPveeantwPalasthfoFrmlat/
?COhvearnwnaesl h
|poof/No Data
Fig. 18. A 1998 DOQQ (USGS) shows the Salvo Day Use Area directly south of the
town of Salvo. The site of the 3-D GPR survey is shown in pink. The GPR
transect shown in Fig. 19 is the yellow line. Interpretations of the NC Highway-12
GPR data are summarized in the multi-colored data paralleling the island.
Salvo Complex Inlet
(DD(emeppthth))
Fig. 19. Processed GPR data (top panel) and interpretations (bottom panel, red) made on GPR data acquired from shore-
parallel transects on NC Highway-12 reveal the geometry of the Salvo Complex Inlet underlying southern Salvo and
the Salvo Day Use area (Fig. 18). Clinoforms are dipping at 3-5°to the south for the majority of the area and then to the
north at the southern extent of the complex inlet. The location of the 3-D GPR survey conducted at the Salvo Day Use
area is shown in gray coloration. Vertical exaggeration = 70x.
Erosional SE
Surfaces' DippingCiinoform Package
1.12 m-;
SE Dipping "^SW Dipping
loform Package Ciinoform Package
4
<^40
50
Distance (m)
Fig. 20. 3-D GPR survey acquired within the Salvo Complex Inlet is 83 m wide, 120 m long, and 6 m deep. The surface at
1.12m (shown) is characterized by at least 2 different sequences of fill based on the strike of ciinoform packages
indicative of varying directions of sediment transport (shown with green arrows) from the NE and NW.
61
Kinnakeet Complex Inlet (Fig. 21). Interpreted GPR data from NC Highway-12 (Fig.22)
illustrates the geometry of the entire Kinnakeet Complex Inlet. The Kinnakeet region is
dominated by the presence of a migrating complex inlet radar sub-facies bounded by the
overwash flat/peat platform facies (Fig. 21).
On July 13, 2005 a 21m x 200 m survey was conducted at a site at the very
northern portion of the Kinnakeet Complex Inlet. This survey was run between the
primary and secondary man-made barrier dune ridges (Figs. 21, 22, 23). NE/SW striking
and SE dipping clinoforms are apparent as high amplitude reflections (Fig. 24) from -1.5
m to -3.5 m depth. These clinoforms are interpreted as relict recurved spits created at the
northern edge of the Kinnakeet Complex Inlet.
A 40 m X 85 m survey was conducted -0.7 km south of the first survey on May 9,
2006 and within the Kinnakeet Complex Inlet (Fig. 21). A flat, sandy area with minimal
vegetation was chosen for the site of the survey (Fig. 23). Prominent high amplitude
reflections revealed slightly NE/SW striking and SE dipping clinoforms from 1.4 m to at
least 3 m depth (Fig. 25). These are indicative of sediment transport from the NW during
the closing stages of the Kinnakeet Complex Inlet.
Avon Complex Inlet. A migrating complex inlet underlies the town of Avon
(Figs. 26, 27) and is hereafter named the Avon Complex Inlet. The 3-D GPR survey was
conducted on May 8, 2006. Interpreted NC Highway-12 GPR data show the entire
geometry of this complex inlet in Figure 28. The Avon Complex Inlet is bordered to the
north by an overwash flat/peat platform sub-facies and to the south by an area with
62
Kinnln-05-S1
Kinnln-05-VC2
3-D GPR^ Radar Sud-tacies
Surveys^ Kinnakeet HNoSr>in-gMleigIrnaletitr>g/
Complex ?Non-Migrating/Complex Inlet
?Migratinginlet Complex Inlet
?Overwash Flat/Peat Platform
Kinntn-05-VC ?
Overwash
Channel
HW-12 GPR / j , '
Transect , ,.f
Fig. 21. A 1998 DOQQ (USGS) shows the Kinnakeet region. The sites of two 3-D GPR
surveys are represented as green boxes on the island. The GPR transect shown in
Fig. 22 occurs as a yellow line. Radar sub-facies based upon the NC Highway-12
GPR data are summarized in the multi-colored data paralleling the island.
Locations of 3 vibracores acquired within the Kinnakeet Complex Inlet are
indicated.
D(emptth)
Fig. 22. Processed GPR data (top panel) and interpretations (bottom panel, red) made on GPR data acquired from shore-
parallel transects on NC Highway-12 reveal the geometry of the Kinnakeet Complex Inlet underlying the
Kinnakeet region (Fig. 21). Clinoforms are dipping at 3-5°to the south and then to the north at the southern
portion of the complex inlet. The locations of two 3-D GPR surveys conducted in the region are shown in gray
coloration. Vertical exaggeration = 30x.
64
Fig. 23. The 3-D GPR surveys within the Kinnakeet Complex Inlet were conducted
between the primary (ridge to the left) and secondary (ridge to the right) man-made
barrier dune ridges. Tracks left by the Polaris ATV in the sand and grasses allowed
for straight transects and accurate 1 m spacing.
Fig. 24. This 3-D GPR survey acquired on the northern edge of the Kinnakeet Complex Inlet is 21 m wide, 200 m long, and 5
m deep (Figs. 21, 22). The surface at 2.12 m (shown) is characterized by NE/SW strike and SE dipping clinoforms
appearing as high amplitude reflections. These features are interpreted as probable recurved spits associated with the
northern edge of the complex inlet.
Fig. 25. This 3-D GPR survey acquired within the Kinnakeet Complex Inlet is 40 m wide, 85 m long, and 5 m deep
(Figs. 21,22). The surface at 1.37 m (shown) is characterized by slightly NE/SW strike and SE dipping
clinoforms appearing as high amplitude reflections. These features indicate sediment transport from the NW
during the closing stages of the complex inlet.
67
Kilometers
0 0.2 0.4 0.8 1.2
HW-12 GPR
Transect
Avon Avon Radar Sub-facies
æ Non-Migrating/
Complex Single Inlet?CNoomn-pMleigxraIntilnegt /
3-D GPR Survey^ ' « ^ > Inlet ?CMoigmraptlienxg Inlet^lOverwasti Flat/
Peal Platform
Overwash
Channel
IPoor/No Data
Fig. 26. A 2003 DOQQ (USGS) shows the town of Avon. The 3-D GPR survey was
conducted in July 2005 and is shown in pink. NC Highway-12 GPR data are
summarized in the multi-colored data paralleling the island. The Avon region is
dominated by the presence of several migrating complex inlets including the
Avon Complex Inlet.
68
Fig. 27. A 2003 DOQQ (USGS) shows the town of Avon. The 3-D GPR survey was
conducted in July 2005 and is shown in pink. Avon is a wide and has not
historically had inlet activity (Fisher, 1962). The use of GPR has revealed that the
region is underlain by a massive relict complex inlet.
,yrT-.^,-rT
Fig. 28. . Processed GPR data (top panel) and interpretations (bottom panel, red) made on GPR data acquired from shore-
parallel transects on NC Highway-12 reveal the geometry of the Avon Complex Inlet underlying Avon (Fig. 26).
Clinoforms are dipping at 3-5°to the south for the majority of the area and then to the north at the southern extent of the
complex inlet. The 3-D GPR survey was conducted in the region shown by gray coloration. Vertical exaggeration =
35x.
70
poor/no data (Fig. 26). A 20 m x 80 m survey was acquired at the site of two bulldozed
housing lots in a development (Fig. 29). The surface at 1.61 m depth reveals a NW/SE
striking clinoform package dipping to the W/SW (Fig. 30) and interpreted as inlet-fill via
sediment transport from the E/NE direction.
Buxton Inlet. The historic Buxton Inlet south of Avon and north of Cape
Harteras (Fig. 31) opened during the Ash Wednesday Nor’easter of March 1962 and was
artificially closed in early 1963 by filling the inlet channel with dilapidated vehicles and
sediment from the adjacent estuarine waters (Riggs and Ames, 2003). A 13 m x 400 m 3-
D survey was conducted at the site of Buxton Inlet on June 22, 2005 directly east of and
parallel to NC Highway-12 (Figs. 31, 32). The surface at 1.06 m shows NE/SW strike
clinoforms dipping to the SE over the northern most —150 m and indiscernible reflections
over the remainder of the surface (Fig. 32). Reworking of artificially introduced sands
via wave and tidal currents results in this artificially filled inlet having similar clinoforms
to those of naturally filled inlets.
Isabel Inlet. A 3-D survey was conducted at the site of historic Isabel Inlet on
July 10, 2005 (Fig. 33 and 34). Isabel Inlet opened by the storm surge of Hurricane
Isabel, a Category 2 storm that impacted the southern Outer Banks in September 2003.
The 9 m X 850 m survey revealed 3 individual channels separated by remnant portions of
an existing peat platform on the 1.98 m surface (Fig. 35). The deepest and most
prominent channel is the northeastemmost one (Fig. 35). Remnant portions of the peat
71
Fig. 29. Photograph of the 3-D GPR survey within the area containing the Avon
Complex Inlet. The survey was conducted on bulldozed lots within a housing
development.
72
Fig. 30. The 3-D GPR survey acquired within the Avon Complex Inlet is 20 m wide, 80
m long, and 7 m deep. The surface at 1.61 m (shown) is characterized by a
NW/SE striking and W/SW dipping clinoform package. These features indicate
sediment transport from the E/NE during the closing stages of the complex inlet.
73
Kilometers
D4 0.8
CJ
Site oi 3-D üPP
Survey at
Buxtofi inlet
Radar Sub-facies
? SNionrg)-lMe igInrlaettir>g/
?CNoomn-pMleigxraIntilnegt /
?CMoigmraptlienxg Inlet
?OPevaetrwPalastifioFrmlat/
?COhvearnwnaesl h
Histone mPoor/No Data
Chacandepeco ^?Active Inletj >
CapéJí VIatteras_. _ . . — A
Fig. 31. A 1998 DOQQ (USGS) shows historic Buxton and Chacandepeco Inlets north
of Cape Hatteras. The site of the 3-D GPR survey conducted in July 2005 is
shown in green. NC Highway-12 GPR data are summarized in the multi-colored
data paralleling the island. Buxton Inlet opened during the Ash Wednesday storm
of 1962 and was artificially closed in early 1963. Chacandepeco Inlet was open
from pre-1585 to -1672 (Fisher, 1962).
74
Fig. 32. The 3-D GPR survey acquired at the site of the 1962 Buxton Inlet is 13 m wide,
400 m long, and 4 m deep (Fig. 31). The surface at 1.06 m (shown) is
characterized by a NE/SW striking and SE dipping clinoform package over the
northern most ~150 m and indiscernible data occurs over the remainder of the
surface. This artificially closed inlet has similar channel-fill sequences as
naturally closed inlets.
Kilometers
¿ÿCape
Hahera^
Radar Sub-facies
‘ 3-D GPR Survey Non-Migrating/
^ Single Inletat site of 2003 Non-Migrating/
Complex Inlet
' Isabel inlet Migrating. Complex Inlet
Overwash Flat/
Peat Platform
Overwash
Channel
^^‘Wattèfas Villa^, Í Poor/No Data?Active Inlet
Fig. 33. A 2003 DOQQ (USGS) shows Hatteras Village and the site of the 2003 Isabel Inlet. The site of the 3-D GPR survey
conducted in July 2005 is shown by the green rectangle on NC Highway-12. NC Highway-12 GPR data are
summarized in the multi-colored data paralleling the island. The site of Isabel Inlet has been opened several times
historically and is classified as a non-migrating/complex inlet.
Radar Sub-facies
B SNionng-leMiIgnrleatting/
ICNoomn-pMleigxraIntilnegt /
Migrating
Complex Inlet
?Overwash Flat/Peat Platform
?OverwashChannel
ü Poor/No Data
lActive Inlet
Fig. 34. A 2003 DOQQ (USGS) shows Halteras Village and the site of the 2003 Isabel Inlet. The site of the 3-D
GPR survey conducted in July 2005 is shown by the green rectangle overlying the inlet. NC Highway-12 GPR data are
summarized in the multi-colored data paralleling the island. The site of Isabel Inlet has been opened several times
historically and is classified as a non-migrating/complex inlet.
Fig. 35. 3-D GPR survey acquired at the site of the 2003 Isabel Inlet is 9 m wide, 850 m long, and 4 m deep.
The surface at 1.98 m (shown) is characterized by three main channels (green shading) eroded through
the remnant peat platform (horizontal reflections). This region has historically been opened several
times historically and is classified as a non-migrating/complex inlet.
78
platform occur as horizontal reflections and separate the channels (Fig. 35). The inlet
was filled within five weeks and GPR data show that, like Buxton Inlet, reworking of
artificially introduced sands produces clinoforms similar to those of naturally filled inlets.
Historic records (S.R. Riggs, personal communication, 2006) and GPR data show the
Isabel Inlet region has been occupied several times (Table 1), and therefore, is classified
as a non-migrating/complex inlet (Figs. 33, 34).
Ocracoke Island. Ocracoke Island historically has been incised by Wells Creek,
Old Hatteras, OldNye, and Shingle Creek Inlets (Fisher, 1962; G. Ballance, personal
communication, 2006) (Table 1). On July 14, 2005, a 3-D GPR survey was condueted in
a flat and sparsely vegetated area behind the artificial primary barrier dune ridge,
immediately north of the approximate location of historic Wells Creek Inlet according to
Fisher (1962) (Figs. 36, 37). The survey location was within an overwash flat/peat
platform radar sub-facies and was bordered directly to the northeast by a non-
migrating/single inlet radar sub-facies and to the southwest by an overwash channel sub-
facies (Figs. 36, 37). A 14 m wide by 215 m long shore-parallel grid area was surveyed.
GPR data revealed chaotic bedding and shallow overwash channels in the shallow (<2 m)
subsurface (Fig. 38), features that are characteristic of the Overwash Radar Facies.
79
Kilometers
Radar Sub-facies
? SNionng-leMiIgnrleatting/
ICNoomn-pMleigxraIntilnegt /
? MCoigmraptlienxg Inlet Shingle Creek Inlet
IOPevaetrwPalasthfoFrmlat/ Old Hatteras Inlet
Ballance
I I Overwash (pers. comm.)Channel
Poor/No Data
Old Hatteræ
Active Inlet Fisher (196;^
DGPR
Fig. 36. A 1998 DOQQ (USGS) shows Ocracoke Island, Hatteras Inlet, and Ocracoke
Inlet. Approximate locations of historic inlets are in white boxes and the 3-D
GPR survey site is shown as the green box on the island. NC Highway-12 GPR
radar sub-facies data are summarized in the multi-colored data paralleling the
island. Contradictory historic inlet approximate locations for Old Hatteras and
Wells Creek Inlets are shown.
Radar Sub-facies
? SNionng-leMiIgnrleatting/
?CNoomn-pMleigxraIntiinegt /
?CMoigmraptlienxg Inlet
? POeveant wPalasthfoFrmlat/
?OChvearnwnaesl h
Poor/No Data
^lActive Inlet
Fig. 37. A 1998 DOQQ shows the approximate location (red) of Wells Creek Inlet according to Fisher (1962). The 3-D
GPR survey site is shown in green. NC Highway-12 GPR radar sub-facies data are summarized in the multi-
colored boxes paralleling the island.
VA
Fig. 38. The 3-D GPR survey acquired immediately to the northeast of the approximate location of Wells Creek Inlet
according to Fisher (1962) on Ocracoke Island is 13 m wide, 215 m long, and 5 m deep. The surface at 0.66 m (shown)
is characterized by chaotic data with a shallow overwash channel around 150-175 m on the NE end of the cube.
Shallow channel geometries incising into horizontal reflections are typical of the overwash facies. Vertical
exaggeration = 45X.
82
Lithofacies Description
Twenty seven vibracores (Table 3) (Fig. 39) were acquired within and adjacent to
areas of known relict inlet channel-fill identified by 2-D GPR transects along Highway
NC-12. Vibracores were examined for texture, composition, sedimentary structures,
color, and biogenic material. Four major lithofacies and nine sub-facies were
distinguished based on sedimentary characteristics (Table 3).
Sand (S) Lithofacies
The Sand Lithofacies was the most extensively encountered lithofacies within and
adjacent to relict-inlets in the field area. This lithofacies varies widely in composition,
color, and texture and was divided into seven sub-facies: Shelly Sand (S(sheiiy)), Shelly
Gravelly Sand (gS(sheiiy)), Gravelly Sand (gS), Muddy Sand (mS), Massively Bedded
Sand (S(mas)), Heavy Mineral Laminated Sand (S(iam)), and Rooted Sand (S(rtd)) (Table 3).
Shelly Sand((Sr^hpihù. The Shelly Sand Sub-facies is a pale yellow (2.5Y-7/3) to
light brownish gray (2.5Y-6/2) to bluish gray (Gley2-5/l), moderately well to moderately
sorted, fine to very coarse, sub-rounded, quartz sand with 1-55% sand to gravel size
shells and angular to rounded shell fragments, black heavy minerals, and sparse (<5%)
organic debris (Fig. 40). This sub-facies is normally graded indicating shiftsin energy
Percent Percent
Major Sub-facies Sediment Color Sedimentary PercentShell
Lithofacies Structures Organic Mud
Material Detritus
Sand (S) Shelly Sand
Pale yellow (2.5Y-7/3)to bluish Massively bedded and normally graded 1-55% <5% None(S(shcllY)) gray (Gley2-5/l)
Shelly Gravelly Pale yellow 2.5Y-7/3) bluish Normally graded, occasionallyto
S3Jld (Gley2-5A) massively bedded, occasional heavy
1-80% None 0-1%
(§S(shelly)) gray mineral laminations
Sand Light yellowish brown (2.5Y) Massively bedded, normally graded,Gravelly to
(gS) (2.5Y-6/1) sandy interbeds common, slightly
0-1% 0-5% 0-1%
gray muddy with burrows
Muddy Sand Light brownish gray (2.5Y-6/2) Massively bedded, often with smallto mud-filled burrows,
dark (2.5Y-3/1) frequently
<5% 0-20% 1-50%
(mS) very gray gravelly, sparse biota traces
Massively Pale
Bedded Sand yellow (2.5Y-7/3) to gray Massively bedded, muddy interbeds 0-1% None 0-1%
(2.5Y-6/1) sometimes present, often burrowed(Simasl)
Heavy Mineral Pale
Laminated Sand yellow (2.5Y-7/3) to very Heavy mineral laminations, sometimes 0-5% 0-5% 0-1%
dark
(S(lain)) gray (2.5Y-3/1)
slightly gravelly, sparse organic debris
Bioturbated with in situ roots and
Dark rhizomes, occasional wood debris,Rooted Sand grayish brown (2.5Y-4/2) to sometimes burrowed, muddy interbeds 0-5% 2-30% 0-1%
(S(rtd)) very dark gray (2.5Y-3/1) frequently present, occasionally slightly
gravelly
Shelly Sandy Pale
Gravel yellow (2.5Y-7/3) to bluish Normally graded and occasionally— 30-90% None 0-1%
(sGfsheitvl) gray (Gley2-5/l)
massively bedded
Massive Mud
Mud (M) Very dark gray (2.5Y-3/1 and 5Y-
Massively bedded, sandy interbeds 90-
sometimes present, organic root traces None 0-40%
(^(mas)) 3/1) 100%and burrows common
Sandy Mud (sM) Very dark gray (5Y-3/1) Massively bedded, sand-filled burrows None None 50-90%
Peat (P) Very dark grayish brown (2.5Y-
Bioturbated and structureless, often
— <5% 40-85% 0-40%
3/2) to black (2.5Y-1/1) sandy and/or slightly gravelly
Table 3. Summary table of lithofacies encountered in this study. Characteristic properties are provided for each lithofacies
Vs \,
',-?3
^«íÍ^Pamlico Sound
Radar Sub-facies
H Non-Migrating/Single Inlet
Non-Migrating/
Complex Inlet
Migrating
Complex Inlet
Overwash Flat/
Peat Platform
?OverwashChannel
Poor/No Data
Active Inlet
Fig. 39. Series of 1998 DOQQ aerial photographs (USGS) show the locations of 27 vibracores acquired in this study. Radar
sub-facies adjacent to vibracores are indicated in the boxes paralleling the islands.
OCR-05-S108-VC1 Shelly Sand (S(3he|,y))
410-425 cm Sub-facies
hell Fragments
TOP
0 3 6 9 12 15 centimeters
Fig. 40. Photograph shows typical Shelly Sand (S(sheiiy) ) lithofacies. This lithofacies consists of 1-55% shell material.
86
regimes during deposition from high to low energy, which commonly occurs in overwash
and charmel-fill deposits (Table 3).
The Shelly Sand Sub-facies occurred in every complex inlet examined
lithologically within the field area and correlated with both the Overwash and Inlet Radar
Facies (Appendix E). This sub-facies also was encountered 1) at -5.25 m below surface
in facies adjacent to the Salvo Complex Inlet, 2) at -4.25 and -5.25 m below surface in
high and low energy depositional environments adjacent to inlets on Ocracoke Island in
vibracore OCR-05-S108 (Appendix E) (Fig. 39), 3) within Overwash Radar Facies in
Rodanthe in vibracore Rod-In-05-VCl (Appendix E) (Fig. 39), and 4) on Ocracoke
Island in vibracores OCR-05-S110, OCR-05-S111, and OCR-05-S112 (Appendix E)
(Fig. 39). This sub-facies also was encountered in vibracores OreIn-06-VCl and Orein-
06-VC2 (Appendix E) (Fig. 39), that contained sediments deposited at the late 1840s
flood tidal delta at the site of the original inlet and the subsequent prograding spit
complex of Oregon Inlet (Fig. 39).
Grain size analyses were performed on four samples from the S(sheiiy) Sub-facies
(Appendix E). These samples had mean grain size (0) values of 1.60 0, 1.89 0, 1.91 0
and 1.97 0 (average mean grain size of 1.84 0) and sorting values of 0.54, 0.76, 0.82,
and 0.96 (moderately well to moderately sorted). All four samples were strongly
negatively skewed (-1.51, -1.98, -2.50, and -3.08) (Appendix A).
Shelly Gravelly Sand (sSf.h^ih,)). The Shelly Gravelly Sand Sub-facies is a pale-
yellow (2.5Y-7/3) to light brownish gray (2.5Y-6/2) to bluish gray (Gley2-5/l), well to
87
very poorly sorted, medium to very coarse, sub-rounded to rounded quartz sand with 1-
80% shell sand to gravel size shells and angular to rounded shell fragments (Fig. 41).
Heavy mineral laminations occur occasionally within this sub-facies. The mud fraction
comprised 0-1% (primarily heavy minerals) and no organics were present in this
subfacies (Table 3).
Every complex inlet in the field area contained the Shelly Gravelly Sand Sub-
facies. The sub-facies correlated with both Inlet and Overwash Radar Facies (Appendix
E). The Shelly Gravelly Sand sub-facies was encountered in relict-inlets.
Grain size analyses were performed on twenty samples from the gS(sheiiy) Sub-
facies. These samples had mean grain size (0) values ranging from -0.12 to 2.13 0 with
an average mean grain size value of 1.25 0. Sorting ranged from 0.42 to 2.84 (well
sorted to very poorly sorted). All 20 samples were skewed negatively ranging from -0.15
to -2.79 (Appendix A).
Gravelly Sand Í2S). The Gravelly Sand Sub-facies is a light yellowish brown
(2.5Y) to gray (2.5Y-6/1), poorly to moderately sorted, coarse to very coarse, sub-
rounded quartz sand with no to extremely sparse (0-1%) shell material, black heavy
minerals, and mud (Fig. 42). Organic debris (grasses) were present in only one area (S-
Curves region) and composed ~5% of the lithologic unit. This sub-facies was commonly
normally graded and interbedded with thin S(iam) sub-facies. Minimal shell composition
is characteristic for this sub-facies and distinguishes it from the gS(sheiiy) Sub-facies (Table
3).
Kinnln-05-VC2 Gravelly Shelly Sand
90-105 nm (9S,.heii»>)Sub-facies
-TOP
0 3 6 9 12 15 centimeters
Fig. 41. Photograph shows typical Gravelly Shelly Sand
material. (gS(sheiiy) ) lithofacies. This sub-facies contains 1-80% shell
Salvo DUA-05-S1 Gravelly Sand (gS)
40-51 cm Sub-facies
Quartz
Gravel
-TOP
o 3 6 9 12 centimeters
Fig. 42. Photograph shows typical Gravelly Sand (gS) lithofacies. This sub-facies contains less than 1% shell material.
90
The gS Sub-facies was encountered only in two sites in the field area. It is most
prevalent in vibracore ChicIn-05-Sl (Appendix E) (Fig. 39) acquired in the Overwash
Radar Facies dominated S-Curves region and only occurs once in vibracore SalvoDUA-
05-S4B (Appendix E) (Fig. 39) acquired at the Salvo Day Use area. No grain-size
analyses were performed on the gS Sub-facies.
Muddy Sand (mS). The Muddy Sand Sub-facies is a light brownish gray (2.5Y-
6/2) to gray (2.5Y-3/1), moderately well sorted to poorly sorted, sub-rounded, lower
medium to lower coarse muddy sand with 1-50% mud, <5 % shells and rounded to sub-
rounded shell fragments, and 0-20% organic detritus (Table 3). This sub-facies is
commonly massively bedded with frequent mud-filled burrows, which is characteristic of
a lower-energy estuarine deposit (Fig. 43).
The mS Sub-facies was not encountered within the channel-fill sediments
examined along the Outer Banks. This sub-facies was identified in facies adjacent to the
Kirmakeet (vibracore KinnIn-05-Sl (Appendix E)(Fig. 39)) and Salvo (vibracores Salín-
05-VCl and SalIn-05-VClB (Appendix E)(Fig. 39)) Complex Inlets and at depth (>3 m
below surface) in vibracores OCR-05-S108 and OCR-05-S109 (Appendix E)(Fig. 39)
from northeastern Ocracoke Island. The mS Sub-facies is common in lower energy
estuarine environments (vibracores KirmIn-05-Sl, SalIn-05-VCl, SalIn-05-VClB, OCR-
05-S108 and OCR-05-S109 (Appendix E) (Fig. 39) where organic matter and shell
material are present (Boggs, 2001)
Salln-05-VC1 Muddy Sand (mS)
287-305 cm Sub-facies
Mud-Filled
Burrows
Chione cancellata TOP
shell
12 15 centimeters
Fig. 43. Photograph shows typical Muddy Sand (mS) lithofacies.
92
Grain size analyses were performed on nine samples from the Muddy Sand Sub-
facies. Mean grain sizes (0) varied from 1.91 to 3.34 0 with an average mean grain size
of 2.62 0. Sorting for these samples ranged from 0.60 to 1.55 (moderately well to poorly
sorted). Skewness values varied widely. Two samples taken from facies adjacent to the
Kinnakeet and Salvo Complex Inlets were negatively skewed (-0.45 and -2.26). The
remaining seven samples (all from Ocracoke Island) were positively skewed (0.01-1.28).
This is explained by the mud content in the samples; the Ocracoke Island samples were
muddier than the Kinnakeet and Salvo Complex Inlet samples. The Muddy Sand sub-
facies was defined as including samples with >1% mud due to the general lack of mud
encountered in vibracore sediments. The presence of mud in relict inlet and adjacent
facies is a diagnostic characteristic that is relevant to making paleoenvironmental
interpretations regardless of the total amount of mud present.
Massively Bedded Sand (Stmn^i). The Massively Bedded Sand Sub-facies is a pale
yellow (2.5Y-7/3) to gray (2.5Y-6/1), well to moderately well sorted, sub-rounded, very
fine to coarse sand composed of 0-1% weathered shells and rounded shell fragments,
very sparse (0-1%) mud, and no organic matter (Table 3). This sub-facies
characteristically lacks sedimentary structures and often contains mud-filled burrows.
Thin muddy interbeds are sometimes present in the Massively Bedded Sand Sub-facies
(Fig. 44).
The S(nias) Sub-facies is encountered in the Overwash and Inlet Radar Facies in
Avon (vibracore AvonIn-05-VCl (Appendix E)(Fig. 39)), Rodanthe (vibracore Rodin-
Salln-05-VC1
TOP
12 15 centimeters
Fig. 44. Photograph shows typical Massively Bedded Sand (S (mas) ) lithofacies.
94
05-VCl (Appendix E)(Fig. 39)), Salvo (vibracores SalIn-05-VCl, SalIn-05-VClB, Salín-
05-VC2, SalIn-05-VC3, SalvoDUA-05-S4, SalvoDUA-05-S4B, SalvoDUA-05-S5
(Appendix E)(Fig. 39)), and Ocracoke (vibracores OCR-05-S110, OCR-05-S111)
(Appendix E) (Fig. 39). The modem overwash facies of Oregon Inlet (vibracore Orein-
06-VC2 (Appendix E) (Fig. 39) contains the Massively Bedded Sand Sub-facies, but the
sub-facies is barren of mud-filled burrows in this region. Mud-filled bunows are
encountered in the facies adjacent to the Salvo Complex Inlet and at ~5 m depth below
surface on northeastern Ocracoke Island. The presence of burrows indicates these sands
existed in slightly lower energy environments than the S(mas) sands lacking mud filled
burrows. Mud-filled burrowed S(nias) sands are interpreted as being deposited in
estuarine environments near the barrier and sometimes adjacent to inlets (Boggs, 2001).
Two samples were analyzed from the Massively Bedded Sand Sub-facies. Mean
grain size 0 values were 1.81 and 2.10 0 with an average of 1.96 0. Sorting values for
the samples were 0.44 and 0.69 (well to moderately well sorted). Both samples were
negatively (-0.53 and -1.66) skewed.
Heavy Mineral Laminated Sand (S(inn,\). The Heavy Mineral Laminated Sand
Sub-facies is a pale yellow (2.5Y-7/3) to very dark gray (2.5Y-3/1), well to moderately
sorted, sub-rounded, fine to medium quartz sand composed of 0% to 5% angular to sub-
rounded shell fragments, organic debris, and 0-1% mud (Table 3). This sub-facies is
characterized by the presence of black heavy mineral laminations consisting mostly of
ilmenite, magnetite, and garnet (Fig. 45). Heavy mineral laminations are characteristic
Heavy Mineral
SalvoDUA-05-S1 Laminated Sand
96-110 cm Sub-facies
Heavy Mineral
Laminations eavy Mineral
Laminations
TOP
12 A® centimeters
Fig. 45. Photograph shows typical Heavy Mineral Laminated Sand (S (lam) ) lithofacies.
96
sedimentary structures of shoreface, overwash, inlet delta, and aeolian dune deposits
(Boggs, 2001).
This sub-facies was encountered in the Inlet and Overwash Radar Facies in the
Avon (vibracores AvonIn-05-VCl, AvonIn-05-VC2 (Appendix E)(Fig. 39), Kirmakeet
(vibracores KinnIn-05-Sl, KinnIn-05-VCl, KinnIn-05-VC2 (Appendix E)(Fig. 39), and
Salvo (vibracores SalIn-05-VClB, SalIn-05-VC2, SalvoDUA-05-Sl, SalvoDUA-05-S3,
SalvoDUA-05-S4, SalvoDUA-05-S4B, SalvoDUA-05-S5, SalvoDUA-05-S5B
(Appendix E)(Fig. 39)) Complex Inlets and on Ocracoke Island (vibracores OCR-05-
SI08, OCR-05-S109, OCR-05-S110, OCR-05-S111 (Appendix E) (Fig. 39) and the S-
Curves region (vibracore ChicIn-05-Sl (Appendix E) (Fig.39). The flood tide delta
created by the original breaching of Oregon Inlet (vibracores OreIn-06-VC 1 and Orein-
06-VC2 (Appendix E) (Fig. 39)) also contains the S(iam) Sub-facies.
Grain size analyses were performed on seven samples from the S(iam) Sub-facies.
Mean grain sizes (0) range from 1.62 to 2.18 0 with an average mean grain size of 1.94
0 (Appendix A). Sorting values range from 0.42 to 1.00 (well to moderately sorted) for
all seven samples (Appendix A). All samples are negatively skewed ranging from -0.15
to -3.41 (Appendix A).
Rooted Sand {Srnrii). The Rooted Sand Sub-facies is a dark grayish brown (2.5Y-
4/2) to very dark gray (2.5Y-3/1), moderately to poorly sorted, sub-angular to sub-
rounded, upper fine to lower coarse quartz sand with <5% rounded to sub-rounded shell
fragments, 2-30% organic material (consisting of in situ roots and rhizomes and
97
occasional wood debris) and 0-1% mud (Table 3). This sub-facies contains in situ
organic material and roots from overlying Peat lithofacies typically in the shallow (<2 m
below surface) subsurface (Fig. 46). The occurrence of this sub-facies in the shallow (<2
m below surface) subsurface can be attributed to vegetated back-barrier deposits adjacent
to salt marshes blanketed by overwash deposits (island roll-over) (Godfrey and Godfrey,
1976).
The S(rtd) Sub-facies occurs in the shallow (<2 m below surface) subsurface in the
S-Curves, Kinnakeet, Ocracoke, Rodanthe, Oregon Inlet, and Salvo regions. This sub-
facies is encountered in vibracores ChicIn-05-Sl, KinnIn-05-VCl, KinnIn-05-VC2,
OCR-05-S108, OCR-05-S109, OCR-05-S110, OCR-05-S111, RodIn-05-VCl, OreIn-06-
VCl, SalIn-05-VCl, SalIn-05-VClB, SalIn-05-VC2, SalvoDUA-05-Sl, SalvoDUA-05-
S3, SalvoDUA-05-S4, SalvoDUA-05-S4B, and SalvoDUA-05-S5 (Appendix E) (Fig.
39).
Grain size analysis was performed on three samples from the Rooted Sand Sub-
facies. Mean grain sizes (0) for the three samples were 1.63, 1.85, and 1.94 0 with an
average mean grain size of 1.81 0 (Appendix A). Sorting values of 0.80, 0.84, and 1.08
classify these samples as moderately to well sorted (Appendix A). All samples are
negatively skewed with values of -2.07, -2.15, and -2.20 (Appendix A).
OCR-05-S110-VC1 Rooted Sand
121-134 cm Sub-facies
12 centimeters
Fig. 46. Photograph shows typical Rooted Sand (S (rtd) ) lithofacies
99
Shelly Sandy Gravel (sG(sheiiy}) Lithofacies
The Shelly Sandy Gravel Lithofacies contains a majority (>50%) of gravel sized
particles (Table 3). This lithofacies is dominated by the presence of shell material and
has minimal textural and compositional variations and does not require further
subdivision (Fig. 47).
Sediments defined as the sG(sheiiy) Lithofacies are pale yellow (2.5Y-7/3) to bluish
gray (Gley2-5/l), very poorly sorted, rounded to sub-rounded, 2 to 5 mm gravel with
medium to coarse sands. This lithofacies contains 30-90% angular to rounded shell
material and can often be defined as a shell hash. Black heavy minerals are commonly
found in shelly sandy gravel units. Sediments are commonly normally graded and
occasionally massively bedded. Coarser deposits such as those of the Shelly Sandy
Gravel Lithofacies are characteristic of high energy environments and are commonly the
basal lithologic units of fining upward sequences of barrier island deposits (Moslow and
Tye, 1985). This lithofacies is found on modem shoreface and overwash deposits and
relict inlet and overwash channel deposits (Moslow and Tye, 1985).
The Shelly Sandy Gravel Lithofacies is encountered in the channel-fill of the
Avon, Kinnakeet, and Salvo Complex Inlets and in or near relict inlet-fill deposits on
Ocracoke Island. All occurrences of this lithofacies correlate with the Inlet Radar Facies.
One sample was analyzed from the Shelly Sandy Gravel Lithofacies. The lithofacies had
the coarsest mean grain size (-0.54 0) and greatest sorting value (3.19) of all analyzed
samples (Appendix A). The sample was skewed negatively (-1.24) like many of the
Salln-05-VC2 Shelly Sandy Gravel (sGj^^gnyj)
TOP
0 3 12 15 centimeters
Fig. 47. Photograph shows typical Shelly Sandy Gravel (sG(sheiiy) ) lithofacies. This sub-facies contains 30-90% shell material.
101
analyzed Sand Lithofacies samples (Appendix A). These deposits are interpreted as
being deposited within or near the throat of inlet channels (Moslow and Tye, 1985).
Mud (M) Lithofacies
The Mud Lithofacies occurred only in facies adjacent to relict inlet channel-fill
and contains greater than 50% mud (Table 3). Occurrences of mud-dominated units were
rare in this study; however, the presence of mud in facies adjacent to relict inlet channel-
fill is extremely important in understanding the evolutionary history of the barrier island
system prior to relict inlet incision.
Massive Mud (M). The Massive Mud Sub-facies is a very dark gray (2.5Y-3/1
and 5Y-5/1), poorly sorted mud composed of 0-40% organic matter and <10% sand
(Table. 3). No shell material or heavy minerals are present in this sub-facies, but
burrows are a common feature. This sub-facies is commonly interbedded with thin (<8
cm) massively bedded coarse sand deposits. The Massive Mud Sub-facies likely was
deposited in a low-energy estuarine environment that existed close enough to the barrier
system to experience sand deposition during high energy storm events (Grand Pre, 2006)
(Fig. 48).
3 6 9 12 centimeters
Fig. 48. Photograph shows typical Massive Mud (M(mas) ) lithofacies.
103
The M Sub-facies was encountered at ~2.5 m below surface in OCR-05-S108 on
NE Ocracoke Island and ~3 and ~4 m depth below surface in sediments from vibracores
SalIn-05-VCl and SalIn-05-VClB that were taken directly adjacent to the southern edge
of the Salvo Complex Inlet (Appendix E) (Fig. 39). Both Massive Mud units in the Salvo
cores are interbedded with lenses of sand and are between massively bedded sands and
burrowed muddy sand units.
The two occurrences of the M Sub-facies in SalIn-05-VCl were analyzed. The
units at ~3 m and ~4 m depth below surface had mean grain sizes of 3.95 0 and 3.93 0,
respectively (Appendix A). Both samples had very similar sorting values (1.84 and 1.83)
and are poorly sorted (Appendix A). These two samples were positively skewed with
values of 1.06 and 1.05 (Appendix A). These deposits were interpreted to be low energy
estuarine environments.
Sandy Mud (sM). The Sandy Mud Sub-facies is a very dark gray (5Y-3/1),
moderately to poorly sorted mud with fine sand and abundant mud-filled burrows (Table
3). No shells are present in this sub-facies and the mud fraction ranges from 50 to 90%
(Fig. 49). These deposits are commonly encountered in estuarine environments such as
flood tide deltas that receive sand deposits from an adjacent active inlet during high
energy events and estuarine muds during times of lower energy (Smith, 2004; Culver et
al, 2006). The presence of bioturbation is characteristic of estuarine flood tide delta
deposits (Smith, 2004; Culver et al., 2006).
Salln-05-VC1 B Sandy Mud (sM)
323-332 cm Sub-facies
Large Sand-
Filled Burrow
TOP
3 12 centimeters
Fig. 49. Photograph shows typical Sandy Mud (sM) lithofacies.
105
This sub-facies only occurs in vibracores SalIn-05-VCl and SalIn-05-VClB
(Appendix E) (Fig. 39) at ~3 m depth below surface in facies adjacent to the Salvo
Complex Inlet. These deposits directly underlie the M Sub-facies in these cores and
share a gradational and burrowed contact with these units. No samples were analyzed
from the sM Sub-facies.
Peat (P) Lithofacies
The Peat Lithofacies is encountered in the shallow subsurface (<2 m below
surface) in regions classified as Overwash Radar Facies (Pea Island: S-Curves region)
and areas adjacent to Inlet Radar Facies (Ocracoke Island, Rodanthe, and Salvo). The
Peat Lithofacies is a very dark grayish brown (2.5Y-3/2) to black (2.5Y-1/1), quartz
sandy, dense, fibric to sapric peat (Table 3). This lithofacies comprises 40-85% organic
material including roots, rhizomes, and plant and wood debris (Fig. 50). Sands are
common in the P Lithofacies and gravels are often present in small (<5%) amounts
(Table 3). The mud fraction ranges from 0% to 40% and shell material constitutes <5%
of the lithofacies when present (Table 3).
The subsurface Peat Lithofacies is currently forming in back-barrier salt marshes
and barrier island interior marshes. The presence of the Peat Lithofacies is significant to
relict-inlet studies because the lithofacies is not characteristic of relict-inlet facies. The P
Lithofacies can loosely be interpreted as a barrier section where inlet activity occurs very
infrequently or not at all since the peat commenced accumulating. The regions in this
Chicln-05-S1 Peat (P)
123-151 cm Lithofacies
TOP
0 3 6 9 12 1^ centimeters
Fig. 50. Photograph shows typical Peat (P) lithofacies.
107
study where the P Lithofacies was encountered were characterized by the Overwash
Radar Facies.
Correlation of Radar Facies and Lithofacies
Vibracores were used to “ground-truth” GPR data and help define the geologic
framework of relict-inlet channel fill and adjacent facies along the Outer Banks.
Correlation of lithofacies and radar facies was conducted by using a dielectric constant
(25) commonly used for saturated sands during the processing of GPR data. Reflections
seen in GPR data correlate well with abrupt contacts between lithofacies where there was
significant lithologic contrast. Correlations will be presented for areas where there were
both vibracores and interpretable GPR data at depths greater than ~2 m. A legend is
provided (Fig. 51) to explain lithofacies in core illustrations. Areas where vibracores
were acquired will be discussed in the following sections from north to south.
Rodanthe Non-Migrating/Complex Inlet
Figure 52 shows the location of RodIn-05-VCl taken within the town of
Rodanthe. GPR data in the area surrounding this core in Rodanthe revealed an
underlying non-migrating/complex inlet channel (Fig. 53) (named the Rodanthe Non-
Migrating/Complex Inlet). GPR data are characterized by large-scale channel cut and fill
patterns indicating that this area has been incised multiple times by inlet channels. A peat
horizon at -1.75 m depth below surface correlates well with a high amplitude slightly
108
Lithofacies Kev
Major Lithofacies Subfacies Symbols.•?.•.•?••.Shelly Sand (S
Sand(S) iT.'-'i (shelly)
)' T.v Laminated Sand(S(iam))
Shelly Gravelly Sand
*®^(shelly)* Rooted SandShelly Sandy Gravel (2(rtd))
*^*"($11611/)* ;i;^;.iGravelly Sand (gS) Massive Mud
Mud (M) •'.'?f-'V- Muddy Sand (mS) (^(mas))
Massively Bedded Sand Sandy Mud (sM)
Peat (P) (^(mas))
Fig. 51. Legend explains lithofacies illustrations as they occur in the following section.
75*28'0'W 75"27'30-W 75*27'0“W
»
35“36’30"N
Radar Sub-facies
? SNionng-leMiIgnrlaetting/
Rodanthe ?CNoomn-pMleigxraIntilnegt /
Non-Migrating/Complex ?CMoigmraptlienxg Inlet
as^asü'N Inlet i ? POevaetrwPalasthfoFrmlat/
?COhvaenrwnaesl h
?Poor/No Data
¡Active Inlet
Ki ometers
35*34 ?30''N
76*28-0’W 75'27'30'W 75*27*0’W
Fig. 52. A 2003 DOQQ (USGS) shows the location of the Rodanthe Non-Migrating/Complex Inlet and surrounding radar
facies. The green dot represents the site of the vibracore acquired within the non-migrating/complex inlet. The extent
of the GPR data shown in Fig. 53 is represented by the yellow line along NC Highway-12.
Fig. 53. GPR data with interpretations (red) shows the Rodanthe Non-migrating/Complex Inlet. The vibracore location
acquired within the non-migrating/complex inlet is shown. A legend for lithofacies is provided in Figure 51. Two
OSL ages are indicated.
Ill
sub-horizontal reflection (Fig. 53). Dipping clinoforms are present below the peat and
correlate well with Shelly Gravelly Sand and Shelly Sand sub-facies indicative of inlet-
fill (Fig. 53).
Salvo Complex Inlet
The Salvo Complex Inlet spans -1.75 km from the southern extent of the town of
Salvo to just south of the Salvo Day Use Area (Fig. 54). Eleven vibracores were taken
within and adjacent to the complex inlet. Locations for these cores and an additional
core, SalIn-05-VC2, taken in the town of Salvo within a separate complex inlet, are
shown in Figure 54. Shelly gravelly sands that fine upward to shelly sands and heavy
mineral laminated sands were encountered in cores taken from within the complex inlets.
These channel-fill sediments correlate well with dipping clinoforms in GPR data (Fig.
55-58). Reflections correlate well with lithologic contrasts between massive and/or
laminated sands and shelly gravelly sands within the inlet fill sediments.
Facies adjacent to the Salvo Complex Inlet were contained within vibracores
SalIn-05-VCl and SalIn-05-VClB taken just south of the southern edge of the complex
inlet (Fig. 59). These sediments represent the facies that the Salvo Complex Inlet incised
into. GPR data are poor at the location of these two vibracores and do not aid in the
environmental interpretation of these deposits.
75’30t)"W 75"2930‘W 75'29Ü*W 75*2B'30''W 75“28t)'W 75^7'30'W 75^7‘0'W 75‘’26'X*W
Kilometers
0 03 06 1.2 1.
35°3330-N
35“33'30-N GPR
Transect A
35*33'0‘N
Salln-05-VC2
35°33*0"N
36*3230-N
35*32’X'N
Radar Sub-facies
Salvo Day Use Non-Migrating/
^ 35”32t|-NArea Cores
35’32Ü"N 'GPR Salvo
Single Inlet
Transect B- /?'^COMPU.x ?CNoomn-pMleigxraIntilnegt /
Inlet ?CMoigmraptlienxg Inlet
I ?Overwash Flat/ 35*3130‘NPeat Platform35*31 '30’N Salln-05-VC1 ?COhveanvnaesl h
Salln-05-VC1B ^ , I Poor/No Data
Active Inlet
35*31 Ïl-N
75*28'X"W 75*28TD“W 75*2730 "W 75*27ü-W 76*2630‘W
Fig. 54. A 1998 DOQQ (USGS) shows the Salvo region. Locations are shown of vibracores (red) and two GPR transects
(yellow) that occur in Figure 55. The location of the Salvo Complex Inlet and other radar facies in the vicinity are
represented by colored blocks paralleling the Outer Banks.
GPR Transect A
Distance (m)
GPR Transe
Nine Salvo Day Use area
occur within the yellow lines
Fig. 55. GPR data are shown with interpretations (red) from two GPR transects in the Salvo region (Fig. 54). GPR Transect A
shows a complex inlet to the north of the Salvo Complex Inlet. GPR Transect B shows the Salvo Complex Inlet. The
locations of all vibracores (lithofacies legend in Fig. 51) acquired in the region are shown. Core logs for the nine
vibracores taken at the Salvo Day Use area are presented in figures 57 and 58. Vertical exaggeration = 70x.
114
Salln-05-VC2
D(empth)
AT .mzm rmi r^rM ? ? I iMTmmi
N S
Fig. 56. Vibracore SalIn-05-VC2 (lithofacies legend in Fig. 51) was obtained
within a relict complex inlet north of the Salvo Day Use area in the town
of Salvo (Fig. 54) and is projected on to the NC Highway-12 GPR data
(GPR Transect A in Figure 55). An OSL age is indicated.
SalvoDUA-05-S3B SalvoDUA-05-S4
SalvoDUA-05-S3\ / SalvoDUA-OS-SAB
Sal In-05- SalvoDUA-05-S2 SalvoDUA-05-S1
•r s
it
Fig. 57. Vibracores acquired in the Salvo Day Use area (lithofacies legend in Fig. 51) were acquired within the Salvo
Complex Inlet (Fig. 54) and projected on to the NC Highway-12 GPR data (GPR Transect B in Figure 55). An OSL
age is indicated.
SalvoDUA-05-S5 SalvoDUA-05-S5B
0.2
(D
Û
Fig. 58. Vibracores Salvo DUA-05-S5 and Salvo DUA-05-S5B (lithofacies legend in Fig. 51) were acquired within the
Salvo Complex Inlet (Fig. 54) and projected on to the NC Flighway-12 GPR data (GPR Transect B in Figure
55). An OSL age is indicated.
Fig. 59. Vibracores SalIn-05-VCl and SalIn-05-VClB (lithofacies legend in Fig. 51) were obtained from the southern
Salvo Day Use area (Fig. 54) and projected on to the NC Highway-12 GPR data (GPR Transect B in Figure 55).
Two OSL ages and two radiocarbon ages from these cores are indicated.
118
Kinnakeet Complex Inlet
Figure 60 shows the location of the Kinnakeet Complex Inlet and the three
vibracores acquired from the complex inlet. Vibracores KinnIn-05-Sl, KinnIn-05-VCl
and KinnIn-05-VC2 were obtained within the complex inlet and correlate well with
dipping clinoforms from GPR data (Fig. 61). Fining upward sequences within these two
cores match GPR reflections, suggesting multiple phases of inlet activity in the
evolutionary history of the Kinnakeet Complex Inlet. Vibracore KinnIn-05-Sl was taken
at the extreme northern edge of the complex inlet (Fig. 60) in an attempt to recover the
facies that the complex inlet incised into. Figure 62 shows the correlation of KinnIn-05-
S1 lithofacies with GPR data. The inlet-fill sediments from this core correlate well with
dipping reflections. The mS Sub-facies encountered at the bottom of the core in Figure
62 cannot be correlated due to data attenuation. However, this lithology is not
characteristic of inlet-fill and represents the facies adjacent to the Kinnakeet Complex
Inlet. KinnIn-05-VC2 (Fig. 62) and KinnIn-05-VCl (Fig. 63) acquired near the northern
and southern edges of the Kinnakeet Complex Inlet, respectively, contain lithologies
characteristic of inlet-fill.
Avon Complex Inlet
The location of the Avon Complex Inlet and the three vibracores acquired in the
region are shown in Figure 64. Vibracore AvonIn-05-VC3 was taken near the north edge
75’30‘30“W ZS^XtfW 75’29'X'W 75*29'0"W 75*20’X''W 75*2G'0"W
Kilometers
0 0.2 0.4 0.8 1.2
35*25'30'N
Radar Sub-facies
? SNionng-leMiIgnrlaetting/
35*25'0*N I CNoomn-pMleigxraIntilnegt /
Kmnln-05-S1 Migrating
Complex Inlet
Overwash Flat/
Kinnln-05-VC2 Peat Platform
Overwash
Kinnakeet Channel
Complex 35*24'X"N Poor/No Data
35^?4'30"N-
Inlet lActive Inleti
Kinnln-05-VC1
NC HW-12
GPR
35*24'0“N
35*24Ü‘N- Transect
75*3 rO”W 76*X3D'W 75*29?X"W 75*29t]"W 75*2eX’W 75*28?O’W
Fig. 60. A 1998 DOQQ (USGS) shows the Kinnakeet region. Locations of vibracores (red) and the NC Highway-12 GPR
transect (yellow) (Fig. 61) are shown. The location of the Kinnakeet Complex Inlet and other radar facies in the
vicinity are represented by colored blocks paralleling the Outer Banks.
.location of. location of
Fig. 62 Fig. 63 ?"
Kinnln-05-S1 Kinnln-05-VC2 Kinnln-05-VC1
1
?i
N Distance (m)
Fig. 61. GPR data with interpretations (red) shows the Kinnakeet Complex Inlet. The vibraeore locations (lithofacies legend
in Fig. 51 ) are shown within the complex inlet. Vertical exaggeration = 30x.
D(empth)
Fig. 62. Vibracores KinnIn-05-S and KinnIn-05-VC2 (lithofacies legend in Fig. 51) acquired from the northern edge of the
Kinnakeet Complex Inlet (Fig. 60) projected on to an enlarged section of NC Highway-12 GPR data. Three OSL ages
are indicated. Vertical exaggeration = 30x.
122
Kinnln-05-VC1
Fig. 63. Vibracore KinnIn-05-VCl (lithofacies legend in Fig. 51) acquired from the
southern edge of the Kinnakeet Complex Inlet (Fig. 60) and projected on to an
enlarged section of NC Highway-12 GPR data. Two OSL ages are indicated.
Vertical exaggeration = 30x.
75*3rX-W 75*3rO'W 75*X'3C'W 75*X'0‘W 75*29'30"W 75*29 T) ?W 75*28’X'W
Kilometers N 1
0 0.2 0.4 0.8 Mm
35*21 X"N
Avonln-05-VC3
Radar Sub-facies
Non-Migrating/
Single Inlet
.%*?! Ü'N Avon ?CNoomn-pMleigxraIntilnegt /
Complex ?CMoigmraptlienxg Inlet
Inlet ?OPevaetrwPalasthfoFrmlat/GPR
Transect B ?OChvearnwnaesl h
35*20X'N ?ij Poor/No Data
lActive Inlet
ivonln-05-VC1
ivonln-05-VC2
•35*20t)"N
35*20'0-N
75*31 X"W 75*31 •O'W 75*30X"W 75*30Ü'W 75*29TD’W
Fig. 64. A 1998 DOQQ (USGS) shows the Avon region. Locations of vibracores (red) and two GPR transects (Fig. 65) are
shown. The location of the Avon Complex Inlet and other radar facies in the vicinity are represented by colored blocks
paralleling the Outer Banks.
GPR Transect A
GPR Transect B location ofFig. 67 "
0
meters Q
Fig. 65. GPR data shown with interpretations (red) from two GPR transects in the Avon region (Fig. 67). GPR Transect A
shows the northern Avon Complex Inlet. GPR Transect B shows the southern Avon Complex Inlet. The location of
vibracores (lithofacies legend in Fig. 51) acquired in the region are shown
Avon I n-05-VC3
0
Fig. 66. Vibracore AvonIn-05-VC3 (lithofacies legend in Fig. 51) was obtained at the northern edge of the Avon Complex
Inlet (Fig. 64) and is projected on to an enlarged section ofNC Highway-12 GPR data. Two OSL ages are indicated.
126
of the complex inlet (Figs. 64, 65). The fining upward sequences present in these
vibracore sediments correlate with S dipping clinoforms (Fig. 66). Vibracores Avonin-
05-VCl and AvonIn-05-VC2 were acquired near the southern edge of the complex inlet
(Fig. 64, 65). One fining upward sequence was encountered and correlates well with N
dipping clinoforms (Fig. 67). Facies adjacent to channel-fill sediments of the Avon
Complex Inlet were not encountered in the vibracore sediments or GPR data.
Correlation of GPR and core data show that maximum penetration during
vibracoring often correlates with high amplitude dipping reflections (Fig. 65).
Penetration was often stopped when very coarse sediment was encountered at depth.
Ocracoke Island
Ocracoke Island typically produced some of the poorest and shallowest GPR data
in the study area. However, several inlet channels were distinguishable within the GPR
data (Fig. 68). Five vibracores were acquired on Ocracoke Island in the vicinity of
historic inlets and Inlet Radar Facies (Fig. 68). Vibracores OCR-05-S108-VC1 (Fig. 69),
OCR-05-S109-VC1 (Fig. 70), and OCR-05-S111 (Fig. 71) were taken in the vicinity of
historic Old Halteras Inlet according to Fisher (1962) (Table 1) (Fig. 10). GPR data were
attenuated at ~2.5 m in the area adjacent to these cores and only Overwash Radar Facies
could be correlated with vibracore sediments (Figs. 69, 70, 71). Vibracores OCR-05-
SllO-VCl and OCR-05- S112-VC1 (Fig. 72 and 73) were acquired on northeastern
Ocracoke Island at locations of Inlet Radar Facies (Fig. 68). However, only Overwash
Radar Facies were encountered in the data adjacent to vibracores (Figs. 68, 72, 73).
Avonln-05-VC2 Avonln-05-VC1
Fig. 67. Vibracores AvonIn-05-VCl and AvonIn-05-VC2 (lithofacies legend in Fig. 51) were obtained at the southern edge of
the Avon Complex Inlet (Fig. 64) and are projected on to an enlarged section of the NC Highway-12 GPR data. An
OSL age is indicated.
75“52’0'‘ W 75“51‘0" W 75‘’50‘0‘‘ W 75“49-0“ W 75M8‘0“ W
"
-95" 11‘ 0“ N
OCR-05-S112-VC1^
35* ir 0" N-
V Location of OCR-05-S110-VC1 :
Fig. 69 Í
'
^ s» -
-35* 10‘ 0“ N
35* 10‘ 0*' N- OCR-05-S111-VC1^
ocation oi
Location of w >Jajr^
Fio. 7Í 1' _ - i Location of
JAR SUB-FACIES
j SNionng-leMiIgnrlaetting/ ^5* 9‘ 0" N
OCR-05-S108-VC1
35” 9' 0" N- I CNoomn-pMleigxraIntilnegt /
? CMoigmraptlienxg Inlet
I OPevaetrwPalasthfoFrmlat/
] OChvearnwnaesl h
I Poor/No Data
¡Active Inlet -35” 8' O" N
35* 8‘ 0“ N- Kilometers
Location of
75"52'0” W 75*5r0“ w 75*50‘0“ W 75*49 0“ W 75*48'0“ W
Fig. 68. A 1998 DOQQ (USGS) shows northeastern Ocracoke Island. Locations of vibracores (red) are shown. Radar facies
are represented by colored blocks paralleling the Outer Banks. Locations of detailed GPR and vibracore illustrations in
Figures 69 to 73 are represented by green squares on the island.
129
OCR-05-S108-VC1
(Dempth)
sw
Fig. 69. Vibracore OCR-05-S108-VC1 (lithofacies legend in Fig. 51) was
obtained from the northern Pony Pasture area on northeastern Ocracoke
Island (Fig. 68) and is projected on to NC Highway-12 GPR data. An
OSL age is indicated.
130
OCR-05-S109-VC1
Fig. 70. Vibracore OCR-05-S109-VC1 (lithofacies legend in Fig. 51) was
obtained from the southern Pony Pasture area on northeastern Ocracoke
Island (Fig. 68) and is projected on to NC Highway-12 GPR data. An
OSL age is indicated.
131
D(empth)
Fig. 71. Vibracore OCR-05-S111-VCl (lithofacies legend in Fig. 51) was
obtained from the central Pony Pasture area on northeastern Ocracoke Island (Fig.
68) and is projected on NC Highway-12 GPR data.
132
OCR-05-S110-VC1
(Dempth)
Fig. 72. Vibracore OCR-05-S110-VCl (lithofacies legend in Fig. 51) was
obtained from northeastern Ocracoke Island (Fig. 68) and is projected on
to NC Highway-12 GPR data. An OSL age is indicated.
133
OCR-05-S112-VC1
Fig. 73. Vibracore OCR-05-S112-VCl (lithofacies legend in Fig. 51) was
obtained from northeastern Ocracoke Island (Fig. 68) and is projected on
NC Highway-12 GPR data.
134
Foraminiferal Assemblages
Fifty-three samples from 18 vibracores were used in the analysis of biofacies in
the field area. Thirty-nine samples contained foraminifera and fourteen samples were
barren. Thirty-five benthic taxa were identified to at least the generic level. Two
planktonic specimens were recovered. Foraminifera specimens from inlet-fill sediments
were commonly sorted (presumably by wave energy) and deposited as sedimentary
particles. These specimens were often etched due to reworking of tests within sandy
deposits.
In order to determine biofacies, a Q-mode cluster analysis was conducted (Mello
and Buzas, 1968). Only species representing greater than 2% of the total assemblage in
any one sample were included in the cluster analysis (Appendix B). The foraminiferal
data were further reduced by excluding samples with less than fifteen specimens. Using
the equation;
2arcsinVp
(p = abundance)
abundance data for each species were transformed (Appendix G). The transformed data
were used in cluster analysis to distinguish groups containing similar foraminiferal
assemblages.
The cluster analysis distinguished four biofacies containing nineteen samples and
twenty-four taxa (Fig. 74) (Appendix G). Constancy (C), occurrence (O), and biofacies
fidelity (BF) were calculated to determine contribution of each species to each biofacies
135
Biofacies Sample
OCR-05-S111 151-152cm 36 3
OCR-05-S108 416-417cm 18 11
OCR-05-S112 116-117cm 29 10
2 OCR-05-S111 320-321cm 52 7
OCR-05-S110 151-152cm 27 5
OCR-05-S108 445-446cm 15 4
OCR-05-S108 309-310cm 279 6
Kinnln-05-VC1 155-156cm 22 2
3 OCR-05-S109 505-506cm 22 10
Oreln-06-VC1 132-133cm 15 2
SalvoDUA-05-S3B 317-318cm 15 3
Salln-05-VC1 503-504cm 121 8
Kinnln-05-S1 288-289cm 320 7
Kinnln-05-VC2 209-210cm 70 7
A OCR-05-S108 281-282cm 244 13
4 OCR-05-S110 475-476cm 276 14
OCR-05-S110 304-305cm 159 15
OCR-05-S112 275-276cm 143 14
OCR-05-S109 203-204cm 86 9
0 0.5 1 1.5 2
Euclidean Distances
Samples not included in cluster analysis:
Samples with <15 specimens per sample Samples barren of foraminifera
Avonln-05-VC2 197-198cm 9 3 Avonln-05-VC2 90-91cm
Avonln-05-VC3 135-136cm 13 4 Kinnln-05-S1 114-115cm
Avonln-05-VC3 229-230cm 14 4 Kinnln-05-VC1 33-84cm
Kinnln-05-S1 189-190cm 3 3 Kinnln-05-VC2 66-67cm
Kinnln-05-VC1 235-236cm 3 1 OCR-05-S108 193-194cm
Kinnln-05-VC2 143-144cm 2 1 OCR-05-S108 281-282cm
OCR-05-S108 71-72cm 2 1 OCR-05-S109 488-489cm
OCR-05-S108 120-121cm 1 1 Rodln-05-VC1 169-170cm
OCR-05-S109 434435cm 14 4 SalvoDUA-05-S1 98-99cm
OCR-05-S111 63-64cm 9 4 Salln-05-VC1 84-85cm
Oreln-06-VC1 364-365cm 14 4 Salln-05-VC1 104-105cm
Rodln-05-VC1 197-198cm 1 1 Salln-05-VC1 221-222cm
Rodln-05-VC1 292-293cm 7 1 Salln-05-VC1 279-280cm
SalvoDUA-05-S1 184-185cm 8 2 Salln-05-VC1 334-335cm
SalvoDUA-05-S5B 124-125cm 5 2 Salln-05-VC1 395-396cm
SalvoDUA-05-S5B 216-217cm 3 2
Salln-05-VC2 112-113cm 10 4
Salln-05-VC2 258-259cm 13 1
Salln-05-VC3 106-107cm 6 2
Salln-05-VC3 402-403cm 3 2
Fig. 74. Dendrogram results derived from cluster analysis (Ward’s linkage, Euclidean
distances) of foraminiferal data.
136
(Table 4). C and BF values that are boxed in Table 4 indicate characteristic species to the
foraminiferal assemblage. These characteristic species were arbitrarily defined having
BF values > 5 and C values > 6.
In an attempt to correlate grain size and foraminiferal facies, a grain size cluster
analysis was carried out on samples that were included in the cluster analysis performed
on transformed abundances of foraminifera taxa. The grain size cluster analysis (Fig. 75)
was compared to the foraminifera cluster analysis and no significant correlations were
observed that would aid in the interpretation of paleoenvironments.
Biofacies 1
Biofacies 1 was present in only one sample approximately 1.5 m below the
surface in the area of historic Old Halteras Inlet according to Fisher (1962) on NE
Ocracoke Island. This sample was encountered within the Muddy Sand Sub-facies and
contained roots. This biofacies is characterized by Trochammina inflata,
Haplophragmoides wilberti, and Haplophragmoides sp.
Biofacies 2
Biofacies 2 was present in five samples from various depths ranging from 1.16-
4.46 m below surface on northeastern Ocracoke Island. It was not found at other
localities. This biofacies was mostly encountered in coarser sediments with a minor
occurrence in finer sands. This biofacies contains 9 species (Table 4). Only Cibicides
lobatulus is defined as a characteristic species of this biofacies.
137
Biofacies
1 2 3 4
Species O c BF O C BF O C BF O C BF
Ammonia parkinsoniana 0 0 0 1 2 1 3 6 3 8 10 6
Asterigerina carinata 0 0 0 3 6 5 0 0 0 4 5 5
Buccella inusitata 0 0 0 1 2 2 0 0 0 6 8 8
Cibicides lobatulus 0 0 0 4 8 5 1 2 1 5 6 4
Elphidium excavatum 0 0 0 5 10 3 5 10 4 8 10 3
Elphidium galvestonense 0 0 0 5 10 4 2 4 2 7 9 4
Elphidium gunteri 0 0 0 3 6 4 0 0 0 6 8 6
Elphidium macellum 0 0 0 0 0 0 0 0 0 3 4 10
Elphidium mexicanum 0 0 0 2 4 3 0 0 0 6 8 7
Elphidium sp. 0 0 0 1 2 6 0 0 0 1 1 4
Elphidium subarcticum 0 0 0 1 2 2 0 0 0 6 8 8
Eponides répandus 0 0 0 1 2 6 0 0 0 1 1 4
Eponides sp. 0 0 0 1 2 10 0 0 0 0 0 0
Hanzawaia strattoni 0 0 0 1 2 1 3 6 3 8 10 6
Haplophragmoides sp. 1 10 10 0 0 0 0 0 0 0 0 0
Haplophragmoides wilberti 1 10 8 1 2 2 0 0 0 0 0 0
Haynesina germánica 0 0 0 0 0 0 1 2 6 1 1 4
Indeterminate rotaliid 0 0 0 0 0 0 0 0 0 1 1 10
Nonionella atlántica 0 0 0 1 2 2 0 0 0 5 6 8
Quinqueloculina jugosa 0 0 0 1 2 4 0 0 0 2 3 6
Quinqueloculina lamarckiana 0 0 0 0 0 0 0 0 0 2 3 10
Quinqueloculina seminula 0 0 0 3 6 4 0 0 0 6 8 6
Quinqueloculina sp. 0 0 0 1 2 6 0 0 0 1 1 4
Trochammina inflata 1 10 8 1 2 2 0 0 0 0 0 0
No. of taxa in cluster group 3 19 6 20 1
Table. 4. Foraminiferal occurrence (O), constancy (C), and biofacies fidelity (BF) values
for biofacies defined by cluster analysis. Boxed values indicate values for C>6
and BF>5.
138
Cluster
Group Sample
OCR-05-S108 309-310cm 3 ^®(bur)
OCR-05-S111 151-152cm 1
A Kinnln-05-S1 288-289cm 4 ^®(bur)
OCR-05-S108 281-282cm 4 ^®(bur)
OCR-05-S110 475-476cm 4 ®(mas)
OCR-05-S111 320-321cm 2 (bur)
OCR-05-S108 416-417cm 2 ^(shelly)
Kinnln-05-VC1 155-156cm 3 >1^(lam)
B OCR-05-S110 304-305cm 4 ^(mas)
Salln-05-VC1 503-504cm 4 ^(mas) ?
OCR-05-S109 505-506cm 3 '^^(bur) ?
OCR-05-S108 445-446cm 2 rnS(ry) .
OCR-05-S110 151-152cm 2 ^(shelly)
OCR-05-S112 275-276cm 4 ^(shelly) •
OCR-05-S109 203-204cm 4 9®(shelly)3|_T,
OCR-05-S112 116-117cm 2 9^(shelly)
Kinnln-05-VC2 209-210cm 4 9®(shelly)
SalvoDUA-05-S3B 317-318cm 3 9S(shellyl1y)—U
Oreln-06-VC1 132-133cm 3 9^(shelly]
^ r
0 0.5 1 1.5
Euclidean Distances
Samples not included in cluster analysis
Avonln-05-VC2 90-91 cm Rodln-05-VC1 169-170cm
Avonln-05-VC2 197-198cm Rodln-05-VC1 197-198cm
Avonln-05-VC3 135-136cm Rodln-05-VC1 292-293cm
Avonln-05-VC3 229-230cm Salln-05-VC1 84-85cm
Kinnln-05-S1 114-115cm Salln-05-VC1 104-105cm
Kinnln-05-S1 189-190cm Salln-05-VC1 221-222cm
Kinnln-05-VC1 83-84cm Salln-05-VC1 279-280cm
Kinnln-05-VC1 235-236cm Salln-05-VC1 334-335cm
Kinnln-05-VC2 66-67cm Salln-05-VC1 395-396cm
Kinnln-05-VC2 143-144cm Salln-05-VC2 112-113cm
OCR-05-S108 71-72cm Salln-05-VC2 258-259cm
OCR-05-S108 120-121 cm Salln-05-VC3 106-107cm
OCR-05-S108 193-194cm Salln-05-VC3 402-403cm
OCR-05-S108 281-282cm SalvoDUA-05-S1 98-99cm
OCR-05-S109 434-435cm SalvoDUA-05-S1 184-185cm
OCR-05-S109 488-489cm SalvoDUA-05-S5B 124-125cm
OCR-05-S111 63-64cm SalvoDUA-05-S5B 216-217cm
Oreln-06-VC1 364-365cm
Fig. 75. Dendrogram results derived from cluster analysis (Ward’s linkage, Euclidean
distances) of grain size data. Supplementary biofacies and lithofacies data are
provided in columns adjacent to the dendrogram. The grain size cluster analysis
was performed only on samples included in the foraminifera cluster analysis in an
attempt to correlate between the two and to aid in paleoenvironmental
interpretations.
139
Biofacies 3
Biofacies 3 was present in five samples at depths ranging from 1.32-5.06 m at
Oregon Inlet, Ocracoke Island, Kinnakeet, and the Salvo Day Use area. This biofacies
was encountered in gS(sheiiy), S(iani), and mS(bur) Sub-facies. This biofacies has lower
diversity (Table 4) and fewer specimens (Fig. 74) than Biofacies 2 and 4. No taxa met
the arbitrary criteria for characteristic species.
Biofacies 4
Biofacies 4 was present in eight samples at depths ranging from 2.02-5.04 m at
Kinnakeet, the Salvo Day Use area, and NE Ocracoke Island. This biofacies contained
20 taxa (Table 4) and had the most specimens per sample (Fig. 74). Biofaces 4 was
encountered in gS(sheiiy)> S(sheiiy), S(nias), and mS Sub-facies. Twenty species were defined
as characteristic of the biofacies: Elphidium excavatum, Ammonia parkinsoniana,
Hanzawaia strattoni, Elphidium galvestonense, Quinqueloculina seminula, Elphidium
mexicanum, Buccella inusitata, Elphidium subarcticum, Elphidium gunteri, Nonionella
atlántica, Cibicides lobatulus, Asterigerina carinata, Elphidium macellum,
Quinqueloculina lamarckiana, Quinqueloculina jugosa. Indeterminate rotaliid,
Haynesina germánica, Elphidium sp., Eponides répandus, and Quinqueloculina sp.
140
Correlation of Radar Facies, Lithofacies, and Biofacies
Radar facies, lithofacies, and biofacies were correlated to interpret paleo-
depositional environments for relict-inlets and adjacent facies along the Outer Banks.
Correlations resulted in four Radar-Litho-Bio Facies (RLBF) being defined. These four
facies were divided into multiple sub-facies on which paleoenvironmental interpretations
were made (Table 5).
Radar-Litho-Bio Facies 1 (RLBF-1)
RLBF-1 consisted of one sample (Table 5). The paleoenvironmental
interpretation for RLBF-1 is low energy estuarine environment/estuarine shoal. This
facies is characterized by the presence of a typical marsh foraminiferal assemblage,
poorly sorted, rooted muddy sand lithology with mean grain size of 2.91 0, and high
amplitude horizontal reflectors. This facies does not contain sufficient organic material
to permit interpretation as a salt marsh. It is interpreted, therefore, to be within the
estuary but near a salt marsh from which marsh foraminifera were derived. RLBF-1
occurred in one sample from OCR-05-S111 (Appendix E) acquired from the central Pony
Pasture area on northeastern Ocracoke Island (Fig. 68).
Mean Radar-Litho-Bio Facies/
Foraminifera
BF LF Grain Sizes Sorting Geophysical Paleoenvironmental(^% abundance per sample)**
(Phi) Geometry Interpretation
Trochammina inflata, High-amplitude,
1 RLBF 1: LowHaplophragmoides wilberti, ntS(rtd) 2.91 [2.91] P horizontal energy estuarineenvironment/Estuarine shoal
Haplophragmoides sp. reflections
Elphidium excavatum, Elphidium 1.74-1.89 Horizontal.
galvestonense, Cibicides lobatulus, §S(shelly)i M-P RLBF 2-a: Overwash
Quinqueloculina seminula, Asterigerina S(shelly) [1.82] reflections
carinata, Elphidium gunteri, Elphidium S(shelly) 1.91 [1.91] MW No/poor data RLBF 2-b: Inlet Channelmexicanum, Eponides sp.,Eponides répandus,
2 Elphidium sp , Quinqueloculina
sp., Quinqueloculina jugosa, Elphidium
subarcticum, Haplophragmoides wilberti, tnS(rtd), 1.96-2.23 RLBF 2-c: LowW-MW energy estuarine
Buccella inusitata, Nonionella atlántica, [2.10] No/poor dataS(bur) environment/Flood tide delta
Trochammina inflata. Ammonia parkinsoniana,
Hanzawaia strattoni
S(lam)i 1.49-1.85 P Steeply dipping RLBF 3-a; Inlet Channel
Elphidium excavatum. Ammonia ê^fshellv) [1.67] clinoforms
3 parkinsoniana, Hanzawaia strattoni, Elphidium Horizontalgalvestonense, Haynesina germánica, ê^(shclly) 1.34 [1.34] P RLBF 3-b: Overwashreflections
Cibicides lobatulus
2.21-3.31 RLBF 3-c: Low
^^^(bur) MW-P energy estuarine[2.76] No/poor data environment/Flood tide delta
Elphidium excavatum. Ammonia
parkinsoniana, Hanzawaia strattoni, Elphidium 1.81-1.87ê^Cshelly) M-P Steeply dipping RLBF 4-a: Inlet Channel
galvestonense, Quinqueloculina seminula, 11.84] clinoforms
Elphidium mexicanum, Buccella inusitata,
Elphidium subarcticum, Elphidium gunteri, S(shelly), 1.97-2.10 Horizontal.M-W RLBF 4-b: Overwash
4 Nonionella atlántica, Cibicides lobatulus, Simas) [2.04] reflections
Asterigerina carinata, Elphidium macellum, 2.16-2.47 RLBF 4-c:MW-W
Quinqueloculina lamarckiana, Quinqueloculina S(mas) [2.32] No/poor data
High energy open
marine environment/Inlet channel
jugosa, Indeterminate rotaliid, Haynesina ^S^shelly 2.42-2.67 RLBF 4-d: Lowgermánica, Elphidium sp., Eponides répandus, MW-W No/poor data energy estuarine
Quinqueloculina sp. [2.55] environment/Flood tide delta
Table 5. Table summarizes radar, litho- (LF), and bio-facies data (BF). Correlation of these parameters resulted in four Radar-
Litho-Bio Facies (RLBF) and ten sub-facies used in making paleoenvironmental interpretations. Average mean grain
size values are bracketed. Sorting values P, M, MW, and W represent poorly, moderately, moderately well, and well,
respectively.
142
Radar-Litho-Bio Facies 2 (RLBF-2)
RLBF-2 was subdivided into three sub-facies based on lithology and geophysical
geometry. The three sub-facies consist of the same foraminiferal assemblage and were
subdivided based on lithology and geophysical geometry (Table 5).
Overwash (RLBF 2-a). The RLBF 2-a sub-facies is characterized primarily by
chaotic GPR data and horizontal reflections of the Overwash Radar Facies. Sediments of
this sub-facies are typically coarse with an abundance of shell material. These
characteristics are common of modem overwash deposits. RLBF 2-a was encountered in
two samples from vibracores OCR-05-S110 (Appendix E) and OCR-05-S112 (Appendix
E) on northeastern Ocracoke Island (Fig. 68).
Inlet Channel (RLBF 2-b). The RLBF 2-b sub-facies lacks discernible GPR data
therefore making the foraminiferal assemblage and lithology the distinguishing
characteristics. It is characterized by an inner-shelf foraminiferal assemblage and coarse,
moderately well sorted shelly quartz sands. These characteristics allow for a
paleoenvironmental interpretation of inlet channel. RLBF 2-b was encountered in one
sample from vibracore OCR-05-S108 (Appendix E) at the northern part of the Pony
Pasture area on northeastern Ocracoke Island (Fig. 68).
Low Energy Estuarine Environment/Flood Tide Delta (RLBF 2-c). The RLBF 2-c
sub-facies is similar to RLBF 2-b in that it lacks discernible GPR data and contains a
similar foraminiferal assemblage. The distinguishing characteristic for this sub-facies is
the rooted muddy sand and burrowed sand lithologies. These sediments are not
encountered within the inlet channel (or inlet “throat”), but are encountered on lower
143
energy estuarine environments adjacent to the inlet, such as a flood tide delta or estuarine
shoal. RLBF 2-c was encountered in two samples from vibracore OCR-05-S108
(Appendix E) and OCR-05-S111 (Appendix E) in the Pony Pasture area on northeastern
Ocracoke Island (Fig. 68).
Radar-Litho-Bio Facies 3 (RLBF-3)
The RLBF-3 Facies primarily differs from the other three facies by its
foraminiferal assemblage. This facies is characterized by lower taxonomic diversity than
the inner-shelf assemblages of RLBF-2 and RLBF-4 (Table 5). RLBF-3 was subdivided
into three sub-facies based on lithology and geophysical geometry. The same three
paleoenvironmental interpretations were made on these sub-facies as for the RLBF-2 sub-
facies.
Inlet Channel (RLBF 3-a). The RLBF 3-a sub-facies is primarily defined by
dipping clinoforms present in GPR data and indicative of Inlet Radar Facies. Poorly
sorted, heavy mineral laminated sands and shelly gravelly sands were encountered in this
sub-facies. These characteristics along with a low diversity inner shelf foraminiferal
assemblage warrant a paleoenvironmental interpretation of inlet channel. RLBF 3-a was
encountered in two samples from vibracores KinnIn-05-VCl (Appendix E) and SalDUA-
05-S3B (Appendix E) on the northern edge of the Kinnakeet Complex Inlet (Fig. 60) and
the Salvo Day Use Area (Fig. 54), respectively.
Overwash (RLBF 3-b). The RLBF 3-b sub-facies contains the same lithology and
foraminiferal assemblage as the RLBF 3- a sub-facies. It differs in continuous horizontal
144
GPR data characteristic of the Overwash Radar Facies. One sample from vibracore
OreIn-06-VCl (Appendix E) acquired to the north of the modem location of Oregon Inlet
(Fig. 39) contained the RLBF 3-b Sub-facies.
Low Energy Estuarine Environment/Flood Tide Delta (RLBF 3-c). The RLBF 3-c
sub-facies lacks discernible GPR data and has a lithology similar to that encountered in
the RLBF 2-c sub-facies from which it differs in its less diverse foraminiferal
assemblage. Three samples from vibracores OCR-05-S108 (Appendix E) (Fig. 68),
OCR-05-S109 (Appendix E) (Fig. 68), and SalIn-05-VCl (Appendix E) (Fig. 54)
contained the RLBF 3-c sub-facies.
Radar-Litho-Bio Facies 4 (RLBF-4)
RLBF-4 is the most widely occurring facies. Samples comprising this facies
contain more specimens and generally more inner-shelf foraminiferal species than RLBF-
2 and RLBF-3. This facies is divided into four sub-facies based on lithology and
geophysical data (Table 5).
Inlet Channel (RLBF 4-a). RLBF 4-a is similar to RLBF 2-b and RLBF 3-a (both
Inlet Channel paleo-depositional environment interpretations) lithologically and
geophysically. The distinguishing characteristic of this sub-facies is its more diverse
inner shelf foraminiferal assemblage. RLBF 4-a was encountered in two samples from
vibracores KirmIn-VC2 (Appendix E) acquired on the north edge of the Kinnakeet
Complex Inlet (Fig. 60) and OCR-05-S109 (Appendix E) from the southern Pony Pasture
area on northeastern Ocracoke Island (Fig. 68).
145
Overwash (RLBF 4-b). This sub-facies contains similar lithology and geophysical
geometry to RLBF 2-a and RLBF 3-b (both interpreted as overwash). The distinguishing
characteristic of this sub-facies is its more diverse inner shelf foraminiferal assemblage.
Two samples from vibracores OCR-05-S110 (Appendix E) and OCR-05-S112 (Appendix
E) from northeastern Ocracoke Island (Fig. 68) contained the RLBF 4-b Sub-facies.
Hish Enersv Estuarine Environment/Inlet Channel (RLBF 4-c). RLBF 4-c does
not have interpretable GPR data and therefore litho- and bio-facies data must be used to
make paleoenvironmental interpretations. This sub-facies is characterized by moderately
well to well sorted, coarse, massively bedded quartz sand and a diverse inner shelf
foraminiferal assemblage. The paleo-depositional environment of RLBF 4-c is
interpreted as a high energy environment adjacent to inlet rather than “inlet channel”
because sub-facies interpreted as forming in an inlet channel contain coarser sediments
composed of more shell material than RLBF 4-c. RLBF 4-c was encountered in one
sample from vibracore OCR-05-S110 (Appendix E) on the northeastern end of Ocracoke
Island (Fig. 68).
Low Enersv Estuarine Environment/Flood tide delta (RLBF 4-d). RLBF 4-d
differs from RLBF 4-c in its finer lithology. RLBF 4-d is characterized by muddy sands
(with shells and/or burrows) that are characteristic of low energy environments such as
flood tide deltas and estuarine shoals. This lithology is not encountered in high energy
inlet channel environments. However, due to the lack geophysical evidence, the general
paleoenvironmental interpretation of “low energy estuarine environment/flood tide delta”
is used. This sub-facies was encountered in two samples from vibracores KirmIn-05-Sl
146
(Appendix E) from the extreme north edge of the Kirmakeet Complex Inlet (Fig. 60) and
OCR-05-S108 (Appendix E) from the northern Pony Pasture area on northeastern
Ocracoke Island (Fig. 68).
Age Data
Radiocarbon Age Estimates
The results of the AMS analyses are provided in Table 6. Both samples were
taken from vibracore SalIn-05-VClB directly south of the Salvo Complex Inlet.
Analyses were made on an organic layer at -0.4 m below MSL and an in situ articulated
Chione cancellata shell within a sandy mud unit at -2.1 m below MSL. The two
lithologic units sampled are representative of facies adjacent to the Salvo Complex Inlet
(Fig. 54). The organic layer returned an age estimate of 291 to 221 calibrated yrs. B.P.
The articulated bivalve returned an age estimate of 1526 to 1356 calibrated yrs. B.P.
These age estimates are in agreement with OSL ages from different facies above and
below both radiocarbon samples from vibracore SalIn-05-VCl, which was taken <1 m
away from SalIn-05-VClB.
DEPTH Sample D C Radiocarbon 2 SiG. Cal.CORE MSL Description (0/00) Age (years) Range (yrs bp)
SalIn-OS-VC 1 B -0.4 M Peat -22.49 265±35 291-221
SalIn-05-VCIB -2.1 M Chione cancellata -1.13 1900±30 1526-1356
Table 6. AMS '^’C age estimates are shown. ’‘^C Calibration is based on Stuiver and Reimer (1993).
148
Luminescence Age Estimates
Luminescence dating was utilized on relict inlet channel-fill and adjacent facies at
selected sites from Oregon Inlet to Ocracoke Inlet (Table 7). To confirm the use of OSL
on quartz sands deposited in shallow marine environments, two “proof of concept”
samples (Orein 2.98-3.16 and Orein 3.16-3.41) were obtained from the lithologic units
that comprise the prograding spit platform of Oregon Inlet where the géomorphologie
evolution is well documented by historic maps and aerial photos. Orein 2.98-3.16 and
Orein 3.16-3.41 dated shelly sands that were deposited shortly after the inception of
Oregon Inlet in 1846 A.D. and returned expected ages of 124 ± 21 and 170 ± 29 yrs. B.P.
These dates agree with the historical evolution of Oregon Inlet and validate the use of
luminescence dating on inlet-fill quartz sands.
Fourteen luminescence samples were obtained from relict inlet chaimel-fill sands
from the Avon, Salvo, and Kinnakeet Complex Inlets, a migrating complex inlet in the
town of Salvo to the north of the Salvo Complex Inlet, and the Rodanthe Non-
Migrating/Complex Inlet (Table 7) (Figs. 9, 10). The OSL ages revealed different
depositional phases for the relict inlets.
Charmel-fill sand from the Avon Complex Inlet was dated with three samples
(AvonIn-VC2 1.95-2.10, AvonIn-VC3 1.45-1.60, and AvonIn-VC3 2.41-2.56) producing
similar ages that ranged from 448 to 273 yrs. B.P (Table 7). Two samples (SalvoDUA-
S3B 4.06-4.21 and Salvo DUA-S5B 2.86-3.06) dated Salvo Complex Inlet chaimel-fill
sands returned similar ages and ranged from 553 to 324 yrs. B.P. (Table 7). Five samples
(KinnIn-VCl 1.60-1.75, KinnIn-VCl 2.38-2.54, KinnIn-VC2 1.45-1.60, KinnIn-VC2
149
Sample Moisture Quartz Dose Rate Equivalent Quartz OSL
(depth in m below sfc.) (%)“ (IO'^Gy/yr) Dose (Gy) AGE (yr)'^
AvonIn-VC2 (1.9&-2.10) 20 + 1 13 (18) 0.46 ± 0.04 0.18 + 0.01 383 ± 45
AVONIN-VC3 (1.45-1.60) 11 ± 1 12(38) 0.51 ± 0.05 0.20 ± 0.01 396 ± 44
AVONIN-VC3 (2.41-2.56) 20 ± 1 11 (20) 0.59 ± 0.09 0.19 ± 0.01 330 ± 57
KinnIn-VCI (1.60-1.75) 16 ± 1 15(28) 1.04 ± 0.03 0.39 ± 0.02 379 ± 20
KinnIn-VCI (2.38-2.54) 18 ± 1 19 (20) 0.63 ± 0.08 0.29 ± 0.01 453 ± 56
KINNIN-VC2 (1.45-1.60) 12 ± 1 13(20) 0.20 ± 0.03 0.49 ± 0.05 410 + 48
KINNIN-VC2 (2.12-2.28) 10 ± 1 15(24) 0.57 ± 0.04 0.68 ± 0.05 1192 ± 120
KINNIN-SI (2.552.78) 7 ± 1 19 (30) 0.69 ± 0.03 0.25 ± 0.06 362 ± 21
OCR-S108 (4.60-4.75) 21 ± 1 19 (30) 1.48 ± 0.03 0.65 ± 0.02 442 ± 34**
OCR-S109 (5.255.40) 21 ± 1 17(30) 0.88 ± 0.03 1.55 ± 0.03 1761 ± 142‘'
OCR-S110 (4.80-4.95) 23 ± 1 5(18) 0.93 ± 0.04 0.18 ± 0.03 199 ± 79*’
OREIN (2.98-3.16) 19 ± 1 17(24) 0.84 ± 0.03 0.11 ± 0.01 124 ± 21
OREIN (3.153.41) 11 ± 1 17(20) 0.77 ± 0.03 0.14 ± 0.01 170 ± 29*’
Rodin (2.00-2.15) 17 ± 0.5 20 (25) 1.39 ± 0.05 0.42 ± 0.01 305 ± 28
RodIn (4.44-4.59) 19 ± 0.5 11 (14) 1.07 ± 0.05 0.84 ± 0.02 786 ± 90
SalIn-VCI (2.552.71) 27 ± 0.5 14 (24) 1.30 ± 0.05 0.76 ± 0.03 600 ± 76
SalIn-VCI (5.155.31) 20 ± 1 15 (24) 0.85 ± 0.06 1.72 ± 0.05 2019 ± 144
SALIN-VC2 (1.151.30) 4 ± 1.5 21 (24) 0.48 ± 0.04 0.23 ± 0.02 473 ± 52
SALVODUA-S3B (4.054.21) 19 ± 0.5 5(20) 0.52 ± 0.03 0.26 ± 0.2 499 + 54
SALVODUA-S5B (2.86-3.06) 14 + 1 19 (35) 0.55 ± 0.05 0.21 ± 0.02 376 ± 52
®Field moisture, ages based on 15-25% moisture content through time as an average between field and saturation moisture values.
‘^Number of repicated equivalent dose (De) estimates used to calculate the mean. Figures in parentheses indicate total number of
measurements made including failed runs with unusable data.
^Lab used fine sand grains (250-180 micron size) tor Blue-Light OSL as single aliquot regeneration technique (SAR). Quoted errors
are one sigma.
'’Lab used fine sand grains (180-150 micron size) for Blue-Light OSL as single aliquot regeneration technique (SAR).
Table 7. Table summarizes OSL age estimates and laboratory notes are provided.
150
2.12-2.28, and Kinnin-Sl 2.55-2.78) dated channel-fill sand from the Kinnakeet Complex
Inlet and produced four similar ages that ranged from 509 to 341 yrs B.P. (Table 7) and
one older age that ranged from 1312 to 1072 yrs. B.P. (Table 7). Charmel-fill sand from
a migrating complex inlet in Salvo, north of the Salvo Complex Inlet, was dated with one
sample (SalIn-VC2 1.15-1.30) and produced an age estimate of 525 to 421 yrs. B.P.
(Table 7). Sample Rodin 4.44-4.59 dated channel-fill sands from the Rodanthe Non-
Migrating/Complex Inlet and returned an age of 1056 to 876 yrs. B.P. (Table 7).
Samples were also obtained from facies adjacent to relict inlet chaimel-fill from
the Salvo and Rodanthe areas and Ocracoke Island (Fig. 1). Two samples (Salln-VCl
2.56-2.71 and Salln-VCl 5.15-5.31) from SalIn-05-VCl, a vibracore obtained just south
of the Salvo Complex Inlet (Fig. 9), dated a burrowed muddy sand unit at 2.56-2.71 m
depth below surface and a shelly sand at 5.15-5.31 m depth below surface. These two
lithologies were interpreted to be deposited in low and high energy environments
adjacent to an inlet, respectively (Appendix E). Sample Salln-VCl 2.56-2.71 returned an
age of 676 to 524 yrs. B.P. (Table 7). Sample Salln-VCl 5.15-5.31 returned an age of
2163 to 1875 yrs. B.P., the oldest OSL date obtained in this study (Table 7).
One sample (Rodin 2.00-2.15) from RodIn-05-VCl, a vibracore acquired within
the Rodanthe Non-Migrating Complex Inlet (Fig. 9), sampled a rooted sand unit at 2.00-
2.15 m depth beneath the surface and returned and age that ranged from 333 to 277 yrs.
B.P. The rooted sand lithology dated was interpreted to be deposited adjacent to a salt
marsh (Appendix E).
151
Three samples (OCR-S108 4.60-4.75, OCR-S109 5.25-5.40, and OCR-Sl 10 4.80-
4.95) were obtained from different cores on Ocracoke Island (Fig. 1) and sampled facies
adjacent to relict inlet channel-fill. Sample OCR-S108 at 4.60-4.75 m from OCR-05-
S108-VC1 on northeastern Ocracoke Island (Fig. 71) dated a rooted muddy sand unit and
returned an age of 476 to 408 yrs B.P. (Table 7). This sample was interpreted to be a low
energy environment adjacent to an inlet (flood tide delta/estuarine shoal) (Appendix E).
Sample OCR-S109 at 5.25-5.40 m from OCR-05-S109-VC1 on northeastern Ocracoke
Island (Fig. 71) dated a shelly sand unit and returned an age of 1903 to 1619 yrs. B.P.
(Table 7). This sample was interpreted to be deposited in a high energy environment
adjacent to an inlet (Appendix E). Sample OCR-Sl 10 at 4.80 to 4.95 m from OCR-05-
SI 10-VCl on northeastern Ocracoke Island (Fig. 71) dated a massively bedded sand unit
and returned an age of 278 to 120 yrs. B.P. (Table 7). This sample was interpreted to be
deposited in a high energy environment adjacent to an inlet (Appendix E).
152
DISCUSSION
Classification of Inlets
Shore-parallel GPR data acquired on North Carolina HW-12 revealed that
approximately 40% of the shallow (<7 m) geologic framework underlying the Outer
Banks from Oregon Inlet to Ocracoke Inlet contained inlet channel geometries (Figs. 8,
12). Since -30% of the GPR data set was attenuated and indiscernible data (Fig. 12), it
can be stated that a minimum of 40% and a maximum of 70% of the shallow geologic
framework could contain relict-inlet deposits.
The true value is probably closer to 70% than 40% because areas containing poor
GPR data have historically had active inlets (i.e., Buxton, Chacandepeco, Isabel, and Old
Halteras inlets). These areas are typically topographically low and vibracores indicate
that they are composed of coarse inlet-fill sediments. These characteristics likely allow
for an elevated salt water table, explaining the shallow attenuation of GPR data.
Oregon Inlet and its active flood and ebb tide deltas are the modem analog for
relict migrating complex inlets. The geomorphological features associated with Oregon
Inlet are illustrated in Figure 76. Fisher (1962) noted that flood tide deltas and flood tide
delta finger channels are commonly preserved in the estuary following inlet closure.
Relict inlet throat channels are not easily distinguishable based on modem barrier island
geomorphology. Shore-parallel GPR data demonstrate that relict inlet throat channels are
Pamlico Sound
ESTUARINE BASIN
FLOOD TIDE DELT/
FINGER CHANNEL
BoDiE Island
Pea Island
EBBTIDE D
Atlantic
Ocean Imiige G 2006 DIgitalGlobeImaae O 2006 TerraMetrIcs Gooqm
Fig. 76. Oblique aerial photo (Google Earth) showing Oregon Inlet and its flood and ebb tide deltas. The ebb tide,
inlet throat channel, flood tide delta, and finger channels are shown in green, red, blue, and yellow, respectively.
Oregon Inlet is a modern analog for relict migrating complex inlets.
154
present beneath the modem barrier in many locations. Ebb tide deltas and occasionally
throat channels are not readily preserved due to destmction by wave action along the
shoreface as the barrier islands transgress in response to rising sea level and storm
dynamics.
Figure 8 summarizes observed relict inlets in the GPR dataset from NC Highway-
12. Barrier island segments characterized by either the Overwash Radar Facies or
poor/no data may be sites of relict inlets, but inlet features are not represented in the GPR
data and so this is unknown. Additionally, the amount of transgression that has occurred
along portions of the Outer Banks since relict inlets were last active, controls what is
potentially preserved and recorded in the GPR data.
Figure 77 shows a typical barrier island transgressive sequence in regions
containing active inlets during some period of time. Island segments become more
continuous upon closure of inlets. Barrier island transgression and wave ravinement
often destroys the underlying relict inlet throat channel and ebb tide delta at the
shoreface. With time, the island perches on top of the relict flood tide delta (Fig. 77). In
cases where inlets closed centuries ago and the Outer Banks have experienced significant
transgression, the modern barrier chain is perched upon relict flood tide delta deposits
(Schwartz and Birkemeier, 2004). Therefore, channel geometries observed in GPR data
acquired along these sections of the Outer Banks may indicate flood tide delta finger
channels that are associated with the relict inlet. Evaluation of historic maps from
northeast Ocracoke Island shows that this situation exists in the area (Fig. 78).
Fig. 77. Illustration of typical barrier transgression in the area of an inlet. Panel A shows morphological features
associated with an active inlet. In Panel B the inlet has closed but relict morphological features exist in the
shoreface and estuary. The relict ebb tide delta and throat channel have been destroyed by wave action in the
shoreface of a transgressing barrier island in Panel C. Panel D shows a barrier that has experienced significant
transgression since inlet closure, migrating onto the flood tide delta.
Natteras
Inlet'^
Pamlico ” kilometers
Sound
Minimal Inlet
Shorelini Migration
Change ~1 km of
Barrier
Transgression
Ocracoke Minimal
Inlet ShorelineV
Change
j 1866 Shoreline]
Prograding H “ “ ~1866ShoalS
Spit
PlatTorm
Fig. 78. Georeferenced shoreline from the 1866 U.S. Coast Topographieal Sheet No. 792 (D. Ames, personal communication,
2006) projected on to the 1998 DOQQ (USGS) of Ocracoke Island. The solid pink line represents the location of the
shoreline in 1866 and the dashed pink line indicates shoals present in 1866. Northeast Ocracoke Island has experienced
~1 km of transgression and central Ocracoke and Ocracoke Village have experienced relatively little transgression from
1866 to 1998.
157
Migrating channel geometries in GPR data are produets of migrating inlet throat
channels. Relict throat charmels may be distinguishable from relict flood tide delta finger
channels in GPR data by channel width and depth, as well as amount of channel
migration present. The throat channel of Oregon Inlet is wider, deeper, and has migrated
further than its flood tide delta finger channels. The modem inlet throat channels at
Oregon, Hatteras, and Ocracoke Inlets do not extend more than approximately 0.5 to 1
km landward of the shoreline. In these eases where barrier island transgression is
minimal to moderate sinee closure of the channel the relict throat channel may be
preserved. Barrier segments that mateh this description include Pea Island/New Inlet,
Salvo, Kinnakeet region, Avon, and the Isabel Inlet region (between Cape Hatteras and
Hatteras Village).
Classifieation of Radar sub-facies was sometimes made difficult by poor and
incomplete GPR data. Sub-facies within the Inlet Radar Facies (Non-Migrating/Single
Inlet, Non-Migrating/Complex Inlet, and Migrating Complex Inlet) were especially
difficult to distinguish. Chaimel geometries were at times incomplete and lacked entire
sides of channels. In these cases, the measured distance of the extent of a charmel is
inaceurate.
Spatial Distribution of Inlet and Overwash Facies
Several patterns of the distribution and oceurrence of Inlet and Overwash Radar
Facies were observed in the GPR dataset from North Carolina HW-12 along the Outer
158
Banks (Fig. 8). GPR data reveal regions of the Outer Banks that are dominated by the
presence of one or more radar facies or sub-facies.
The Pea Island, southern Salvo, and Ocracoke Island regions are dominated by
Overwash Facies including both sub-facies; overwash flat/peat platform and overwash
channel (Figs. 8, 9, 10, 11). The GPR data in these regions are characterized mostly by
the overwash flat/peat platform radar sub-facies with common overwash channel
occurrence and rare non-migrating/single sub-facies. Other than rare occurrences of the
non-migrating/single sub-facies, the GPR data in these regions lack evidence of relict-
inlet geometries. The presence of active inlets nearby possibly deterred inlet formation in
the Pea Island, southern Salvo, and Ocracoke regions during high-energy storm events.
Pea Island is currently bordered by Oregon Inlet to the north and was bounded by New
Inlet to the south (Fig. 1). The southern Salvo region of the Outer Banks (Fig. 10) has
been bound by migrating complex inlets to the north (Salvo area) and the south
(Kinnakeet region). Ocracoke Island has Hatteras and Ocracoke Inlets bordering to the
northeast and southwest, respectively (Fig. 1).
The Rodanthe region is unique because it is dominated by the presence of non-
migrating inlets (single and complex) (Figs. 8, 9). This region has not historically had
active inlets, but GPR data reveal that several areas within the Rodanthe region have had
inlets one or more times. Vibracore RodIn-05-VCl was acquired at the headwaters of a
modem tidal creek in an area within the Rodanthe Non-migrating/Complex Inlet (Fig.
52). This tidal creek is likely situated in either the relict inlet throat channel or in a flood
tide delta finger channel associated with the Rodanthe Non-migrating/Complex Inlet.
159
The Salvo, Kinnakeet, Avon-Buxton, and Isabel Inlet regions are dominated by
the presence of migrating complex inlets (Figs. 8, 9, 10, and 11). Around -500-275 yrs
ago (Table 7) these migrating complex inlets were still active, but probably did not all
exist simultaneously. The Avon and Kinnakeet Complex Inlets probably did not exist
simultaneously due to their close proximity to each other. It is more conceivable that
more distant complex inlets (i.e.. Salvo Complex Inlet) coexisted with either the
Kirmakeet Complex Inlet or the Avon Complex Inlet. Migrating complex inlets
transitioned to topographically low shoals upon closure that eventually built elevation to
through storm overwash to support vegetation. The areas of the Salvo, Kirmakeet, and
Avon Complex Inlets were among the last places to become sub-aerial and complete the
configuration of the modern continuous barrier segment north of Cape Hatteras
approximately 275 years ago (Table 7).
Historical Inlets
Historical inlet activity has been documented since 1584 A.D. along the Outer
Banks. Discrepancies between locations of inlets exist in the historic records and GPR
data. The largest discrepancy exists between the temporal and spatial occurrence of
migrating complex inlets. This present study used OSL dating on channel-fill quartz
sands of several migrating complex inlets along the Outer Banks and determined that
there was a period of increased inlet activity from -500-275 yrs B.P. This period is
mostly within historic times (post 1584 A.D.). However, maps of the area created during
160
this period do not always agree with OSL ages and GPR data. There are several
explanations for this discrepancy.
Maps of the Outer Banks created during the period of increased inlet activity from
~500-275 yrs. B.P. may be variably reliable. Some earlier maps from ~500-275 yrs. B.P.
depict the Outer Banks as a continuous barrier chain with minimal inlet activity (Fig. 79)
and others show more inlets (Fig. 80), but the relative and true locations of the inlets are
unclear (Fig. 80). It was not until the late 18*’’ century that maps were drawn more
accurately (Fig. 81).
The Outer Banks were likely not targeted by early cartographers who may have
been more interested in discovering higher and drier ground for settlement (S.R. Riggs,
personal communication, 2006). In 1584 A.D., an expedition sent by Sir Walter Raleigh
chose Roanoke Island as the site for an English fort and base of operations because it was
thought that the Outer Banks would conceal the colony from Spanish ships passing by in
the ocean (Williams and Johnson, 1996). However, navigation through and around inlets
in the area was so treacherous for sixteenth century ships bringing colonists and supplies
to the colony on Roanoke Island that the ships had to be anchored off shore of the Outer
Banks and likely was a major reason for the failure of the Roanoke settlement (Williams
and Johnson, 1996). Often times new maps of the Outer Banks were just copied by
cartographers from existing maps with minor updates (S.R. Riggs, personal
communication, 2006). Even Ocracoke Inlet, which was navigable in 1584 A.D., had
shoaled to the point in 1585 A.D. where Queen Elizabeth’s flagship Tiger could not
navigate the inlet (Williams and Johnson, 1996). When inlets were drawn on historic
161
Albemarle
Sound
Pamlico V- * ^
Sound
j’; V
Unnamed Inlet Unnamed Cape Roanoke
(Ocracoke Inlet?) (Cape Natteras?) Island
Fig. 79 Map of the Outer Banks by Comberford made in 1657 A.D. (Williams and
Johnson, 1996). West is to the top of the map. A continuous barrier chain with
minimal inlets is illustrated directly north and south of the unnamed cape. The
Outer Banks is drawn with minimal detail. Roanoke Island is depicted as a nearly
circular island that is open to the ocean.
162
bemarle Sound
Roanoke Island
-Continuous/
Discontinuous
Barrier Chain
(Multiple Inlets)
Cape Hatteras
Pamlico Sound
irB,STBRlV
O C E^N
Fig. 80. Map of the Outer Banks by Lawson made in 1709 A.D. (Hawks, 1858). The
region of the Outer Banks north of Cape Hatteras to the Roanoke Island region
shows multiple inlets creating a semi-continuous to discontinuous barrier chain
Mosely 1733 Map Beilin 1764 Map Price-Strother 1808 Map
Fig. 81. Comparison of maps illustrating the Outer Banks. The 1733 map by Mosely and 1764 map by Beilin (Williams and
Johnson, 1996) are not as detailed as the Price-Strother map of 1808 (Williams and Johnson, 1996). Maps of the Outer
Banks have been drawn with more detail and accuracy since the late 18'*' century.
164
maps, the location and size of the inlets were commonly incorrectly portrayed due to
navigation limitations. Cartographers in sailing vessels likely had great difficulties
accessing inlets from both the east and west sides of the Outer Banks. Inlets (especially
ephemeral inlets) have shallow ebb - and flood- tide deltas that make navigation
challenging or impossible. The large shoals present to the west of the Outer Banks are
typically less than 1 m deep and would have been inaccessible to most sailing vessels
used in the 16'*’ and 17'*’ centuries. The maps created during this period were constructed
so infrequently (as much as 50-75 years between maps) that they only provided a
snapshot of the configuration of the Outer Banks at that specific time and likely did not
capture more ephemeral inlet activity that was likely occurring during this period.
OSL age estimates on inlet channel-fill from the Salvo and Kinnakeet Complex
Inlets returned 2-sigma ages of 553-324 yrs. B.P. and 509-341 yrs. B.P. (Table 7),
respectively. The English arrived on the Outer Banks 421 yrs. B.P. (1584 A.D.)
(Williams and Johnson, 1996). Much of the Salvo and Kinnakeet Complex Inlet age
estimates predate the arrival of the English and it is possible that these inlets were closed
or closing when the first cartographers arrived. Figure 82 shows the map drawn by John
White in 1590 A.D. six years after the arrival of the English on the Outer Banks. White’s
map accurately shows the locations of Ocracoke Inlet, Pamlico Sound, Cape Hatteras,
and Roanoke Island (Fig. 82). Multiple inlets are illustrated to the east and southeast of
the colony on Roanoke Island, but few inlets are depicted elsewhere (Fig. 82). Roanoke
Island and the regions of the Outer Banks to the east appear to generally be drawn with
greater detail than the barrier chain to the south (Fig. 82). Cartographers possibly
Pamlico CMin.
Sound"
Ocracoke^
Inlet w
Ooaioftrt.
'Hntudiii
SXIC^JW FPrtNIKK)
Cape 4
Hatterasii
ri: Ï « ««<c e'C'S-cyf£'oc«« »a *3^1 s-sx-ï-a»
Unnamed Unnamed Roanoke 'Albemarle
Fig. 82. Map from 1590 A.D. drawn by John White (Williams and Johnson, 1996) showing the Outer Banks. This map was
made five years after the establishment of the English colony on Roanoke Island. The relative locations of Pamlico
Sound, Ocracoke Inlet, Cape Hatteras, Roanoke Island, and Albemarle Sound are accurately drawn, but the spatial
distribution of inlets on the map does not agree with GPR data and OSL age estimates from the present study. An
unnamed inlet is illustrated at the location of Cape Hatteras and an unnamed cape is shown at the location of Wimble
Shoals.
166
focused mapping efforts on the areas surrounding the English settlement on Roanoke
Island. An unnamed inlet with extensive shoals extending into the Atlantic Ocean is
illustrated at the site of Cape Hatteras and Diamond Shoals (Fig. 82) and an unnamed
cape to the north of Cape Hatteras drawn at the approximate location of Wimble Shoals,
is illustrated in White’s map (Fig. 82). The barrier between the urmamed inlet and cape
shows a continuous barrier (Fig. 82) where the Salvo, Kirmakeet, and Avon Complex
Inlets would have been located. It is possible that navigational hazards created by the
shoals of the unnamed inlet to the south and the unnamed cape to the north did not permit
navigation and mapping near the Outer Banks in this region or the unnamed inlet at Cape
Hatteras is actually representing either the Salvo, Kirmakeet, or Avon Complex Inlets.
Fisher (1962) summarized the approximate location and existence of historic
inlets along the Outer Banks from historic maps. Fisher (1962) did not attempt to
estimate the size of inlets illustrated on historic maps made prior to ~250 yrs. B.P.
because these maps were generally poor and could only provide approximate locations of
inlets. GPR data do not agree with the approximate location of historical inlets according
to Fisher (1962) in some locations. The approximate location of Loggerhead Inlet (Fig.
9) (Fisher, 1962) is near non-migrating/single inlets to the north and to the south, but
does not correlate precisely with GPR data, meaning one of the inlets identified in the
GPR data is likely Loggerhead Inlet, but the approximate location derived from historic
maps is off by at least -0.5 km (Fig. 9). The approximate location of historic
Chickinaccomock Inlet (Figs. 9, 14) (Fisher, 1962) correlates with Overwash Radar
Facies and does not indicate the presence of any inlet channel. A non-migrating/complex
167
inlet ~1 km to the south (Fig. 14), a region with poor/no data ~1 km to the north (Fig. 14),
or a non-migrating/complex inlet ~1 km to the south (Fig. 14) could be the actual location
of Chickinaccommock Inlet.
Oregon Inlet
Oregon Inlet originally was opened by a hurricane on September 8, 1846 (Fisher,
1962). The same storm opened the modem Hatteras Inlet (Fisher, 1962). These inlets
serve as the modem analogs for migrating complex inlets. Oregon Inlet and Hatteras
Inlet have migrated southward ~3 km and ~2.5 km, respectively.
Figure 83 shows the positions of the 1998, 1962, 1932, and 1849 shorelines and
the location of vibracores OreIn-06-VCl and OreIn-06-VC2. The historic shorelines
show patterns of barrier erosion and accretion, inlet migration, inlet closure, and inlet
reincision (Fig. 83). At the site of the vibracores, the shoreline at Oregon Inlet eroded
-0.75 km from 1849-1962. From 1962-1998, the shoreline has accreted -0.35 km.
The location of the vibracores is -1 km west of the location of the 1849 Oregon
Inlet throat channel (Fig. 83). When the inlet was active at this location in 1849, flood
tide delta sands were deposited at the location of the vibracores. The inlet migrated
southward -1.1 km between 1849 and 1932 resulting in the deposition of prograding spit
platform sands in the area of the vibracores (Fig. 83). During the Ash Wednesday storm
of 1962, the inlet eroded out much of the prograding spit platform -1 km south of the
location of the vibracores (Fig. 83). During the 1962 storm, the location of the
vibracores was on the reduced spit platform and dominated by overwash sands. Since
168
1962, Oregon Inlet has migrated south ~2.5 km to its modern location (Fig. 83). Figure
84 illustrates the sequential stratigraphic deposition of sediments at the location of the
vibracores since 1849.
Two OSL samples from Oregon Inlet were utilized as proof of concept samples to
confirm the use of OSL dating on inlet-fill sands. Both samples were taken from
vibracore OreIn-06-VCl from lithologic units of known age. The shallower sample from
2.98-3.16 m depth below surface returned an age of 124 ± 21 yrs. B.P. and the deeper
sample from 3.16-3.41 m below surface returned an age of 170 ± 29 yrs. B.P. (Table 7).
The OSL age of the shallower sample ranges from 145-103 yrs. B.P. (1861-1903 A.D.)
indicating the sands sampled were either deposited as flood tide delta sands associated
with the 1849 Oregon Inlet or prograding spit platform sands towards the end of the 19'*’
century.
The OSL age of the deeper sample ranges from 199-141 yrs. B.P. (1807-1865
A.D.) indicating the sands were deposited in similar environments as the shallower
sample. The age range of this sample can be narrowed by the known date of opening.
The actual age range of this sample is 1846-1865 A.D. The age ranges of the two
samples overlap for the years from 1861-1865 A.D. and can be interpreted as being
deposited during the same shoaling event during the progradation of the spit platform at
that time. These samples confirm the use of OSL analysis to obtain age estimates for
marine sands deposited within inlet throats and in marine environments adjacent to inlets.
169
1849 Coastline
1932 Coastline
1962 Coastline
Oreln-06-VC1
and 1849 Inlet Throat
Oreln-06-VC2
Atlantic
Pamlico
Sound
kilometers
1998 Inlet Throat k
Fig. 83. A 1998 DOQQ (USGS) shows the progradation of the northern spit platform
associated with Oregon Inlet through time. Shorelines traced from geo-referenced
topographic survey charts and are projected onto the 1998 DOQQ to show the
complex evolution of this spit platform. The location of vibracores OreIn-06-
VCl and OreIn-06-VC2 are represented by the black star.
170
I -10 M 1
ORElN-Oe-VCl OREIN-06-VC2
I MODERN SURFACE [
POST 1962 OVERWASH SANDS
ASH WEDNESDAY STORM
OVERWASH DEPOSIT
1962A.D.
PROGRADING SPIT
PLATFORM DEPOSIT
OSLAGE
CA. 1849-1932A.D. RANGE
ESTIMATES
1 1861-1903 A.D.
FLOOD TIDE ^\1807-1865 A.D.
DELTA DEPOSIT
CA. 1849A.D.
Fig. 84. Core logs show the stratigraphy and the depositional interpretation at the
location of vibracores OreIn-06-VCl and Oreln-06-VC2 (Fig. 83). Figure 83
illustrates the locations of historic shorelines at the site of the Oregon Inlet
vibracores. The location of the Oregon Inlet throat channel has changed position
continuously through time since 1849 A.D. resulting in the deposition of the
sequences illustrated above.
171
Pea Island: S-Curves Region
Smith (2004) evaluated historic aerial photos from the past 150 years and
determined that ocean shoreline erosion and overwash were the main environmental
changes to occur in the Pea Island: S-Curves region during this period. GPR data from
this region agree with Smith’s conclusions and demonstrate that the region has been
dominated by overwash (Fig. 9). Vibracore ChicIn-05-Sl was acquired at the site of two
3-D GPR surveys (Fig. 14). Figure 85 shows the location of the vibracore on a 2003
DOQQ taken after Hurricane Isabel. The site of the vibracore was inundated by
overwash from the Hurricane Isabel storm surge as the artificial barrier dune ridge was
breached.
The recent surficial overwash sediments are underlain by a sandy peat horizon in
the vibracore creating a typical sequence indicative of overwash (Fig. 86). The presence
of a peat horizon at the site of ChicIn-05-Sl (Fig. 85) indicates that the area has likely not
been incised by inlet channels since the peat began to grow. Smith (2004) dated two peat
horizons (depths of 18.5 and 74 cm below MSL) in vibracores ~ 0.5 km north of
vibracore ChicIn-05-Sl. The shallow peat returned a date range of 282-168 calibrated
yrs. B.P. and the deeper peat was dated from 962-662 calibrated yrs. B.P. (Smith, 2004).
Since the peat from vibracore ChicIn-05-Sl was not dated, two possible hypotheses exist
regarding the age of the peat in ChicIn-05-S 1. If the peat horizon encountered in Chicin-
05-Sl from this study (Figs. 85, 86) is of similar age to the shallower peat dated by Smith
(2004), then it can be said that this region has lacked inlet activity for almost three
Fig. 85. A 2003 DOQQ (USGS) shows the Pea Island; S-Curves region following Hurricane Isabel. The site of vibracore
ChicIn-05-S 1 is shown (red dot). The artificial barrier dune ridge was flattened allowing extensive overwash over NC
Highway-12 and onto the back-barrier. The northern Pea Island: S-Curves region is a future potential inlet site.
173
Core
LF Log G.P.R Rl.
: ?>
9^(rtd) Overwash
r.;
Salt
sP Marsh
1 •'
1
^(rtd) 1* •
9®(gr)
rupia» Estuarine
Shoal
gs/
Q. ^(lam) • • • *>—• - -• •f «?i
(D
Û "•ip" K •rtPl
r.\’-
gS/ -j" ^ b-‘ -i'
^(lam) » 11 Estuarine
I Z " ? »
* Shoal
1^
• V
gS/ • - .
^(lam) Ill 1II
?I.,,
1
i
Chicln-05-S1
Fig. 86. This figure illustrates the Radar-Litho-Bio-Facies (RLBF),
lithofacies (LF), lithofacies illustration (legend in Fig. 54), GPR data
adjacent to vibracore and paleoenvironmental interpretations (PI) for vibracore
ChicIn-05-Sl. Pis were made solely on supplemental data.
174
centuries. If the peat horizon encountered in ChicIn-05-S 1 is of similar age to the deeper
peat dated by Smith (2004), then it can be said that the area adjacent to ChicIn-05-Sl
(Fig. 85) has lacked inlet activity for at least 662 years and as much as 962 years.
The site of vibracore ChicIn-05-Sl (Fig. 85) at the Pea Island: S-Curves region
has existed as a sub-aerial environment without inlet activity for at least the last ~300
years and as much as the last ~950 years based on age estimates of two peats acquired in
vibracores from Smith (2004) taken ~0.5 km north of ChicIn-05-Sl. GPR and lithologic
data indicate that this area has been dominated by overwash processes associated with
barrier transgression in response to rising sea level. This region does not appear to have
been incised by inlets since the area became sub-aerial. However, anthropogenic
influences such as the artificially constructed barrier dune ridges have deprived the back-
side of the barrier of sediment from overwash processes. Thus the Pea Island; S-Curves
region of the Outer Banks is exceptionally narrow (Fig. 85) and a likely location for
future inlet activity.
Rodanthe Non-Migrating/Complex Inlet
The to-wn of Rodanthe generally consists of a wider section of the Outer Banks
that is currently not as threatened by inlet formation as narrower regions of the Outer
Banks. During Hurricane Isabel (September 2003), the town experienced widespread
overwash from the storm surge that flattened an artificial barrier dune ridge constructed
175
adjacent to the shoreface, deposited vast amounts of sediment towards the back-barrier
side of the island, and flooded tidal creeks on the west side of the island.
The extent of the Isabel overwash is evident in the 2003 DOQQ taken
immediately following the hurricane (Fig. 87) and in vibracore sediments where -0.6 m
of overwash sand were encountered on top of granite gravel that likely was from an old
parking lot (Fig. 88). Vibracore RodIn-05-VCl is at the headwaters of a tidal creek that
experienced significant flooding during Isabel (Fig. 87). Historieally, the town of
Rodanthe has experienced overwash and overwash ehannels, but inlets have not been
reported.
GPR data within the town of Rodanthe indicate the presence of a non-
migrating/complex inlet approximately 0.75 km wide (Fig. 52). A meandering tidal
creek on the back-side of the barrier (Fig. 87) is the only modem géomorphologie feature
in Rodanthe that is associated with the inlet identified in the GPR data (Fig. 53). Rodin-
05-VCl was taken in a hotel parking lot at the headwaters of this tidal creek (Fig. 87).
Overwash sands from Hurricane Isabel in 2003 are underlain by a sandy peat horizon
(Fig. 88) that appears to mimic the shape of the underlying channel geometry. This
indicates that the peat horizon grew in a pre-existing, topographically low back-barrier
channel. An OSL date directly beneath the peat, in sediments interpreted to be on an
estuarine shoal, returned an age of 305 ± 28 yrs. B.P. indicating that the peat formed after
this date. Sediments deposited in the lower portion of the vibracore and during the
closing stages of the Rodanthe Non-Migrating/Complex Inlet occur beneath the
sediments dated with OSL (Fig. 88).
75°28'0"W
35°35'0''N
Fig. 87. A 2003 DOQQ shows the town of Rodanthe following Hurricane Isabel. The location of vibracore Rodln-05-VCl
(green dot) is shown. The storm surge produced extensive overwash and flooding of tidal creeks. Approximately 0.6
m of sediment was deposited during this event at the site of Rodln-05-VCl from the overwash event.
177
Core
O LF _Loa. G.P.R P.I.
^(shelly)
2(rtd)
^^(shelly)
sP
9®(shelly)
^(rtd) 333-277
yrs.B.R
^^(bur)
Q.
0)
Q 9®(shelly)
^(shelly) 876-696
yrs. B.R
^(mas)
Rodln-05-VC1
Fig. 88. This figure illustrates the Radar-Litho-Bio-Facies (RLBF), lithofacies (LF),
lithofacies illustration (lithofacies legend in Fig. 51), GPR data adjacent to
vibracore, paleoenvironmental interpretations (PI), and age analyses for vibracore
Rodln-05-VCl are shown. Two OSL ages are shown.
178
Downcore lithologic variations in inlet-fill sediments reflect fluctuations in
energy experienced by changes in inlet activity in the Rodanthe Non-Migrating/Complex
Inlet. This inlet occupied and reincised this region multiple times. The deepest inlet
sediments occur ~3.5 to 4 m beneath the surface and are interpreted to have been
deposited in an inlet channel near the inlet throat (Fig. 88). The deepest inlet sediments
are overlain by coarser shelly gravelly sands likely deposited within the inlet throat
channel (Fig. 88). The coarser, shallower inlet sediments were likely deposited as the
barrier chain transgressed westward bringing the inlet throat closer to the site of vibracore
RodIn-05-VCl. Overlying the shallower inlet-fill is a burrowed muddy sand unit
interpreted as a flood tide delta deposit (Fig. 88). The burrowed muddy sand unit was
likely deposited during a period when the Rodanthe Non-Migrating/Complex Inlet was
closed creating a much less energetic environment that allowed for deposition of mud.
An OSL age estimate of 876 to 696 yrs. B.P. was returned on inlet-fill sands ~3.5
m below surface from the Rodanthe Non-Migrating/Complex Inlet. This age indicates
that the inlet was active earlier than the Salvo, Kinnakeet, and Avon Complex Inlets
(-550-275 yrs. B.P. (Table 7)). The Rodanthe inlet has not been active since at least 305
± 28 yrs. B.P. as indicated by the shallower OSL age (Fig. 88).
Salvo Complex Inlet
The Salvo region (town of Salvo and Salvo Day Use Area) has experienced
extensive inlet activity during the late Holocene. Two migrating complex inlets in the
179
Salvo region were identified (Fig. 54) with GPR (Fig. 55). One complex inlet is within
the town of Salvo and one underlies the Salvo Day Use area (Salvo Complex Inlet) (Fig.
54).
The Salvo Complex Inlet extends ~1.75 km south from the town of Salvo to the
southern extent of the Salvo Day Use Area (Fig. 54). GPR data reveal the final position
of the inlet throat channel occurred at the southernmost -0.25 km of the complex inlet
after the active charmel migrated -1.5 km to the south (Fig. 55). OSL analyses of inlet-
fill sediments from vibracores within the Salvo Complex Inlet returned an age range
estimate of 553 - 324 yrs. B.P. (Table 7) meaning the Salvo Complex Inlet was active
-450 years ago. GPR surveys at the location of the Salvo Complex Inlet show that upon
closure, the area remained as a topographically low, likely unvegetated, and overwash
prone area that was incised multiple times by overwash channels during storm events
(Fig. 20). No back-barrier peat platform has been able to establish at the location of the
Salvo Complex Inlet since closure, but a salt marsh does exist in the southern Salvo Day
Use area outside the southern extent of the Salvo Complex Inlet.
Another migrating complex inlet was identified to the north of the Salvo Complex
Inlet and is entirely within the town of Salvo (Fig. 54). This complex inlet is separated
from the Salvo Complex Inlet to the south by - 1 km of overwash radar facies (Fig. 54).
GPR data reveal a high-amplitude continuous horizontal to sub-horizontal reflection at -2
m below the surface that is characteristic of a peat horizon (Fig. 55). This overwash-
dominated area likely remained as a sub-aerial landform during the existence of one or
both of the adjacent complex inlets. Vibracore SalIn-05-VC2 was taken within the
180
northern Salvo complex inlet (Fig, 57). An OSL age on inlet-fill sediments returned an
age range of 525 to 421 yrs. B.P. (Table 7), meaning this inlet was active -475 years ago.
This age indicates that the northern Salvo complex inlet could have co-existed with the
Salvo Complex Inlet to the south. Further research on the overwash-dominated region
between the two inlets is needed to determine if they co-existed as one larger complex
inlet or individually, and separated by a sub-aerial barrier segment. Both complex inlets
in the Salvo region could have co-existed with the Avon and Kinnakeet Complex Inlets
further to the south according to OSL age estimates and GPR data.
Vibracores SalIn-05-VCl and SalIn-05-VClB were acquired adjacent to the
southern extent of the Salvo Complex Inlet to aid in interpreting paleoenvironmental
change in the Salvo region prior to the existence of the two complex inlets (Fig. 54).
Lithologic units in the two cores (acquired < 1 m apart) are similar, but have varying
thicknesses (Fig. 89). A massive sand unit at -5 m depth below the surface in vibracore
SalIn-05-VCl returned an OSL age estimate of 2163 to 1875 yrs. B.P. and is interpreted
to be an inlet channel deposit. Ricardo (2005) interpreted a similar unit at similar depths
~2 km to the south to be an open marine deposit. The southern Salvo Day Use area is
characterized by a comparable stratigraphic record as that described by Ricardo.
Considering environmental conditions described by Ricardo (2005) at 2163 to 1875 yrs.
B.P., an inlet could not have existed at the location of SalIn-05-VCl since sub-aerial
islands did not exist on the barrier segment to the south. Therefore, the sediments dated
with OSL in vibracore SalIn-05-VCl were likely deposited as a sub-tidal shoal that
allowed open marine circulation in central Pamlico Sound.
Core Core
RLBF LF Age P.l. Age
Back-
—
barrier/
S(rtd) S(rtd) overwash
— Salt
sP marsh
®(rtcl) 1 - sM(rtd)
^<ifm(rtd)®(bur;rtd) as)l SaltsP ^1-221marsh “
®(mas) '^S(rtd) Estuarine cal. yrs. B.P.
— Shoal
S(bjr)
— S(rtd) Estuarine— S(bur) Shoal
_ S(bur)
®(mas) 676-524
^(mas) B.P. 2{lam)yrs.
— M/S E -
^''^(bur) M/S
—
?B 1526-1356
Cl Q. ®’^(bur) cal.— yrs. B.P.
(Ü 'r®(bur) 0)
Q __ ^(mas) Q — '^^(bur)
_ M/S — ®(mas)
M'*'(,mas)
M/S
_
—
'^^(bur)
— 3-c S(mas) 2163-1875 5 :
— ®(8helly) ^(mas)yrs. B.P. ^(shelly)
—
"^^ishelly)
—
Salln-05-VC1 Salln-05-VC1B
Fig. 89. This figure illustrates the Radar-Litho-Bio-Facies (RLBF), lithofacies (LF) (lithofacies legend in Fig. 51), GPR data
adjacent to vibracore, paleoenvironmental interpretations (PI), and age analyses for vibracores Salln-05-VCl and
Salln-05-VClB. Pis in black were not assigned an RLBF value and were made solely on supplemental data. Pis in
red were assigned a RLBF value based on GPR, lithologic, and foraminiferal characteristics. Two OSL ages are shown
in black and two radiocarbon ages are shown in blue.
182
A barrier island must have formed in the southern Salvo Day Use area at the
location ofvibracores SalIn-05-VCl and SalIn-05-VClB (Fig. 54) after 1875 yrs. B.P
according to age estimates from the two additional vibracores. An articulated in situ
Chione cancellata bivalve from vibracore SalIn-05-VClB (Figs. 54, 55) within a
burrowed sandy mud at ~3 m below surface returned a radiocarbon age range from 1526
to 1356 calibrated yrs. B.P. These data suggest a barrier island formed at the location of
vibracores SalIn-05-VCl and SalIn-05-VClB in the southern Salvo Day Use area after
1526 to 1356 yrs. B.P. This generally correlates with the paleoenvironmental
interpretations made by Ricardo (2005) for Pamlico Sound in the south Salvo region.
Ricardo (2005) interpreted Pamlico Sound to be a restricted embayment begirming -1250
yrs. B.P. where barrier islands and active inlets existed creating restricted marine
circulation in the south Salvo region of Pamlico Sound. The present study finds that a
barrier must have existed in the southern Salvo Day Use area -2 km north of Ricardo’s
study area by 1526 to 1356 calibrated yrs. B.P. At some point between 2163 to 1875 yrs.
B.P. and 1526 to 1356 calibrated yrs. B.P. a sub-aerial barrier island formed to the east of
the location of the two vibracores.
An OSL sample at -2.3 m depth below surface in vibracore SalIn-05-VCl (Fig.
54) on sediment interpreted as an estuarine shoal deposit returned an age range of 676 to
524 yrs. B.P (Fig. 89). The OSL age estimate on the estuarine shoal deposit does
generally correlate with the period when the Salvo Complex Inlet was active (-500 yrs.
B.P.) indicating that this sample could be a flood tide delta deposit.
183
A salt marsh peat accumulated above the low energy sands (Fig. 89) in vibracore
SalIn-05-VClB. The radiocarbon age of this peat ranges from 291 to 221 calibrated yrs.
B.P. (Fig. 89). By this time, adjacent inlets had closed and an environment similar to the
present day environment had been established. Ricardo (2005) demonstrated that salt
marshes on the modem barrier in the south Salvo region began forming approximately
220 to 140 calibrated yrs. B.P. and the marshes on Gull Island were established
approximately 540 to 460 calibrated yrs. B.P. The marshes of the modem barrier in the
south Salvo region started accumulating at about the same time (~220 to 140 calibrated
yrs. B.P.) as the marshes in the Salvo Day Use area ~2 km to the north (-291-221
calibrated yrs. B.P. This indicates that the Salvo Day Use area began to stabilize via
marsh accretion at the same time as the south Salvo region.
In the Salvo region, sub-aqueous geomorphic features (Wimble Shoals) occur in
the nearshore ocean environment. Wimble Shoals are a series of sub-aqueous ridges
consisting of resistant Pleistocene deposits that trend northeast/southwest at -25° to 30°
angles to the modem barrier (Riggs et al., 1995) (Fig. 90). These features could have
influenced barrier evolution and inlet activity in the Salvo region by refracting waves and
redistributing energy upon the shoreface.
Kinnakeet Complex Inlet
Figure 60 shows the location of the Kinnakeet Complex Inlet and the Kinnakeet
region. Inlets have not been recorded in the Kinnakeet region during historic times (post-
184
2 Km
rkr
27
Salvo X 4S
Complex
Inlet -e M
Atlantic
, Ocean
Fig. 90. Shallow bathymetric data are presented in blue for Pamlico Sound and Atlantic
Ocean areas adjacent to the Salvo region. Wimble Shoals are evident in the
nearshore environment and likely have influenced the barrier evolution of this
region by refracting waves and redistributing energy upon the shoreface. Depths
are in meters.
185
1584 A.D.), but GPR data reveal the subsurface is dominated by the presence of multiple
migrating complex inlets (Figs. 60, 61).
The Kinnakeet Complex Inlet underlies approximately a 1.8 km stretch of the
Outer Banks south of the Salvo region and north of the Avon region (Fig. 10). OSL ages
on inlet-fill sediments show the Kinnakeet Complex Inlet was active at least two times
(-1200 yrs. B.P. and -400 yrs. B.P. (Table 7) (Fig. 91). GPR data at the location of
vibracore KirmIn-05-VC2 (Figs. 60) show two high amplitude dipping clinoforms
indicative of inlet sediment fill (Fig. 91). Two OSL samples from vibracore KinnIn-05-
VC2 targeted the two high amplitude reflections seen in GPR data at -2.2 m and -1.5 m
below the surface (Fig. 91) and returned age ranges of 1312 to 1072 yrs. B.P. and 458 to
362 yrs. B.P., respectively (Fig. 91). Two OSL samples were taken from Kinnln-05-VCl
(Fig. 91) at the southern edge of the complex inlet (Fig. 60). The deeper sample from
KinnIn-05-VCl (-2.4 m below the surface) ranged in age from 509 to 397 yrs. B.P. (Fig.
91) and the shallower sample (-1.7 m below the surface) returned an age range of 399 to
359 yrs. B.P. (Fig. 91). These ages agree stratigraphically, and therefore were deposited
sequentially. Since OSL age range estimates from the north (458 to 362 yrs. B.P. (Table
7)) and south (509-359 yrs. B.P. (Table 7)) edges of the Kinnakeet Complex Inlet overlap
and suggest a temporal existence for the complex inlet between 509 to 359 yrs. B.P.
Vibracore KinnIn-05-Sl was acquired at the extreme north edge of the Kinnakeet
Complex Inlet adjacent to the location of a 3-D GPR survey (Fig. 21) that revealed linear
features interpreted as recurved spits (Fig. 24). GPR data suggest that KirmIn-05-Sl
likely was the northernmost extent of the most recent segment of this complex inlet (Fig.
Core Core
Fig. 91. This figure illustrates the Radar-Litho-Bio-Facies (RLBF), lithofacies (LF) (lithofacies legend in Fig. 51), GPR data
adjacent to vibracore, paleoenvironmental interpretations (PI), and age analyses for vibracores Kinnln-05-VCl and
Kinnln-05-VC2 are shown. Pis in black were not assigned an RLBF value and were made solely on supplemental data.
Pis in red were assigned an RLBF value based on lithologic, foraminiferal, GPR data. Four OSL ages are shown.
187
21). OSL analysis on inlet-fill sediments in this core produced an estimated age range of
383 to 341 yrs. B.P. (Fig. 92). This age agrees with OSL ages from the other two cores
within the inlet. A burrowed muddy sand unit, interpreted as a flood tide delta deposit,
occurs at ~3 m depth below the surface and represents the lithology that the Kirmakeet
Complex Inlet incised into. The burrowed muddy sand unit was deposited to the west of
a barrier island either before the earlier period of inlet activity (-1200 yrs. B.P. (Table 7))
or during the time between the two periods of inlet activity (-1200 yrs. B.P. to -400 yrs.
B.P. (Table 7)).
Figure 93 shows relict recurved spits on the modern barrier apparent in LIDAR
data associated with the northern edge of an inlet. Recurved spits from the southern edge
of this inlet either were not preserved or exhibit no topographic expression on the modern
surface. The spit features do not correlate with the location of the Kirmakeet Complex
Inlet, but do correlate with another complex inlet directly to the south within the
Kirmakeet region (Fig. 93). No relict géomorphologie features associated with the
Kirmakeet Complex Inlet are present on the modern barrier surface, due to the presence
of the younger complex inlet to the south (Fig. 93). It can be estimated that the complex
inlet to the south of the Kirmakeet Complex Inlet was active after -400 yrs. B.P. (Table
7) by age dating and géomorphologie restrictions (i.e., the relict recurved spits). Historic
maps became more reliable and accurate -200 yrs. B.P. (-1800 A.D.) (Fig. 81). Maps
created after this time do not illustrate the presence of any inlet activity in the region
(Fisher, 1962). Therefore, it can be estimated that the complex inlet was active at some
time between -400 to -200 yrs. B.P.
188
Core
0 Age
4'
?
^(shelly) Dverwash
?.J
^^(shellv )verwash
^(lam)
Q.
0)
Q
’^(shelly Inlet
^(lam)
— i
iftll ? '
®®(shelly)
ri?¥ctt" 383-341
^(lam) Inletl/ I ' yrs. B.R
Flood
4-cl '^^(bur; Tide
Delta
Kinnln-05-S1
Fig. 92. This figure illustrates Radar-Litho-Bio-Facies (RLBF), lithofacies (LF)
(lithofacies legend in Fig. 51), GPR data adjacent to vibracore,
paleoenvironmental interpretations (PI), and age analyses for vibracore Kinnin-
05-S1. Pis in black were not assigned an RLBF value and were made solely on
supplemental data. Pis in red were assigned RLBF values based on lithologic,
foraminiferal, and GPR data. An OSL age is shown.
Barrier
NC Highway-12
Dune Ridges
Kinnakeet
Complex
In
Pamlico
Sound ^VCI Radar Sub-facies
H NSionng-lMe iIgnrlaetting/
?CNoomn-pMleigxraIntilnegt /
?CMoigmraptlienxg Inlet
?OPevaetrwPalasthfoFrmlat/
?Ove
Spits Cha
rnwnaesl h
?Poor/No Data
lActive Inlet
— Kilometers
0.4 0.8
Fig. 93. Color contour image based upon LIDAR survey data (www.NCfloodmaps.com) and displays the linear barrier dune
ridges (in red and gray colors), NC Highway-12 (in blue color), and the recurved inlet spits (in yellow and green
eolors). Recurved spits, coineiding with the northern edge of an inlet, are apparent as ridges and swales on the modern
surface south and west of vibracore Kinnln-05-VCl (black dot) and the Kinnakeet Complex Inlet. Radar facies in the
vicinity are represented by colored bloeks paralleling the Outer Banks.
190
Géomorphologie features are present on Hatteras Flats in the Pamlico Sound and
the nearshore environment on the inner shelf that could be attributed to the presence of
active inlets in the Kinnakeet region. Charmels oriented east-west on Hatteras Flats are
apparent in bathymetric data adjacent to the Kiimakeet region (Fig. 94). These charmels
can be interpreted as flood tide delta charmels associated with relict inlet activity.
Kinnakeet Shoals (Fig. 94) are a series of linear ridges that occur on the ocean shoreface
and are similar in orientation and lithology (Riggs et ah, 1995) to Wimble Shoals (Fig.
90). These shoals have likely influenced the evolution of the barrier and subsequent inlet
activity in the Kirmakeet region by refracting ocean waves and redistributing energy upon
the shoreface.
Avon Complex Inlet
The Avon region (town of Avon and adjacent area to the south) is dominated by
the presence of multiple migrating relict complex inlets (Fig. 10). Avon is a slightly
wider (~1 to 1.4 km) section of the Outer Banks. The modern geomorphology of the
region does not contain any features characteristic of relict inlets, but multiple shore-
perpendicular sub-tidal charmels are present on Hatteras Flats to the west of the Avon
region (Fig. 94). The mechanism responsible for creating these charmels is unclear, but
the abundance of relict inlets and relict flood tide deltas underlying the Avon region
could indicate that the charmels on Hatteras Flats are remnant flood tide delta finger
charmels similar to those seen on the modem flood tide delta at Oregon Inlet (Fig. 76).
Kinnakee
Region Kinnakeet
?ÜHuh On Pamlico Complex• Inlet
Sound
Kinnakeet
Shoals
ATLANTIC
Ocean
F+AVON
Avon! Complex
[ Inlet
Kilometers
0 1.25 2.5 5
Fig. 94. Modern bathymetric data (http://www.ngdc.noaa.gov/mgg/coastal/coastal.htmn are illustrated for Pamlico Sound and
Atlantic Ocean adjacent to the Kinnakeet and Avon barrier island regions (shaded black). Kinnakeet Shoals are evident
in the nearshore ocean environment and numerous channels (in yellow colors) occur on Flatteras Flats (in red colors).
These back-barrier channel features are interpreted to be the result of extensive inlet activity in the regions.
192
The flood tide delta finger channels associated with Oregon Inlet extend ~6 km westward
of the inlet throat (Fig, 76). The Harteras Flat channels in the Avon region are ~l-3 km
west of the inlet throat. Thus, it is conceivable that the Harteras Flat channels are
associated with the flood tide delta of the Avon Complex Inlet.
The Avon Complex Inlet spans a distance of ~2.7 km and underlies the town of
Avon (Fig. 64). The inlet is bordered by an overwash-dominated area to the north and
areas of no/poor data and a separate complex inlet to the south (Fig. 64). Three OSL
samples from the north and south edges of the complex inlet returned similar ages
indicating the inlet was active at a time from ~450 to 350 yrs. B.P. Two of these ages
were from sediments analyzed in vibracore AvonIn-05-VC3 on the north edge of the
complex inlet (Fig. 63). These samples were from 1.60 to 1.45 m and 2.56 to 2.41 m
below surface, respectively (Fig. 95). The age estimates from these samples overlap for
the years 387 to 352 yrs. B.P. (Fig. 95) indicating they could have accumulated during
the same depositional event. The third sample was from a depth of 2.10 to 1.95 m below
surface (Fig. 95) in vibracore AvonIn-05-VC2 on the southern edge of the Avon
Complex Inlet (Fig. 60). The overlapping range of the two samples from the northern
edge of the Avon Complex Inlet is completely within the range of the sample from the
southern edge (428-338 yrs. B.P.) (Fig. 95). Therefore, it can be estimated that the entire
Avon Complex Inlet was active at some time between 428-338 yrs. B.P. (Table 7) (Fig.
95).
Core Core
RLBF LF Log G.P.R Rl, Age
c
'^(shelly;
c*
^(shelly)
448-352
Q. A»tw»y) yrs. B.R
0)
Û
^^(shelly)
^8-338
yrs. B.R *°(«helly)
*^{shefly
^7-273
yrs. B.R
Avonln-05-VC2 Avonln-05-VC3
Fig. 95. This figure illustrates Radar-Litho-Bio-Facies (RLBF), lithofacies (LF), (lithofacies legend in Fig. 51), GPR data
adjacent to vibracore, paleoenvironmental interpretations (PI), and age analyses for vibracores Avonln-05-VC2 and
Avonln-05-VC3. Pis in black were not assigned an RLBF value and were made solely on supplemental data. Three
OSL ages are shown in black.
194
Isabel Inlet
Isabel Inlet formed in the Outer Banks during Hurricane Isabel in September 2003
(Fig. 34). GPR data and historical records indicate the Isabel Inlet region (section of the
Outer Banks between Hatteras Village and Frisco) (Fig. 33) has been dominated by inlet
activity during the Late Holocene.
Fisher (1967) speculated that relict beach ridges on Hatteras Village at one time
connected with beach ridges on Cape Hatteras. The continuous ridges were likely
dissected by storm activity creating “hurricane sluiceways” that exist today as shore
perpendicular sub-tidal estuarine bars in Sandy Bay to the west of the modem Isabel Inlet
region (Fisher, 1967). Figure 96 illustrates Fisher’s hypothesis for the evolution of
géomorphologie features in the Isabel Inlet region.
GPR data in the Isabel Inlet region were sometimes attenuated at shallow depths,
but each of the three types of inlets were identified (Fig. 33). GPR data characteristic of
migrating complex inlets were encountered in the region (Fig. 33) indicating that inlets
opened and migrated significant distances, closed, and reincised multiple times in the
same area. The orientation and narrow nature of the barrier island in the Isabel Inlet
region and the large fetch of Pamlico Sound to the west (Fig. 1) probably make this area
especially prone to inlet activity and also minimize the potential of continuous beach
ridge formation. Isabel Inlet is classified as a non-migrating/complex inlet indicating that
the inlet has incised multiple times in the same area. GPR data and historical records
195
Fig. 96. Illustration explains Fisher’s 1967 hypothesis for the evolution of the Hatteras
and Buxton beach ridges. The ridges prograded south from Buxton Woods and
were later breached (likely during a large storm), creating “hurricane sluiceways”
that exist today as shore-perpendicular estuarine shoals to the west of the modem
ridge in the Isabel Inlet region (from Fisher, 1967).
196
(S.R. Riggs, personal communication, 2006) confirm that this area has been incised
multiple times.
Twamley et al. (2006) investigated the Isabel Inlet region. Harteras Village, and
the adjacent Clam Shoals using geophysical, lithological, and foraminiferal techniques.
Basal peats from the marshes of Harteras Village were radiocarbon dated and indicate
that extensive marsh accretion occurred on Harteras Village and the Isabel Inlet region
commencing 500 to 250 yrs. B.P. (Twamley et al, 2006; Twamley, 2006). These dates
agree with the chronologic development of the Outer Banks south of Cape Harteras
produced in other paleoenvironmental studies (Grand Pre, 2005; Rosenberger, 2006;
Culver et al., in prep.) for the past ~500 years. Following the growth of the barrier in the
Isabel Inlet region, ephemeral non-migrating inlets (i.e., Isabel Inlet, 2003) have been the
dominant inlet type in the region.
Ocracoke Island
Ocracoke Island differs from the rest of the Outer Banks in that it is bordered by
two active inlets. Harteras Inlet to the northeast and Ocracoke Inlet to the southwest (Fig.
36). Harteras Inlet was opened during a major hurricane in 1846 (Fisher, 1962) and has
migrated to ~2.5 km south to its current location depositing a prograding spit platform on
the southern end of Harteras Village. In addition to Harteras Inlet, Ocracoke Island has
experienced multiple historically documented inlets including Old Harteras, Wells Creek,
Shingle Creek, and Old Nye Inlets (Fisher, 1962; G. Ballance, personal communication.
197
2006). Conflicting opinions exist on the location and timing of these inlets exist (Table
1) (Figs. 11, 36). Ocracoke Inlet has remained open in the same location since records
began in 1584 A.D. (Fisher, 1962) and likely has been in existence since the inception of
the present Outer Banks.
The location of Ocracoke Inlet is likely controlled by the presence of the
underlying paleo-Pamlico Creek late Pleistocene drainage charmel (Riggs and Ames,
2003; Mallinson et al, in review). This paleo-drainage is oriented northeast-southwest
at the western end of Ocracoke Village (Fig. 3) (Mallinson et al, in review).
The back-barrier marshes of central Ocracoke Island have a “molar tooth” pattern (Fig.
97) similar to those of Portsmouth Island, on the opposite side of Ocracoke Inlet to the
south. Studies on Portsmouth Island have determined that molar tooth morphologies are
likely the result of high energy storm events overwashing the island (Riggs and Ames, in
press-, Rosenberger, 2006). Hurricane Katrina produced nearly parallel overwash
charmels separated by overwash fans creating depositional patterns similar to molar tooth
morphologies on Dauphin Island, Alabama in August, 2005 (Fig. 98). The tidal creeks
and molar tooth marsh platform shapes on central Ocracoke Island could be the result of
a high energy event similar to the one experienced on Dauphin Island during Hurricane
Katrina in 2005. The molar tooth morphology is encountered mainly on the back-barrier
of central Ocracoke Island (Fig. 97). The central section of Ocracoke Island to the
Ocracoke Village area have remained relatively in the same locations and maintained
similar morphologies since 1894 A.D. (Fig. 78). The region separating Ocracoke Village
from central Ocracoke Island is a narrow section of island with a large shoal deposit to
TS'jJffW T5-523D-W ÍS-STITW ;5-Sr»"A' TS’SI'ffW ;£•»»?«
Fig. 97. Color contour image based upon LIDAR survey data (www.NCfloodmaps.com) and displays the geomorphic features
of Ocracoke Island. Recurved spits coincide with the southern edge of an inlet and are apparent as ridges and swales
on the modern surface at the southern Pony Pasture area. A possible dune ridge on the northern edge of the Pony
Pasture area is apparent as a shore-perpendicular ridge. Molar tooth morphologies characteristic of central Ocracoke
are indicated. Locations of vibracores in the Pony Pasture area are shown (black dots).
199
Fig. 98. Aerial photographs of Dauphin Island, Alabama (USGS photos). The top
photo was taken on September 17, 2004 immediately after Hurricane Ivan. The
bottom photo was taken on August 31,2005, two days after Hurricane Katrina.
Note the oil platform that washed ashore in the lower left corner. The yellow
arrows are reference points for before and after comparison. These storms formed
morphologies similar to those of central Ocracoke Island and Portsmouth Island
(Rosenberger, 2006).
200
the west (Fig. 36). This region has historically experienced ephemeral inlet incision (i.e.,
Old Nye Inlet (Fig. 36) (G. Ballance, personal communication, 2006) during historic
times. Central Ocracoke Island and Ocracoke Village have not experienced the extensive
transgression that the NE end of Ocracoke Island has experienced during historic times
(Fig. 78).
The northeast end of Ocracoke Island, in contrast with central Ocracoke and
Ocracoke Village, contains back-barrier relict morphologies that are likely the result of
inlet activity (Fisher, 1962) (Fig. 36). GPR data were commonly indiscernible on this
section of Ocracoke Island and few channel geometries indicative of inlets were
encountered in the data. There are two reasons for this. The northeast end of Ocracoke
Island is commonly overwashed during storm events, which introduces saltwater into the
groundwater system that would attenuate the signal. The other explanation is that
northeastern Ocracoke Island has experienced ~1 km of landward transgression (Fig. 78).
Evaluation of historic maps shows that the modem location of NC FIighway-12 is
underlain by flood tide delta and overwash deposits at places on northeastern Ocracoke
(Fig. 78). Channel geometries encountered in GPR data could likely be relict flood tide
delta finger channels instead of relict inlet throat charmels. Five vibracores were acquired
on northeastern Ocracoke Island to characterize lithologic changes associated with inlet
activity and barrier island transgression (Fig. 71).
Vibracores OCR-05-S110 and OCR-05-S112 were acquired at the northeastern
end of Ocracoke Island (Fig. 68). Evaluation of historic maps (Fig. 78) shows that the
barrier has experienced more landward transgression at the locations of OCR-05-S110
201
and OCR-05-S112 than the locations of vibracores further to the southwest. Therefore, it
is expected that relict inlet throat channels in the NE are likely not preserved in the
underlying stratigraphic framework and channel geometries encountered in GPR data are
likely flood tide delta channels (Fig. 78). OCR-05-S112 recovered ~2.75 m of sediments
that were interpreted as sequential overwash deposits (Fig. 99). These overwash
sediments were likely deposited during the historically observed transgression of
northeastern Ocracoke Island. OCR-05-S110 recovered sediments characteristic of
sequential overwash deposits likely deposited during the historically observed
transgression of northeastern Ocracoke Island. An OSL sample on overwash sand from
~4.5 m below surface returned an age range of 278 to 120 yrs. B.P., which likely
corresponds with an overwash event during the historically observed transgression of
northeast Ocracoke Island.
Back-barrier relict inlet morphologies are encountered between the location of the
two northeastern vibracores (OCR-05-S110, OCR-05-S112) and the Pony Pasture area
(Fig. 68). Three other vibracores were acquired in the vicinity of the Pony Pasture area
on northeast Ocracoke Island (Fig. 97). The Pony Pasture area is characterized on
historic maps as a topographically low and generally unvegetated section of Ocracoke
Island with a large scale estuarine sand shoal body (Terrapin Shoal) existing directly to
the north. The topographically low Pony Pasture area likely experienced extensive
overwash during storm events, but existed as a sub-aerial feature during calm weather
conditions. Winds could have readily transported sediment from this unvegetated section
of Ocracoke Island and likely created a nearly shore-perpendicular aeolian dune ridge to
Core Core
RLBF LF Log G.P.R p.i.o o RLBF LF Log
G.P.R PI.
2(rW) -
. -.--M lb» 1
S *?* .
. “
_ .
^(shelly)
^(shelly) 1
- I Overwash
• ” • Overwash
—
S(rtd) 9®(shelly)
2-a ®(sheliy) ®(shelly)
®°(shelly) •
2-a 9®(shelly) ^
^(shelly) .^^Overwash
—
-Vl:SOverwash .# ‘? ? ?"
Q. Q. “®(shelly) /•" ''
—
? O) , •O) V • ?
Q Q
3- 4-b ^(mas)
: V- j
/ ^^^^^^—OverwashS(bur) ^(Shelly) %
L-
— ®(sheliy) I-':-'-; Overwash
_ *^(shelly) ®(shelly)
V T» *-41
—
^(lam) :S
^(shelly) {: 4 - b
' JÊ X^^Overwash
4-b ^(mas) Ovcr-s/ash 278-120
- - yrs. B.R 3
OCR-05-S110 OCR-05-SII;
Fig. 99. This figure illustrates the Radar-Litho-Bio-Facies (RLBF), lithofacies (LF) (lithofaeies legend in Fig. 51), GPR data
adjacent to vibracore, paleoenvironmental interpretations (PI), and age analyses for vibracores OCR-05-S110 and
OCR-05-S112. Pis in black were not assigned an RLBF value and were made solely on supplemental data. An OSL
age is shown.
203
the north (D. Ames, personal communication, 2006) (Fig. 97). Vibracore OCR-05-S108
(Fig. 100) was acquired near the dune ridge at the northeastern end of the Pony Pasture
area (Fig. 97). Vibracore OCR-05-S109 (Fig. 100) was acquired at the southwestern
edge of the Pony Pasture area (Fig. 97), which marks the transition between central and
northeast Ocracoke Island.
Vibracore OCR-05-S108 is located on a peat platform. An OSL sample on flood
tide delta deposits ~4.8 m below surface returned an age range of 476 to 408 yrs. B.P.
and restricts the age of the peat at the location of OCR-05-S108 to less than -400 yrs.
The peat is overlain by -0.5 m of modem overwash and has grown on top of sediments
deposited adjacent to the western edge of an active inlet throat channel (Fig. 100). A
complex sequence of inlet throat and flood tide delta deposits was encountered downcore
in OCR-05-S108 (Fig. 100). Paleoenvironmental interpretations made on this vibracore
indicate past inlet activity at the site of OCR-05-S108 and may explain the relict inlet
morphology of the modem back-barrier directly northeast of the Pony Pasture area (Fig.
97).
Vibracore OCR-05-S109 was acquired at the southwestern edge of the Pony
Pasture area which marks the transition from the morphologically different central and
northeastern regions of Ocracoke Island (Fig. 97). Central Ocracoke Island has
experienced minor barrier transgression during historic times (Fig. 78). Since central
Ocracoke Island appears to be more resistant to erosion than northeast Ocracoke Island, it
is conceivable that central Ocracoke Island was at one time an island and northeastern
Ocracoke was a sub-tidal shoal. Rosenberger (2006) described a similar evolution for
Core Core
Q RLBF LF Log G.P.R P.l. Age
—
S(ftd)
sP
—
^(lam)
®(shetly)
®(lam)
-
S(rtd)
•^(mas)
Q.
0) 4-d "'^S(bur,
Q 3- 3-c
®°(shellyj
^(shelly)
2-b ^(shelly)
2-c rnSjrtd;, ^6-408
yrs. B.P.
OCR-05-S108 OCR-05-S109
100. This figure illustrates Radar-Litho-Bio-Faeies (RLBF), lithofacies (LF) (lithofacies legend in Fig. 51), GPR data
adjacent to vibracore, paleoenvironmental interpretations (PI), and age analyses for vibracores OCR-05-S108 and
OCR-05-S109. Pis in black were not assigned an RLBF value and were made solely on supplemental data. Two OSL
ages are shown.
205
Portsmouth Island on the opposite side of Ocracoke Inlet to the southwest. Relict
recurved inlet spits at the site of OCR-05-S109 are morphological evidence for conditions
similar to those described by Rosenberger (2006) for Portsmouth Island to have existed at
the site of OCR-05-S109 (Fig. 97). LIDAR data at the site of OCR-05-S109 reveal relict
recurved spits associated with the southeastern edge of an inlet (Fig. 97), possibly
indicating central Ocracoke Island once existed as an individual island. Sediments at ~2
to 4.5 m below surface in vibracore OCR-05-S109 reveal at least four fining upward
sequences characteristic of inlet throat channel-filling (Fig. 100). OSL analysis was
performed on burrowed muddy sands interpreted as estuarine deposits at ~5.2 m below
surface in OCR-05-S109 (Fig. 100) and returned an age range of 1903 to 1619 yrs. B.P.
which agrees with the timing of estuarine conditions documented in vibracore PS03 in
southern Pamlico Sound (Grand Pre, 2006). The estuarine deposits from OCR-05-S109
and PS03 (Grand Pre, 2006) were likely deposited at a time when there was a barrier
present with an active inlet in the region and brackish estuarine conditions existed in
southern Pamlico Sound.
Portions of Ocracoke Island likely existed as individual islands prior to -1200 to
1100 yrs. B.P. Following this period, Ocracoke Village and central Ocracoke Island
likely existed as individual subaerial islands surrounded by adjacent sub-tidal shoals until
-500 to 400 yrs. B.P. The modern subaerial configuration of continuous Ocracoke Island
formed soon after -500 to 400 yrs. B.P. creating a restricted estuarine environment in
southern Pamlico Sound. Inlets incised into the younger sections of Ocracoke Island (i.e.,
northeastern Ocracoke and area between central Ocracoke and Ocracoke Village) and
206
overwash events created the molar tooth morphologies present on central Ocracoke
Island. Multiple historically documented inlets existed on the northeastern end of
Ocracoke Island prior to and during the opening of Harteras Inlet in 1846 (Fisher, 1962;
G. Ballance, personal communication, 2006) (Table 1) (Fig. 36). Only ephemeral inlets
have occurred on Ocracoke Island since Harteras Inlet has been active (Fisher, 1962)
(Table 1).
Summary of Holocene Geologic Evolution
The Holocene geologic evolution of the Outer Banks is strongly connected to the
antecedent topography (Riggs et al., 1995). The modem orientation and configuration of
the Outer Banks is the result of a complex history of barrier island formation and
destruction. The Outer Banks barrier chain has experienced shifts from continuous to
semi-continuous to discontinuous (Figs. 101, 102) as result of climate-controlled sea-
level fluctuations and variability in storminess during the Holocene.
Approximately 18,000 yrs. B.P. during the last glacial maximum, sea level was
-120 m below modern mean sea level (Fairbanks, 1989) and the location of the ocean
shoreline in places was up to 100 km east of the modem shoreline (Riggs and Ames,
2003). During this period of lower sea level, fluvial processes eroded the Pamlico Creek
drainage basin creating a topographically higher interstream divide at the modem
location of the Outer Banks. Harteras Flats Interstream Divide (HFID) is a relict
interstream divide that separates the fluvial drainage of paleo-Pamlico Creek to the
207
CONTINUOUS
BARRIER CHAIN
- Continuous barrier chain with minimal inlet
activity relative to semi-continuous and
discontinuous barrier chains
- Continuous barrier creates closed estuary
where brackish conditions exist with minimal
ocean circulation occurring only near inlet(s)
SEMhCONTINUOUS
BARRIER CHAIN
- Combination of individual islands and
continuous sections of the barrier chain
separated by both inlet channels incised below
mean sea-level and shallow sub-tidal shoals
- Semi-continuous barrier creates restricted
embayment locally where barriers are present
and open marine conditions locally where
sections of the barrier are non-existent
DISCONTINUOUS
BARRIER CHAIN
- Individual islands separated by both inlet
channels incised below mean sea-level and
shallow sub-tidal shoals
- Discontinuous barrier allows for open marine
circulation creating an open bay environment
Fig. 101. Illustration explaining the differences between continuous, semi-
continuous, and discontinuous barrier chains. The regions shaded black represent
subaerial barrier islands and the gray arrows indicate marine circulation through
breaches in the barrier chain. The Outer Banks barrier chain has transitioned from
continuous to semi-continuous to discontinuous in response to climate driven
fluctuations in sea-level and storm frequency and/or intensity. The scenarios
illustrated are arbitrary examples and do not represent the nature of the Outer
Banks barrier chain.
208
N OF CAPE NATTERAS YEARS S OF CAPE NATTERAS
TO OREGON INLET B.P. TO OCRACOKE INLET
Modern continuous configuration of barrier
chain established. Mostly ephemeral inlet
activity. Modern continuous configuration of barrier
chain established. Brackish conditions in
Semi-continuous barrier chain with active southern Pamlico Sound
inlets at least at Salvo, the Kinnakeet region,
and Avon -500-
Continuous/Semi-continuous barrier chain.
More continuous barrier chain
Barrier chain gradually becoming more continuous.
Semi-continuous barrier chain with active
inlets at least at the Kinnakeet region and Discontinuous/Semi-co5nfinuous barrier chain in exis-
Rodanthe 1000 fence. Gulf Stream sub-tropical wafers and open bay
conditions in southern Pamlico Sound
Continuous/Semi-continuous barrier chain
Semi-continuous Barrier Chain with restricted established. Brackish conditions in southern
embayment conditions in central Pamlico Pamlico Sound
Sound at least at the Gull Island and southern
Salvo Day Use areas 1500
I
Gradual growth of 2000barrier chain from
discontinuous to semi-continuous.
Gradual growth of barrier chain from
discontinuous to semi-continuous.
2500 More brackish conditions in southernPamlico Sound
Discontinuous Barrier Chain with open
embayment conditions present at least at the
Gull Island and Southern Salvo Day Use areas
3000
Discontinuous barrier chain established with Discontinuous barrier chain established with
individual islands likely existing individual islands likely existing at Cape
Harteras, Harteras Village, and Ocracoke
3500 Village, Open bay conditions in southern
Pamlico Sound
HFID overtopped, sediment HFID overtopped, sediment
accumulation accumulation
creating beach ridges atop HFID >400 creating beach ridges atop HFID
Fig. 102. Figure summarizing the geologic evolution of the Outer Banks north and south
of Cape Hatteras for the last 4000 years. Summary based on data from this study,
Smith (2004), Ricardo (2005), Culver et al. (2006, in prep.). Grand Pre (2006),
Rosenberger (2006), and Twamley (2006).
209
west and an unnamed fluvial drainage to the east (Fig. 3). The HFID served as the
foundation for the modern Outer Banks (Riggs, 1995; Riggs and Ames, 2003). Warming
global temperatures caused sea level to rise and begin flooding the paleo-Pamlico Creek
drainage basin -8000-7000 yrs. B.P. (Riggs and Ames, 2003; Culver et al, in prep.). Sea
level continued to rise and eventually flooded over the top of the HFID -4100 yrs. B.P.
(Culver et al., in prep.) changing the estuarine southern Pamlico Sound to a marine-
influenced embayment. Marine sediments began accumulating on the HFID soon after it
was flooded by sea-level rise -4100 yrs. B.P. (Culver et ai, in prep.). Accumulation of
sediments on the HFID continued until large portions of a barrier chain were created
-3700 yrs. B.P. (Culver et ai, in prep.) The relict beach ridges at Cape Hatteras,
Hatteras Village, and Ocracoke Village were likely formed during this time. The
formation of Cape Hatteras and associated cross-shelf shoal system affected the location
and direction of shelf currents. The Cape features, in turn, controlled the depositional
and erosional processes north and south along the Outer Banks. The segments of the
Outer Banks to the north (Oregon Inlet to Cape Hatteras) and south (Ocracoke Inlet to
Cape Hatteras) of Cape Hatteras have experienced similar patterns of evolution, however
with dissimilar chronologies.
South of Cape Hatteras, a continuous barrier chain formed by -3700 yrs. B.P.,
prohibiting Gulf Stream filaments from entering the Pamlico basin (Culver et al., in
prep.). Cape Hatteras, Hatteras Village, Ocracoke Village, and Portsmouth Village were
likely the original sites of island formation. This continuous chain of barrier islands
existed until -1200-1100 yrs. B.P. when large portions of this barrier chain must have
210
collapsed allowing shallow Gulf Stream filaments to flow into the open bay conditions of
southern Pamlieo basin (Grand Pre, 2006; Culver et al., in prep.). It was not until ~500
yrs. B.P. when large sections of the barrier south of Cape Harteras began to reform into
their modem configuration (Rosenberger, 2006; Twamley et al, 2006; Culver et al, in
prep.) and more restrieted estuarine conditions returned to southern Pamlico Sound. A
continuous barrier island chain has existed south of Cape Harteras to Ocracoke Inlet since
500 yrs. B.P.
The barrier chain north of Cape Harteras to Oregon Inlet has also experienced
transitions from continuous to semi-continuous to discontinuous in nature during the late
Holocene (Smith, 2004; Ricardo, 2005; Culver et al, 2006). Open marine conditions
existed in the south Salvo region as early as ~3000 yrs. B.P. (Ricardo, 2005) indicating
the barrier chain north of Cape Harteras was likely discontinuous at this time. From
-3000 yrs. B.P. to -1200 yrs. B.P. the barrier chain grew more continuous and restricted
embayment conditions were created locally at areas such as the south Salvo region
(Ricardo, 2005) and southern Salvo Day Use area (Table 6). From -1200-750 yrs. B.P.
the barrier chain was cut by inlets (e.g., Kinnakeet Complex Inlet, Rodanthe Non-
Migrating/Complex Inlet). The Kinnakeet Complex Inlet was active -1150 yrs. B.P.
(Table 7) and the Rodanthe Non-Migrating/Complex Inlet was active -950 yrs. B.P.
(Table 7). For inlets to exist, barriers must have existed in these regions at these times.
From -750-550 yrs. B.P. the Kiimakeet Complex Inlet was closed creating a more
continuous barrier chain north of Cape Harteras to Oregon Inlet. From -550-275 yrs.
B.P. migrating shallow complex inlets incised and migrated across 1-5 km sections of the
211
Outer Banks creating a semi-continuous barrier chain. These inlets likely were active for
many decades to as long as two centuries.
The Avon, Kirmakeet, and Salvo regions (excluding the south Salvo and southern
Salvo Day Use areas) experienced these larger scale shallow inlets. It is unclear if the
region north of Salvo to Oregon Inlet experienced similar large scale inlet activity during
-550 - 275 yrs. B.P. Two explanations exist for the lack of GPR data indicating similar
increase in large scale inlet activity during this time from Salvo to Oregon Inlet section.
This region did not experience the increase in inlet activity that occurred south of Salvo.
Second, this section did experience similar migrating complex inlet activity, but the
record of such activity has been eroded by barrier transgression since the end of inlet
activity.
Inlet activity from -275 yrs. B.P. to present has been sporadic between Cape
Hatteras and Oregon Inlet, allowing the barrier chain to maintain a predominantly
continuous nature with many ephemeral inlets (<100 years) (e.g.. New Inlet, Loggerhead
Inlet, Chickinaccommock Inlet, etc.) and one semi-permanent inlet (>100 years) (e.g.,
Oregon Inlet).
Correlation of Inlet Activity to Holocene Climatic Events
Climate variability appears to influence coastal paleoenvironmental change (Sager
and Riggs, 1998; Riggs, 2000; Scott et al., 2003; Havholm et al., 2004; Ricardo, 2005;
Grand Pre, 2006; Rosenberger, 2006; Twamley et al, 2006; Mallinson et al., in review;
212
Culver et al., in prep.). Figure 103 illustrates the relationship between climate events
during the Holocene and paleoenvironmental change on the Outer Banks. More frequent
and intense tropical storms produced by the warmer climate during the Medieval Warm
Period (MWP, ~1200-625 yrs. B.P.) (Mayewski and Bender, 1995) perhaps aided in the
destruction of sections of the Outer Banks, creating a discontinuous to semi-continuous
barrier chain. A more discontinuous barrier chain south of Cape Hatteras resulted in
open marine conditions in southern Pamlico Sound during the MWP (Culver et al, in
prep.). During the Little Ice Age (LIA, -625-175 yrs. B.P.) (Mayewski and Bender,
1995) sections of the Outer Banks became more continuous with multiple large scale
inlets (i.e.. Salvo, Kinnakeet, and Avon complex inlets).
A period of increased inlet activity (-550 to 275 yrs. B.P.) was identified before
the first detailed maps were made -1800 A.D. of the Outer Banks (Fig. 103). Two inlets
were known to have been active (Kinnakeet Complex Inlet and Rodanthe Non-
Migrating/Complex Inlet) -1150-700 yrs. B.P. (Fig. 103). Once these inlets (and likely
others) closed, a more continuous barrier chain was created north of Cape Hatteras.
The region from Cape Hatteras to Oregon Inlet likely experienced greater increase
in inlet activity from -550-275 yrs. B.P. than the section south of Cape Hatteras during
this same period. This could possibly be explained by an increase in nor’easter
occurrence and intensity during this time. Noren et al. (2002) discovered millennial-scale
variability in storminess during the Holocene in lake deposits in the northeastern United
States. They found that storminess (typically nor’easters) appears to have been
increasing in New England since -600 yrs. B.P. Nor’easters often affect broader regions
213
! Period of Increased Inlet Activity from -550 to 275 B.P.
Fig. 103. Figure summarizes age estimates from several studies on the Outer Banks from
Oregon Inlet to Ocracoke Inlet. An increase in inlet activity possibly related to
increased nor’easter activity north of Cape Hatteras was experienced during the
Little Ice Age from -550-275 yrs. B.P. The English settlers arrived during this
period of increased inlet activity. Most inlets were active prior to the
construction of the first detailed maps of the area -1750-1800 A.D.
214
of the Atlantic coast than hurricanes and the storms experienced in New England could
have affected the Outer Banks.
Implications for Continued Development along the Outer Banks
Inlets commonly occur at areas where inlets have previously existed. Between
40 and 70% (probably closer to the higher figure) of the Outer Banks from Oregon Inlet
to Ocracoke Inlet has at one time experienced one or more inlets. Once modest coastal
towns on the Outer Banks have developed into widely popular vacation towns in the past
few decades and continued growth is expected in future decades. The towns of Rodanthe
and Salvo are partially underlain by relict inlets and Avon is entirely underlain by relict
inlet channel-fill.
The formation of Isabel Inlet in 2003 occurred at a narrow section of the barrier at
the site of a previously active inlet. Narrower sections of the Outer Banks are probably
more susceptible to future inlet openings than wider sections. Since Rodanthe, Salvo,
and Avon currently exist on relatively wide sections, it is not likely that these sections be
breached in the near future. However, the present study discovered that a large-scale
inlet (Kinnakeet Complex Inlet) was active ~1150 yrs B.P., remained closed for at least
~600 years, and reopened at its original site ~500 yrs. B.P. With continued sea-level rise
and increasing tropical storm intensity (Emanuel, 2005; Webster et al., 2005), future
breaches may occur on wider island segments such as Rodanthe, Salvo, and Avon.
215
Knowledge of inlet history on the Outer Banks is imperative for future planning to
minimize property loss.
SUMMARY AND CONCLUSIONS
1. The lithologic, geophysical, and paleoenvironmental framework of relict inlet
channel-fill and adjacent facies from Oregon Inlet to Ocracoke Inlet on the Outer
Banks ofNorth Carolina was defined by combining GPR (2-D and 3-D),
lithologic, and foraminiferal datasets as paleoenvironmental indicators.
2. 3-D GPR offers additional insight into the complex nature of inlets including
directions of sediment transport.
3. As much as 70% of the Outer Banks from Oregon Inlet to Ocracoke Inlet (not
including Cape Hatteras, Hatteras Village, and Ocracoke Village) had relict
channel geometries in the shallow (<7 m below surface) subsurface.
4. Three varieties of inlets were defined by channel geometry, migrating nature, and
cut/fill patterns from GPR data along the Outer Banks: non-migrating/single inlet,
non-migrating/complex inlet, and migrating complex inlet.
5. A summary of GPR data reveals regional patterns of occurrence of radar facies.
a. Migrating complex inlets are most abundant from Salvo south to Cape
Hatteras (excluding the southern Salvo Day Use area and south Salvo
regions).
b. The northeastern end of Ocracoke Island characteristically has shallow
attenuation of the GPR signal due to frequent and extensive overwash and
high rates of barrier transgression.
217
6. Two expected proof of concept OSL age estimates on lithologic units of known
age confirm the use of OSL techniques for dating inlet channel-fill sands
deposited in shallow marine environments.
7. Different environmental development histories exist for the regions to the north
and south of Cape Hatteras during the late Holocene.
8. Around 3500 - 3000 years ago the barrier islands north and south of Cape
Hatteras were largely discontinuous with individual islands present. The barrier
islands in both regions gradually became more continuous until ca. 1300-1200
years ago; south of Cape Hatteras was more continuous than north of Cape
Hatteras.
9. Around 1200 to 1100 years ago open marine conditions existed in southern
Pamlico Sound indicating that the barrier islands south of Cape Hatteras
experienced a partial collapse likely leaving the chain as discontinuous with a few
individual islands. However, restricted embayment conditions existed in central
Pamlico Sound around 1300-1200 years ago indicating a more continuous barrier
system to the north of Cape Hatteras than to the south. At least two (Kirmakeet
Complex Inlet and Rodanthe Non-Migrating/Complex Inlet) inlets were active
during this period. The southern barrier system steadily grew more continuous
until ca. 500 years ago and the northern barrier system remained fairly stable until
ca. 550 years ago.
218
10. Around 500 years ago the barrier islands south of Cape Hatteras had a
configuration similar to the modem system. However, the barrier system to the
north experienced an increase in large scale shallow inlet activity causing the
islands to become discontinuous to semi-continuous until ca. 275 years ago when
these areas closed making the northern system more continuous again. From
-550 to 275 yrs. B.P., migrating complex inlets breached multiple regions of the
northern barrier islands (i.e., Salvo, Kinnakeet, and Avon regions) at times
simultaneously. The southern barrier system did not experience the same increase
in inlet activity as the northern barrier chain.
11. Approximately 275 years ago the modem configuration of the Outer Banks was
established from Oregon Inlet to Ocracoke Inlet. Since this time, inlets have
occurred in response to single storm events and have been more ephemeral (e.g..
New Inlet).
12. Increased inlet activity (ca. 550-275 yrs. B.P.) correlates with the Little lee Age
(ca. 625-175 yrs. B.P.) and could reflect an increase in storm activity.
13. Defining the spatial distribution of relict channels in the shallow subsurface of the
barrier island system is imperative for future management practices and
prevention of property loss.
REFERENCES
Aitken, M.J., An Introduction to Optical Dating: The Dating ofQuaternary Sediments by
the Use ofPhoton-stimulated Luminescence. Oxford: Oxford University Press,
267 p.
Ames, D.; Riggs, S., Sager, E., Wenell, B,, Havholm, K., and Whittecar, R., 2000. The
evolution of Jockey’s Ridge Dune Field, Nags Head, NC. Southeast Geological
Society ofAmerica Abstracts with Program, SEGSA Regional Meeting,
Charleston, SC, 2 p.
Andersen, H. V., 1953. Two new species of Haplophragmoides from the Louisiana coast:
Contributions from the Cushman Foundation for Foraminiferal Research, v. 4, p.
21-22.
Applin, E. R., Ellisor, A. E., and Kniker, H. T., 1925. Subsurface stratigraphy of the
coastal plain of Texas and Louisiana: American Association ofPetroleum
Geologists, Bulletin, v. 9, p. 79-122.
Earnhardt, W.A., Gonzalez, R., Kelley, J.T., Neal, W.J, Pilkey, Jr., O.H., Jose, H., and
Dias, J.A., 2002. Geologic evidence for the incorporation of flood tidal deltas at
Tavira Island, southern Portugal. Journal ofCoastal Research, Special Issue 36,
p. 28-36.
Boggs, S., 2001. Principles ofSedimentology and Stratigraphy. Prentice Hall, NJ, 725
P-
Bradley, R.S., 1999. Paleoclimatology: Reconstructing Climates of the Quaternary.
International Geophysics Series 64, Harcourt, San Diego, CA, 613 p.
Brady, G. S., and Robertson, D., 1870. The ostracoda and foraminifera of tidal rivers with
an analysis and description of the foraminifera: Annals and Magazine ofNatural
History, v. 6, p. 273-309.
Bristow, C.S., Chroston, P.N., and Bailey, S.D., 2000. The structure and development of
foredunes on a locally prograding coast insights from ground-penetrating radar
surveys, Norfolk, U.K. Sedimentology, v. 47, p. 923-944.
Burdette, K., Mallinson, D., Riggs, S., and Thieler, E.R., 2003. Ground Penetrating Radar
Investigations of the Paleoshoreline Features in Currituck County, North
Carolina: Defining the Geologic Framework and Sea-Level Implications.
GSA Abstracts with Programs, v. 35, no. 6, p. 490.
220
Burdette, K., Mallinson, D., Riggs, S., Culver, S., Brooks, G., and Thieler, E.R., 2004.
Chronostratigraphy and Geologic Framework of the Currituck Sand Ridges,
Currituck County, North Carolina. GSA Abstracts with Programs, v. 36, no. 5, 69
P-
Burdette, K., 2005. Chronostratigraphy and Geologic Framework of the Currituck Sand
Ridges, Currituck County, North Carolina. Master’s Thesis, Fast Carolina
University, 184 p.
Chappell, J., Omura, A., Fsat, A., McCulloch, T., Pandolfi, M., Pillans, J., 1996.
Reconciliation of late Quaternary sea levels derived from coral terraces at Huon
Peninsula with deep sea oxygen isotope records. Earth and Planetary Science
Letters, v. 159, p. 57-70.
Cole, W.S., 1931. The Pliocene and Pleistocene foraminifera of Florida: Bulletin Florida
State Geological Survey, v. 6, p. 7 - 79.
Collins, F.S., 1996. Marsh-estuarine foraminiferal distribtions and Holocene sea-level
reconstructions along the South Carolina coastline. Dissertation Thesis, Dalhousie
University, Halifax, 204 p.
Collins, F.S.; Scott, D.G., and Gayes, P.T., 1999. Hurricane records on the South
Carolina coast: can they be detected in the sediment record? Quaternary
International, v. 56, p. 15-26.
Culver, S.J. and Horton, B.P., 2005. Infaunal marsh foraminifera from the Outer Banks,
North Carolina, U.S.A. Journal ofForaminiferal Research, v. 35, no. 2, p. 148-
170.
Culver, S.J., Woo, H.J., Oertel, G.F., and Buzas, M.A., 1996. Foraminifera of coastal
depositional environments, Virginia, U.S.A.: distribution and taphonomy.Pa/a/05,
V. ll,p. 459-486.
Culver, S.J., Ames, D.V., Corbett, D.R., Mallinson, D.J., Riggs, S.R., Smith, C.G.,
and Vance, D.J., 2006. Foraminiferal and sedimentary record of late Holocene
barrier island evolution. Pea Island, North Carolina: the role of storm
overwash, inlet processes, and anthropogenic modification. Journal ofCoastal
Research, v. 22, p. 836-846.
Culver, S. J., Grand Pre, C. A., Mallinson, D. J., Riggs, S. R., Corbett, D.R., Foley, J.,
Hale, M., Ricardo, J., Rosenberger, J., Smith, C. G., Smith, C.W., Snyder, S.W.,
Twamley, D., Farrell, K., Horton, B.P., (in review). Late Holocene barrier island
collapse: Outer Banks, North Carolina, U.S.A. EOS.
221
Culver, S.J., Grand Pre, C.; Mallinson, D.; Riggs, S.R.; Corbett, D.R; Snyder, S.W.;
Farrell, K.; Horton, B.P.; and Hillier, C., inprep. Past and future barrier island
collapse: Outer Banks, North Carolina, U.S.A.
Cushman, J.A., 1922. Results of the Hudson Bay Expedition 1920.1. The Foraminifera:
Canadian Biological Board, Contributions to Canadian Biology, v. 9, p. 135-147.
Cushman, J.A., 1944. Foraminifera from the shallow water of the New England Coast:
Cushman Laboratoryfor Foraminiferal Research, Special Publication, no. 12, 37
P-
Cushman, J.A., 1947. New species and varieties of Foraminifera from off the
southeastern coast of the United States: Contributions from the Cushman
Laboratoryfor Foraminiferal Research, v. 23, p. 86-92.
Donnelly, J.P.; Roll, S.; Wengren, M.; Butler, J.; Lederer, R., and Webb, T., Ill, 2001a.
Sedimentary evidence of intense hurricane strikes from New Jersey. Geology, v.
29, p. 615-618.
Donnelly, J.P.; Bryant, S.S.; Butler, J.; Dowling, J.; Fan, L.; Hausmann, N.; Newby,
P.M.; Shuman, B.; Stem, J.; Westover, K., and Webb, T., Ill, 2001b. A 700-year
sedimentary record of intense hurricane landfalls in southern New England.
Geological Society ofAmerica Bulletin, v. 113, p. 714-727.
Donnelly, J.P., Butler, J., Roll, S., Wengren, M. and Webb, T. Ill, 2004. A backbarrier
overwash record of intense storms from Brigantine, New Jersey. Marine Geology,
V. 210,p. 107-121.
Ehrenberg, C.G. 1840. Das grossere Infusorienwerke. Konigliche Preussischen Akademie
der Wissenschaften zu Berlin Bericht, p. 198-219.
Emanuel, K., 2005. Increasing destmctiveness of tropical cyclones over the past 30
years. Nature, v. 436, p. 686-688.
Fairbanks, R.G., 1989. A 17,000-year glacio-eustatic sea level record: influence of glacial
melting rates on the Younger Dryas event and deep-ocean circulation. Nature
V. 342, p. 637-642.
Fichtel, L. von, and Moll, J. P. C., von, 1798. Testacea microscópica, aliaque minuta ex
generibus Argonauta et Nautilus, ad naturam picta et descripta (Microscopische
und andere Klein Schalthiere aus den Geschlechtern Argonaute und Schiffer): vii,
123 p., 24 pL, Camesina (Wien).
222
Fisher, J.J., 1962. Geomorphic Expression of Former Inlets along the Outer Banks of
North Carolina. Unpublished Master’s Thesis, University of North Carolina,
Chapel Hill, North Carolina, 120 p.
Fisher, J.J., 1967. Developmental Pattern of Relict Beach Ridges, Outer Banks Barrier
Chain, North Carolina. Unpublished PhD Dissertation, University of North
Carolina, Chapel Hill, North Carolina, 250 p.
Fitzgerald, D.M., Baldwin, C.T., Ibrahim, N.A., and Humphries, S.M., 1992.
Sedimentologic and morphologic evolution of a beach-ridge barrier along an
indented coast: Buzzards Bay, Massachusetts. Quaternary Coasts of the United
States: Marine and Lacustrine Systems, SEPM Special Publication no. 48, p. 65-
75.
Foley, J.A., in prep. Sedimentological and Foraminiferal Indicators of Holocene
Environmental Change in Pamlico Sound, North Carolina. Master’s Thesis,
East Carolina University, Greenville, NC.
Folk, R.L., 1974. Petrology ofSedimentary Rocks. Texas: Hemphill Publishing Co.,
182 p.
Foyle, A.M., and Oertel, G.F., 1997. Transgressive systems tract development and
incised-valley fills within a Quaternary estuary-shelf system: Virginia irmer shelf,
USA. Marine Geology, v. 137, p. 227-249.
Friedman, G.M., 1961. Distinction between dune, beach, and river sands from their
textural characteristics. Journal ofSedimentary Petrology, v. 31, no. 4, p. 514-
529.
Godfrey, P.J., and Godfrey, M.M., 1976. Barrier Island Ecology of Cape Lookout
National Seashore and Vicinity, North Carolina. National Park Service
Scientific Monograph Series, no. 9, 160 p.
Goldstein, S.T. and Watkins, G.T., 1999. Taphonomy of salt marsh foraminifera: an
example from coastal Georgia. Palaeogeography, Palaeoclimatology,
Palaeoecology,\. 149, p. 103-114.
Grand Pre, C.A., 2006. Holocene Paleoenvironmental Change in the Pamlico Sound,
North Carolina: Foraminiferal and Stable Isotopic Evidence. Master’s Thesis,
East Carolina University, Greenville, NC. 189 p.
Grossman, S. and Benson, R.H., 1967. Ecology of Rhizopodea and Ostracada of southern
Pamlico Sound region. North Carolina. The University ofKansas Paleontological
Contributions, v. 44, p. 1-90.
223
Gutierrez, B.T., Uchupi, E., Driscoll, N.W., and Aubrey, D.G., 2003. Relative sea-
level rise and the development of valley-fill and shallow-water sequences in
Nantucket Sound, Massachusetts. Marine Geology, v. 193, p. 295-314.
Hale, M.E., in prep. Late Holocene Geologic Evolution of Ocracoke Island, Outer
Banks, North Carolina. Master’s Thesis, East Carolina University, Greenville,
NC.
Havholm, K.G., Ames, D.V., Whittecar, G.R., Wenell, B.A., Riggs, S.R., Jol, H.M.,
Berger, G.W., and Holmes, M.A., 2004. Stratigraphy of back-barrier coastal
dunes, northern North Carolina and southern Virginia. Journal ofCoastal
Research, v. 20, p. 980-999.
Hawks, F.L., 1858. History ofNorth Carolina 1663-1729: with Maps and Illustrations.
Fayetteville: J. Hale & Son.
Hazel, J.E., 1977. Use of certain multivariate and other techniques in assemblage zonal
biostratigraphy: examples utilizing Cambrian, Cretaceous, Tertiary Benthic
invertebrates. In: Kauffman, E.G., and Hazel J.E., (Eds.) Concepts and
Methods ofBiostratigraphy. Stroudsburg, PA. Dowden, Hutchinson and Ross,
Inc.,p. 210-211.
Hayes, M.O., 1980. General morphology and sediment patterns in tidal inlets.
Sedimentary Geology, v. 26, no. 1-3, p. 139-156.
Hennessy, J.T. and Zarillo, G.A., 1987. The interrelation and distinction between flood-
tidal delta and washover deposits in a transgressive barrier island. Marine
Geology, v. 78, no. 1-2, p. 35-56.
Heron Jr., S.D., Moslow, T.F., Berelson, W.M., Herbert, J.R., Steele III, G.A., and
Susman, K.R., 1984. Holocene sedimentation of a wave-dominated barrier-island
shoreline: Cape Lookout, North Carolina. Marine Geology, v. 60, p. 413-434.
Hippensteel, S.P. and Martin, R.E., 1999. Foraminifera as an indicator of overwash
deposits, barrier island sediment supply, and barrier island evolution: Folly Island,
South Carolina. Palaeogeography, Palaeoclimatology, Palaeoecology, v. 49, p.
115-125.
Jol, H.M., Smith, D.G., 1995. Ground penetrating radar surveys of peatlands for oilfield
pipelines in Canada. Journal ofApplied Geophysics, v. 34, p. 109-123.
224
Jol, H.M., Smith, D.G., and Meyers, R.A., 1996. Digital Ground Penetrating Radar
(GPR): A new geophysical tool for coastal barrier research (examples from the
Atlantic, Gulf, and Pacific Coasts, U.S.A.). Journal ofCoastal Research, v. 12,
no. 4, p. 960-968.
Jol, H.M., Lawton, D.C., and Smith, D.G., 2002. Ground penetrating radar; 2-D and 3-D
subsurface imaging of a coastal barrier spit. Long Beach, WA, USA.
Geomorphology, w. 53, p. 165-181.
Jomp, J., 2006. Quaternary Lithostratigraphy, Biostratigraphy, Seismic Stratigraphy
and Geologic History of the Buxton-Avon Area, North Carolina. Master’s
non- thesis paper. East Carolina University, Greenville, NC, 21 p.
Kornfeld, M. M., 1931. Recent littoral Foraminifera from Texas and Louisiana:
Contributionsfrom the Department ofGeology ofStanford University, v. 1, p. 77-
101.
Lario, J., Spencer, C., Plater, A.J., Zazo, C., Goy, J.L, and Dabrio, C.J, 2002. Particle size
characterization of Holocene back-barrier sequences from North Atlantic coasts
(SW Spain and SE England). Geomorphology, v. 42, p. 25-42.
Linne, C., 1758. Systema naturae per régna tria naturae, secundum classes, ordines,
genera, species, cim characteribus, differentiis, synonymis, locis: G. Engelmann,
Lipsiae, ed., v. 1, p. 1-824.
Madsen, A.T., Murray, A.S., Andersen, T.J., Pejrup, M., Breuning-Madsen, H., 2004.
Optically stimulated luminescence dating of young estuarine sediments; a
comparison with ^’°Pb and '^^Cs dating. Marine Geology, v. 214, no. 1-3, 30 p.
Mallinson, D., Ames, D., Riggs, S., Crowson, R., Foster, N., and Hoffman, C.,
2001. Ground-penetrating radar defines the Holocene and Pleistocene geology of
the North Carolina Outer Banks. Abstracts with Program, GSA National Meeting,
Boston, Nov. 2001, 166 p..
Mallinson, D., Riggs, S., Thieler, R., Culver, S., Foster, D., Corbett, R., Farrell, K.,
Wehmiller, J., 2005. Late Neogene and Quaternary evolution of the northern
Albemarle Embayment (mid-Atlantic continental margin, USA), Marine Geology,
V. 217, p. 97-117.
Mallinson, D.J., Burdette, K.E., Brook, G.A., Mahan, S.A., in review. Optically
Stimulated Luminescence Age Controls on Marine Isotope Chron 5, 3 and 1
Coastal Lithosomes: North Carolina, USA. Quaternary Research.
225
Mallinson, D., Riggs, S., Culver, S., Ames, D., Farrell, K,, and Crowson, R., in review.
Barrier island response to Holocene sea-level and climate change (northern
North Carolina Outer Banks, USA). Journal ofCoastal Research.
Mallinson, D. J., Culver, S. J., Riggs, S. R., Thieler, E.R., Foster, D., Wehemiller, J.,
Farrell, K., Pierson, J., Buckner, M., (in review). Regional seismic stratigraphy
and controls on the Quaternary evolution of the Mid-Atlantic Passive Margin;
Cape Harteras Region, North Carolina, USA. GSA Bulletin.
Mayewski, P.A., and Bender, M. 1995. The GISP2 ice core record-paleoclimate
highlights. Reviews ofGeophysics Supplement, US National Report to the lUGG
1991-1994, p.1287-1296.
McBride, R.A., and Robinson, M.M., 2003. Geomorphic evolution and geology of Old
Currituck Inlet and its flood tidal delta, Virginia/ North Carolina, USA (Part I).
Coastal Sediments '03, American Society ofCivil Engineers Press, Reston, VA,
14 p.
Mello, J.F., and Buzas, M.A., 1968. An application of cluster analysis as a method of
determining biofacies. Journal ofPaleontology, v. 42, p. 747-758.
Montagu, G., 1808, Testacea Britannica; supplement. Exeter, England: S. Woolmer, 183
P-
Montfort, Denys de, 1808. Conchyliologie systématique et classification méthodique des
coquilles: v. 1, Ixxxvii, 409 p.
Moslow, T.F., and Heron, S.D., Jr., 1978. Relict inlets; preservation and occurrence
in the Holocene stratigraphy of southern Core Banks, North Carolina. Journal
ofSedimentary Petrology, v. 48, p. 1275-1286.
Moslow, T.F., and Tye, R.S., 1985. Recognition and characterization of Holocene tidal
inlet sequences. Marine Geology, v. 63, p. 129-151.
Munsterman, D. and Kerstholt, S., 1996. Sodium polytungstate, a new non-toxic
alternative to bromoform in heavy liquid separation. Review ofPalaeobotany and
Palynology, v. 91, p. 417-422.
Murray, J.W., 1969. Recent foraminifers from the Atlantic continental shelf of the
United States. Micropaleontology, v. 15, p. 401-419.
Natland, M.L., 1938, New species of foraminifera from off the West Coast ofNorth
America and from the later Tertiary of the Los Angeles Basin: Bulletin ofthe
Scripps Institution of Oceanography, University ofCalifornia, v. 4, p. 137-164.
226
Noren, A.J., Blerman, P.R., Steig, E.J., Lini, A., and Southon, J., 2002. Millenial-scale
storminess variability in the northeastern United States during the Holocene
epoch. Nature, v. 419, p. 821-824.
d’Orbigny, A., 1839. Foraminiferes, In Sagra R. de la, Histoire physique, politique et
naturelle de File de Cuba: A. Bertrand, Paris, 224 p.
Parham, P.R., 2003. The Quaternary Lithostratigraphy, Seismic Stratigraphy, and
Geologic History of the Croatan Sound Area, North Carolina. Master’s Thesis,
East Carolina University, Greenville, NC, 110 p.
Parham, P.R., Riggs, S.R., Culver S.J., Mallinson, D.J., and Wehmiller, J.F., in
prei'i. Quaternary depositional patterns and sea-level fluctuations. North
Carolina. Quaternary Research.
Phleger, F.B, 1960. Ecology and Distribution ofRecent Foraminifera. Johns Hopkins
Press, Baltimore, 297 p.
Ricardo, J.P., 2005. Late Holocene Paleoenvironmental Change of the Salvo-Gull Island-
Little Kinnekeet Area, Outer Banks, North Carolina. Master’s Thesis, East
Carolina University, Greenville, NC, 188 p.
Riggs, S.R., York, L.L., Wehmiller, J.F. and Snyder, S.W., 1992. Depositional Patterns
Resulting from High-Frequency Quaternary Sea-Level Fluctuations in
Northeastern North Carolina. Quaternary Coasts ofthe United States: Marine and
Lacustrine Systems, SEPMSpecial Publication, no. 48, p. 141-153.
Riggs, S., Cleary, W.J., and Snyder, S.W., 1995. Influence of inherited Geological
framework on barrier island morphology and dynamics. Marine Geology, v. 126,
p. 213-234.
Riggs, S.R., Rudolph, G.L., and Ames, D.V., 2000. Erosional scour and geologic
evolution of Croatan Sound, northeastern North Carolina. North Carolina
Department of Transportation, Report no. FHWA/NC/2000-002, Contract
Research Project 98-4, 116 p.
Riggs, S.R, and Ames, D.V., 2003. Drowning the North Carolina Coast: Sea-Level
Rise and Estuarine Dynamics. North Carolina Sea Grant, North Carolina State
University, Raleigh, N.C., 152 p.
Riggs, S.R, and Ames, D.V., in press. Storms and Barrier Island Dynamics on Core
Banks (1960-2001), Cape Lookout National Seashore, NC. North Carolina Sea
Grant, North Carolina State University, Raleigh, NC.
227
Rink, W.J., 1999. Quartz luminescence as a light-sensitive indicator of sediment
transport in coastal processes. Journal ofCoastal Research, 15, p. 148-154.
Robinson, M.M., and McBride, R.A., 2003. Old Currituck Inlet, Virginia/ North
Carolina: Inlet history documented by foraminiferal evidence (Part II).
Proceedings Coastal Sediments ’03 American Society ofCivil Engineers Press,
Reston, VA, 14 p.
Robinson, M.M., and McBride, R.A., 2006. Benthic foraminifera from a relict flood-
tidal delta along the Virginia/ North Carolina Outer Banks. Micropaleontology,
V. 52, p. 67-80.
Rosenberger, J.E., 2006. Late Holocene Back-Barrier Development of Portsmouth Island,
Outer Banks, North Carolina. Master’s Thesis, East Carolina University,
Greenville, NC, 185 p.
Rudolph, G.L., 1999. Holocene evolution of a drowned tributary estuary, Croatan Sound,
North Carolina: Department of Geology, East Carolina University, Greenville,
N.C, 237 p.
Sager, E.D., 1996. Holocene infill history of Albemarle Sound, North Carolina: an
integrated seismic-, litho-, and chronostratigraphic synthesis: Unpublished M.S.
Thesis, East Carolina University, Greenville, NC, 192 p.
Sager, E.D., and Riggs, S.R.,1998. Models for Holocene valley-fill history of
Albemarle Sound, North Carolina, U.S.A. In: Alexander, CR., Davis, R.A.,
and Henry, V.J.,(Eds.), Tidalites, Special Publication no. 61, p. 119-128.
Schnitker, D., 1971. Distribution of foraminifera on the North Carolina continental shelf.
Tulane Studies in Geology and Paleontology, v. 8, p. 169-222.
Scott, D.B.; Medioli, F.S., and Schafer, C.T., 2001. Monitoring in Coastal Environments
Using Foraminifera and Thecamaebian Indicators'. Cambridge University Press,
Cambridge, 177 p.
Scott, D.B., Collins, E.S., Gayes, P.T., and Wright, E., 2003. Records of prehistoric
hurricanes on the South Carolina coast based on micropaleontological and
sedimentological evidence, with comparison to other Atlantic Coast records. GSA
Bulletin, 115, p. 1027-1039.
Sedgwick, P.E. and Davis, R.A. Jr., 2003. Stratigraphy of washover deposits in Florida:
implications for recognition in the stratigraphic record. Marine Geology, v. 200,
p. 31-38.
228
Schwartz, R.K. and Birkemeier, W.A., 2004. Sedimentology and morphodynamics of a
barrier island shoreface related to engineering concerns, Outer Banks, NC, USA.
Marine Geology, v. 211, p. 215-255.
Shackleton, N.J., Pisias, N.G., 1985. Atmospheric carbon dioxide, orbital forcing, and
climate. In; Sunquist, E.T., Broecker, W.S. (Eds.), The carbon cycle and
atmospheric CO^: Natural Variations Archean to Present, Washington, D.C.,
American Geophysical Union, p. 303-317.
Simms, A.R., Anderson, J.B., and Blum, M., 2006. Barrier-island aggradation via inlet
migration: Mustang Island, Texas, Sedimentary Geology, v. 187, p. 105-125.
Smith, C.G., 2004. Late Holocene Geologic Development of Pea Island and Avon-
Buxton Area, Outer Banks, North Carolina. Unpublished Master’s Thesis, East
Carolina University, Greenville, North Carolina. 156 p.
Smith, C.G., Culver, S.J., Riggs, S.R., Ames, D., and, Corbett, D.R., in press.
Geospatial analysis of barrier island width of two segments of the Outer Banks,
North Carolina, USA: anthropogenic curtailment of natural self-sustaining
processes. Journal ofCoastal Research.
Stuiver, M., and Reimer, P.J., 1993. Extended '‘^C data base and revised CALIB 3.0
'"'C age calibration program. Radiocarbon, v. 35, p. 215-230.
Susman, K.R, 1975. Post-Miocene Subsurface Stratigraphy of Shackleford Banks,
Carteret County, North Carolina, Duke University, North Carolina, M.S. Thesis,
102 p.
Susman, K.R. and Heron Jr., S.D., 1979. Evolution of a barrier island, Shackleford
Banks, Carteret County, North Carolina. Geological Society ofAmerica Bulletin,
V. 90, p. 205-215.
Terquem, O., 1876. Essai sur le classement des animaux qui vivent sur la plage et dans
les environs de Dunquerque, Paris, no. 1, p. 1-54.
Terquem, O., 1878, Les foraminiferes et les entomostraces ostracodes du Pliocene
supérieur de Vile de Rhodes. Soc. Geol. France Mem., Paris, France ser. 3, v. 1, p.
1-135, pl. 1-19.
Thieler, E. R., Foster, D. S., Mallinson, D. M., Himmelstoss, E. A., McNinch, J. E., List,
J. H. (in review). Quaternary geophysical framework of the northeastern North
Carolina coastal system. USGS Open File Report.
229
Twamley, D.F, 2006. Holocene geologic development of Harteras Village area, Outer
Banks, North Carolina. Master’s Thesis, East Carolina University, Greenville,
NC.
Twamley, D.F., Culver, S.J., Mallinson, D.J., Riggs, S.R., and Corbett, D.R., 2006.
Holocene geologic development of Harteras Village area, Outer Banks, North
Carolina. Southeast GSA Abstracts with Programs, no 10, 51 p.
Walker, G., and Jacob, E., 1798. In Adams, G. (Ed.), Essays on the Microscope (2nd ed.):
London (Dillon and Keating).
Ward, L.W., Bailey, R.H., and Carter, J.G., 1991. Pliocene and early Pleistocene
stratigraphy, depositional history, and molluscan paleobiogeography of the
Coastal Plain. In: Horton, J.W., and Zullo, V.A., (Eds.), The Geology of the
Carolinas. University of Tennessee Press, p. 274-289.
Webster, P.J., Holland, G.J., Curry, J.A. and Chang, H.R., 2005. Changes in tropical
cyclone number, duration, and intensity in a warming environment. Science, v.
309, p. 1844-1846.
Williams, G.W., and Johnson, A.S., 1996. Tar Heel Maps: Colony and State 1590-
1995: North Carolina Wesleyan Press, Rocky Mount, North Carolina, 92 p.
Woo, H.J., 1992. Distribution of foraminifera and pollen in coastal depositional
environments of the southern Delmarva Peninsula, Virginia, U.S.A. Dissertation
Thesis, Old Dominion University, 298 p.
Woo, H.J., Culver, S.J., and Oertel, G.F, 1997. Benthic foraminiferal communities of a
barrier-lagoon system, Virginia, U.S.A. Journal ofCoastal Research, v. 13, p.
1192-1200.
Workman, R.R., Jr., 1981. Foraminiferal assemblages of the nearshore inner continental
shelf. Nags Head and Wilmington areas. North Carolina: Greenville: East
Carolina University, Master’s Thesis, 16Ip.
Appendix A:
Grain Size Analysis Results
Avonln-05-VC2 90-91 cm Phi MidPI Weight WelgM% Product Oevlatton OeviationZ Product Deviation} Product Devtation4 Product Cumulattve S
<-2 -2.25 000 000 0.00 -4.43 1956 O.X -6667 O.X 3X.52 OX OX
-15 -1 75 000 000 000 -3 93 1541 OX •60 46 OX 237 42 OX OX
-1 -1.25 0.00 0.00 O.X •3.43 11.73 0.x -1019 O.X 137 X O.X ox Avonln-0S-VC2 90-91 cm
-OS -075 002 003 •0.02 •233 856 026 •25.x •0 77 73 23 2*25 ox
0 -0.25 003 r*0.06 -001 -2 43 588 0 27 •14 27 -0 66 34X 1 59 ox Mtthod of Mwnenta
05 025 036 056 0.14 -1.93 3.71 205 •714 -3.x 13.74 7X ox Meen- 2.16
0.75 1.73 266 1.99 -1.43 203 5.'40 -2.x -7 69 413 10.97 329 Sod- 055
1.5 1 25 2.79 4.29 5.36 -0 93 0.86 3.67 -0 79 ^40' 073 3.14 7 57 Ske«v- ?0.27
? 1 75 16.38 2516 44.03 -0 43 018 456 -OX •194 OX 062 32 73
25 2J25 2842 43 66 98.21 007 001 0.24 OX OX OX OX 76 X
3 275 1251 1921 5284 0.57 033 6.34 0.19 365 0.11 2 10 9SS3
3.5 325 2.29 352 11.43 107 1.15 4X 124 4X 1 33 469 9911
3.75 027 0 41 156 157 2.48 i.ra 3X 1 62 615 255 99 52
>4 425 0 31 048 202 207 430 205 6X 425 1853 8 82 1X.X
....
65 11 100.00 217.54 2993 -4.» 44 53
Avonln-0S.VC2 197-198 cm Phi MidPt Weight Weights Product Déviation Deviation} Product Devlatioo4 Product Deviatlor»5 Product CumulattvcS
<•2 -2 25 15.19 14 61 -32 88 ‘-443 19 56“' 286 20 -86 67 ‘•1266 54 38352 S60491 14 61
-1 5 -1 75 2 51 2.41 -4 23 -3 93 15.41 37 21 -X4a -146X 237 42 573.M 17X
.1 -1.25 2.17 209 -2-61 -3.43 11.73 24X -4019 -X.91 137.x 287 41 19.12 Avonln-05-VC2 197-198 cm
•OS •0 75 453 436 -3.27 •2.93 8.56 37.x -25 X •1X11 73 23 31918 2348
0 •025 825 794 •1.98 •2.43 5.88 46.89 •1427 -11324 34X 274.X 31.41 Method ot Moments
05 025 12.40 11.93 296 •1.93 3.71 4422 •7.14 •6515 13.74 1X.94 43.34 Mmn- 0.37
1 0.75 1819 1750 1313 •1.43 2.03 35.56 -2X •X.68 4.13 72 23 X84 Sort- 2.x »
15 1.25 16.80 1616 20.20 -0.93 0.66 13.84 -0.79 -12.81 Ô73 ' 11.x 77.01 Skew- -1.53
2 175 1570 1510 26.43 -0.43 0.18 2.73 •0.x -1.16 OX 0.49 92.11
25 2.25 619 596 1340 0.07 001 OX OX OX OX O.X X.07
3 2.75 1 66 1 60 439 057 0.33 053 019 O.X 0.11 017 99X
35 3.25 019 0 18 059 1.07 1.15 0 21 1 24 0.23 IX 0.24 »X
375 006 006 0.22 1.57 248 0.14 3.x 023 6.15 O.X 99.x
>4 425 010 0 10 0 41 2 07 4.30 041 893 O.X 1853 1.78 1XX
103 94 100 00 36 79 529 57 -1X7 .X 731055
?
PN MidPI WeigM Weights Product Deviation Deviation} Product Ocvlatlof>4 Product Deviations Product Cumulatives
<-2 •2 25 036 048 -108 -4 43 19.58 936 -66.67 -41 44 363 52 183.x 0.48
-1 S -1 75 012 016 -0.26 -3 93 15.41 246 -X48 -9 64 237 42 37 84 064
-1 -1.25 0.18 024 -0.30 •3.43 11.73 2.81 -4019 -9.61 137.x 32.91 0.M Avonln-05-VC3 135-136 cm
•0.5 •0.75 0.46 0.61 •0.46 •2.93 856 523 •25.x •15.x 73 23 44 74 1 49
0 •025 1.07 1 42 •0.36 -243 568 8X •14,27 -X26 34.x 49.16 291 Method of Moments
05 025 2.82 3'75 0.94 -1 93 3.71 13.86 •714 -26 73 13.74 51.47 6X Mo«>- IX
1 075 893 1186 890 -1.43 2.03 24 10 -2.x -34X 4 13 4826 1852 Sort- OX
15 1.25 1469 1951 24.39 •093 086 1671 -0 79 •15.46 073 14.31 X.X Ska«- •1.x
2 1 75 22.85 »36 5311 •0 43 018 549 •0.x -234 OX 0.99 XX ''
?S 225 17.85 2371 53.34 0.07 0.01 0.13 OX 0.01 OX OX g2x
3 2.75 5.79 7.69 21.15 0.57 0.33 254 019 1.46 Oil 084 9977
35 3.25 0.14 0.19 0.60 1.07 1 15 0.21 1 24 0.23 1 X 025 XX
4 375 00? 003 010 1.57 ^2.48 007 3X 010 615 016 XX
>4 4.25 001 0.01 0.06 2.07 430 OX 8X 012 18 53 025 1XX
75 29 IKOO 160.12 91 40 -17321 465 28
 
 
? .Kimln-05-VCI 23S-ZM aií/ PN MMn WctgM Product OevUdon Deviation? Product Deviations Product Deviations Product Cumulative % . ^ L 1 1
<•? •2.25 2312 1918 -43.15 -4 43 1956 375 56 -66 67 -1661 99 383 52 7354 92 1918
•15 -1.75 12.63 10.46 -18.33 -3.93 15.41 161.42 •60 46 •633 63 237 42 2487.23 29.65
- - - -
•1 -1.25 12.46 10.34 •12.92 -3.43 11.73 121 26 -4019 -41537 137.66 142Z78 3999 Kmnin-05-VC1 235-236 cm
-05 -0 75 937 7.77 -5 83 -2 93 6.56 66 51 •2503 •194,57 73 23 568.18 47.76
0 •0.25 856 709 -1 77 •2 43 588 41 72 -14 27 -101 18 34 60 245.39 54 85 Mettwd ol Moments
05 025 659 5.47 1 37 -1.93 3.71 2026 ?7.14 -39.01 13.74 75.12 6032 Mean^ -0.12
1 075 6 71 5.57 4.17 -1 43 2.03 11 31 •290 -16.12 4.13 22.97 65.86 Sort- 2.84
1 5 1.25 6.91 5.73 7,16 -0.93 0.86 4.91 -0.79 -4,54 0.73 4.20 71,62 Skew* •1.34
7 1.7S 19.07 1582 27.68 -0.43 0.18 2.86 -0.06 ?1.22 0.03 0.52 87 43
75 2.25 11.39 945 21 26 007 001 005 000 000 0.00 0.00 9688
275 3.50 2.90 798 0.57 033 096 0 19 055 oil 0 32 99 78 *
. .
. 1 —
4 3.75 0.01 0.01 003 1 57 248 OCB 390 003 615 005 9992^
>4 4.25 010 006 035 2 07 430 036 693 0 74 18.53 1 54 100 00
120 56 100 00 • 11 59 807 35 -3066 IS 12164 39 ..
Kinnln-0S-VC2 M-67 cm PM MUPI WMoM MMaM% Product Déviation OevUtlonT Product Deviations Product OaviatlonS Product Cumulative %
<-7 -2.2S 029 041 ^92 19 58 7 97 -8667 ?35 27 383 52 156 10 041
-1.5 •1.75 0.00 0.00 0.00 •3.93 15.41 000 -60 40 000 237 42 0.00 0 41
.1 -125 000 0.00 0.00 -3 43 11.73 000 -40.19 0.00 137 66 0.00 0.41 Kinnln-05-VC2 66-«7 cm
-05 ?0.75 0.16 022 -017 •233 856 r« 1 -25 03 -5 62 73 23 16.45 063
-0.25 057 080 -020 -2.43 566 4,71 ?14 27 •11 41 34.60 27 68 143 Method of Moments
025 1 56 2.19 055 •1 93 3 71 8 12 -7.14 • 1563 1374 3009 3.62 Meen* ^1 62 A
1 075 5.90 641 6.31 -1.43 2.03 1706 -2.90 ?24 35 413 34 70 1203 Sort* 0.83 i- / \
15 1.25 1561 21.91 27 39 -0 93 086 1676 -0 79 -17.36 073 1606 33 94 Skew- -1.91 7\
2 1 75 32 92 46 20 80.86 -043 016 836 ?006 -3 56 0 03 I^ 1.51 X.14
25 2.25 999 1402 31.55 0.07 001 008 0.00 0.01 0.00 0.00 94 16 -
5.15 14 16 057 033 1.70 019 0.98 011 056 99 31 ? ? ? ? ? 1*^
15 325 044 062 2 01 1.07 1 15 071 1 24 on 1.33 082 99 93 1 -j -11 .1 at 2 ]• > » 4 4*^
4 376 002 0.03 011 1 57 246 0.07 390 oil 615 0.17 99 96
003 0.04 0 18 2 07 430 018 893 038 1853 0 78 100 00
71 25 100 00 161 81 69 66 -11096 264 33
, __— ,- .
Kinntn<05-VC2143-144 cm Phl MMPI WtklM Product Deviation Deviations Product DaviatlonS Product OevlatlonlO Product Cumulatives*
-2 26 529 669 -1505 -4 43 1956 130.97 •86 67 -579 59 383 52 2564 9*1“' 669
-1 5 •1.75 1 33 1.66 -2 94 493 15.41 25 91 •60 48 •101.70 237.42 399.20 8.37
-1 -125 0.43 0.54 -0 68 •3 43 11.73 6.38 -40.19 •21 85 137.66 74.84 6.91 Kinnln-05-VC2 143-144 cm
-05 •0.75 1 71 216 •1 62 -2 93 856 1650 -25 03 -54 12 73.23 158 32 11.07
39.27 •1427 •95 23 34 60 2X97 1775 Method of Moments
?
7SS 992 248 •1 93 3.71 36 79 -714 •70.83 1374 1X.38 27 67 Mem- 0.89
“
1 r^75 1334 16.66 1265 •1.43 203 34 26 -2.90 -48.84 413 68 61 44 54 Sort- 1.77
1 5 125 14 21 1796 22.46 -0 93 0.66 15 38 -0.79 -14.23 0.73 13.17 62.x Skew- •1.77
1 75 21 28 26 90 47.06 -0 43 018 4 87 •0 06 -207 0.03 0.88 89.41 Jt—r \ 1
75 225 564 713 1604 007 0.01 004 0.00 000 o.œ O.X 96 54
2 75 ?' 2.49 3.15 666 0.57 0 33 1 04 0.19 0.60 0.11 0.34 9968
15 3.25 0.17 021 070 1.07 1 15 0.25 124 027 1.33 029 99X > -1 .1 4* « «* 1 11 > U > M < 4
3.75 001 0.01 0.05 1.57 2.48 0.03 390 0.06 6.15 0.06 99.91 M.*—eM
038 2.07 4X 036 893 079 18.53 1 64 10000
7910 100 00 8853 314 06 •966 76 3650 63 -
— — ^ •L -i 1
 
.... \1 J 1
OCR-05-S1M 193-194 cm Phi MtdPt WttlgM% Product Duvtatton OevtationIO Product Deviattonll Product Dcv1atlon12 Product ^Cumulativa % I 1 1 1. .
‘ '
<•? .2-25 0.00 0.00 000 •4 43 19.58 000 ?86.67 0.00 ' 383.52 bw 000
-1 S -1.75 0.03 0.08 -014 -393 15.41 1.21 •60 48 -475 237 42 18.65 0.08
.1 •1.25 0.18 0.47 •0 59 •3.43 11,73 5.53 -40.19 J •18.94 137 66 64 89 0.55 OCR-O5--S108 193-194 cm
-05 -0.75 0.38 1.00 -0 75 •2 93 856 852 ?2503 •24 91 73.23 ^ 72 87 .1S4. _J
0.66 •0.16 -243 5.88 3.85 •14,27 -934 34 60 22œ ' 220 Method of Moments /
05 0.25 015 039 0.10 •1.93 3.71 1.46 -7.14 •2 80 13 74 540 259 M«n° 2.58 L
,
0.75 025 065 049 •1.43 203 1.33 •2.90 -1.90 4 13 2.70 3.25 So>1« 0.85 Í" /
1.5 125 0.37 0.97 1.21 .093 0.86 0.83 ?0.79 ?0 77 073 0.71 422 Skw» 001 r~\
1.75 1 81 4.74 829 •0.43 0.18 086 •0.08 •036 003 016 896
?5 2.25 9.01 23 59 53 08 0.07 0.01 0.13 000 0.01 0.00 0.00 3255 T
21.51 56.32 154.89 0.57 0.33 1860 019 10.69 011 6.14 88 87 V.^
JS 3» 1 72 4.50 1464 107 1.15 520 124 559 133 601_ 93 38 ?** •'* •’ » Í4 . 44 4 4 *l_ .
- -
—
>4 l“®~’ 4 43 1881 2.07 4.30 19.05 893 39 52 18.53 81 96 ÏÔOÔÔ '
36 19 100 00 258 12 72.01 062 295 67
. .
_ - . . J
—
OCR-05-S108 281-282 cm PhP MMPI W*JgM W«4aM% Produel Oevtatlon DevlattonlO Product OvrMionll Product D«vUtlon12 Product ! Cumutativ* % 1
<-? -225 0.00 0.00 0.00 -4.43 19.56 0.00 •86.67 0.00 363 52 0.00 0.00
•1 5 .175 0.01 002 ?0.03 -3.93 15 41 0.28 •60 48 •1 09 237 42 4.29 0.02
•1 0.00 000 000 •3.43 11.73 o.œ -4019 000 137.66 0.00 002 OCR-05-S108 281.282 cm
•05 -0 75 007 013 -0 09 -293 856 1 06 -2503 -317 73 23 926 0.14
0.04 •0 01 •2.43 5.88 021 •1427 -052 34.60 1 125 0.18 Method o( Moments V ,
004 007 002 •1 93 3.71 0.27 •714 -052 13 74 0.99 025 Mewt- 267 L
1 0.75 015 027 0.20 -1.43 2.03 0.55 •2.90 -0 78 4.13 1 12 052 Sort» 0.85 |- / \
1 5 1 25 040 0 72 090 -0.93 0.86 062 •0 79 -057 073 053 1 25 Sketv» 1 12 V 1
2 1.75 232 4 19 7.33 1 4D,43 0.18 0.76 •0.08 -0,32 0.03 014 544
75 225 853 1541 34 67 1 007 0.01 009 0.00 0 01 000 000 2085
2.75 39.54 71 42 196.41 0.57 033 23.59 019 1356 011 779 92 27
15 287 518 1685 1 07 1.15 599 1 24 643 133 691 97,45 % 4 .14 .t 44 • 1 14 ] >• 1 44 4 4
^
4 0.47 085 318 1 57 2.48 211 390 3 31 615 ' 96.30
..
4.30 7 31 893 1516 ^ 18 53 31 46 100.00
- 1 5S36 " 100 00 266 65 42 84 31 50 66 96
-
- — — —
. _
...
Product Deviation Deviationll Product OmrUtlon12 Product Oevtatk>n13 Product Cumulative %
" '
-;7 75- 0.00^ 000 000 "-4.43" 19 58 Ô C» -86.67' o'œ 38352 000 0.00
-1 5 -1 75 0.00 000 000 •393 1541 0.00 -60 48 oœ 237 42 r 000 000
•1 -125 000 000 000 •3 43 11.73 o.œ -40.19 0.00 13766 000 0.00 bCR-OS^iOS 309-310 cm
-7^ -0 75 0.00 000 000 -293 8.56 000 -2503 000 73 23 0.00 ox
6 -2.43 588 0.00 -14 27 000 34 60 000 ox Method of Moments
1 05 008 023 0.06 -193 3.71 086 •714 -166 13.74 318 023 Mean- 331^
0.75 019 055 041 -1 43 Z03 1.12 -290 -1 59 4.13 227 078 Sort» 1 36 }- r
1 5 1 25 0.44 1 27 1 se -093 0.86 109 -0 79 -1 01 0.73 0.33 2X Shev^ 1 28 r\ /
? 1.75 0.28 081 ??V4"2 -0 43 0.18 0.15 -0.08 -0.06 0.03 003 287 /- \. y
75 089 258 580 0 07 001 001 000 000 000 000 544
13.50 0.19 776 011 4.46 46.34 ------ ? ?
325 4.10 11.87 38 59 ^ 107 1.15 1371 124
14 74 I 133 15.84 58.21 ' 1 4 -1* .1 4t • *4 I 1» 1 14 > >S i 4
375 477 13.81 51.80 157 248 34.25 3.90 5393 615 84 93 72.02
>4 4?S^ 27.98 118.90 2.07 4.30 120.41 893 248.81 1853 518.27 IX X
34 53 10000 331 02 185.11 321 62991
—
1 1 i --- .rr 1
 
 
'OCR-(U-S1101S14SS^Sm J^1 1PN MMPI W«4gM W*lght% Product Owtatlon Dcv4atlon14 Product DcviattonIS Product Oevlatk>n16 Product Cumulative % 1 1 1 1
<?? -2 25 029 053 -1.20 -4 43 19.58 1044 -8667 -46.x 383 52 204 45 053
-15 •1.75 0.10 018 -0.32 -3 93 15.41 283 -60 48 -11.12 237.42 43 64 0.72
-1 -1.25 0.12 022 -0.28 -3.43 11.73 259 •4019 -8.87 137 66 X37 0.94 OCR-0S-S110 151-152 cm
-05 4)75 017 031 -0 23 ?2 93 856 267 -25 03 •7 82 73 23 ?n B<j 175 -
0 -0 25 039 0.72 •0.18 •243 5.68 422 -14 27 -10.23 34X 24 61 ^ 197 Method ot Idocnanti
05 025 069 127 0.32 -1.93 3.71 4.70 -7 14 -9X 13 74 1743 3 a Idevi- 1.x
0.75 257 4.72 3.54 -143 2.03 9.60 •2.x •13X 413 19.x 796 Sort* 076
15 1 25 568 10.44 13.05 •0.93 086 894 •0.79 -8.27 0 73 766 1840 Sk*»- •2.x r\
7 1 75 18.24 33 53 58.68 •0.43 018 607 -OX -2 58 O.X 1 10 51 S3
?s Í2S 19.25 35 39 7962 007 001 OX OX 0.01 OX OX 87 32
275 6.24 11 47 3154 057 0 33 379 019 2 18 oil 1 25 X7g ^ Vrr
15 3.25 046 085 275 1.07 1 15 096 124 1.x 1 X 1 13 XX » 4 .1» .1 4« > It > >S 6 < »
4 375 006 009 034 1 57 240 023 3X OX 615 057 X?2
>4 015 0 28 1 17 2.07 4.x 1 19 893 246 le.x 5.11 1XX
54 40 100 00 18881 ' 58 44 • 111 76 379 89
«UCRVSWiïo MMPt WelaM wiotint Product OcvMiofi 0«vlatk>n1S Product DovMlanI* Product ?•vtatfoni? Product Cumulativ* %
''
<-2 -2.25 0.00 000 000 -4.43 1958 0 00 -86 67 OX 363 52 OX OX
-15 -1 75 000 000 0.00 -393 15 41 000 -60 48 OX 237.42 OX O.X
-1 -1.25 0.00 0.00 0.00 -3.43 11.73 O.X •40-19 0.x 137X O.X O.X OCR-0S-S110 304-305 cm
-05 -0 75 0.01 002 -002 -293 856 0.21 -xra •062 73X VBI 002
0 -0 25 0.02 006 -0.01 -243 588 029 -1427 ?0.71 34X 1 71 0 07 Mettwd of Moments
05 025 005 012 0.03 •1 93 371 046 -7 14 -o.m 13.74 1 70 020 Mean* Z10 Í-
075 021 052 0.39 -1 43 203 1.05 •2.x -IX 4 13 214 072 Sort* 044 r\
15 125 1.53 3.78 473 •093 086 324 -079 -3X 073 2.77 Skew- -O.S
. . T—\
1 75 16.09 39 77 69.59 •0.43 0.18 7.x -OX -3.x OX
. .1._3P 44 27
~25' 1500 37.07 83.42 007 001 021 OX 002 OX O.X 81 34 7—\
1 275 725 1792 49.28 057 033 592 019 340 011 1» ^ X76
15 325 0.24 059 1 93 1.07 1.15 0.69 1 24 0.74 IX 0.79 X6S 4» 4 .1» .» -*t « «1 < IS > It > 11 < •
4 375 0.03 007 028 1 57 248 018 3X OX 615 046 XX ?^»s—*>s
>4 425 003 0 07 032 2.07 4 X 032 893 oœ iex 1 37 1XX
40 46 100.00 209 92 19 76 -4X 16.01
-
IHiimiÉWliÉCWtlIlBBtcni -4 Pili MMPt WelgM W«éoM% Product Dcvtatton DevIallonIS Product Devlatk>n16 Product O«vt0tton17 Product Cumulatlva %
<-? •2.25 0.00 000 000 -4 43 1958 OX -8667 OX 383 52 O.X OX
-15 -1 75 0.00 000 000 -3 93 15.41 0.x -60 48 ox X7 42 OX OX
-1 -1.25 0.02 0.04 •0.05 -3.43 11.73 047 -40.19 -1 sa 137 X 5.x 0.04 OCR-05-S110 475-476 cm
-05 -0 75 005 0.10 -0 07 -2.93 8.56 0.85 -25X -2.x 73 23 731 014
0.10 020 •0 05 -2.43 5.86 1 17 -14.27 •2X 34X 6 91 034 Method ot Moments
05 0.11 022 005 -1.93 3.71 0.81 -7.14 -1.57 13.74 302 O.X Mean- 247
1 0.75 018 036 027 -1.43 Z03 0-73 -2.x -1.04 4.13 1.48 O.X Sort* OX 1;; t \
1 5 1 25 033 066 082 -0 93 0.86 056 -0 79 •0.52 073 048 1 X Skm»- ' 0 14 1 V
7 175 319 6 37 11.14 ?0 43 018 1 15 •O.X ?0 49 OX 0 21 794
75 225 19.66 39 24 88.29 0.07 001 022 OX 0.02 0.x OX 4719 J\
140.46 0.57 OX 1687 0.19 9.69 Oil 557 X26 1 l„ »..l -?
15 3.25 080 1 60 5.19 1.07 1 15 1.84 1.24 1.x 1.x 213 XK 1 « 4 -1 41 St . n 1 It 1 It • «
3.75 006 012 045 1 57 2.48 OX 3X 0.47 6.15 0 74 X98 ' 1
0.02 0.06 207 4X OX 893 0.16 16.x 0.37 1X.X
5010 10000 246.60 25 07 1.77 X71
1 | i- , I-
 
 
 
 
 
 
0o 1 1 1 1SUn-05-VC2 2581-259 cm.^ Phi MIdPt WttaM wvighn; Product Deviation Devlatk>n25 Product Devlatk>n2e Product Devlatlon27 Product Cumulative % 1 1 1 1<-2 -2.2S 364 523 ?11.77 •4.43 1 19X 102 48 -X67 •453.51 383.52 2006 94 5 23-1 5 •175 1 23 177 .3X ^93 1541 27 25 •1XX 237 42 419.82 7.x —•1 .1.25 1.77 2.54 •3.18 •3.43 11.73 29.x -4019 -1X27 137.x 330.30 9.x SaNn-0S-VC2 258-259 cm?05 0 75 3.26 472 ?354 •293 856 40X -25 X -116.x 73.x 343.33 14.260 -0 25 381 548 -1 37 -243 5M 32 22 -14 27 -78 14 34X ^69S3 19.74 Method of MomenU05 025 414 595 1 49 -193 371 22X ?.7:1-4- ? -42 X 13.74 81.79 25X Mean» i.15??1 otT^*^61 663 4 97 -1.43 2.ra 13.x -2» -1919 4 13 27 35 3212 Sort» 1.» j-'?15 1.25 673 968 12X •093 OK 878 ?0 79 -7.67 073 7X 41 99 Ska<«> -1.x? 1.75 20 80 29 90 52 33 -0 43 018 5 41 •O.X •2 30 O.X 0» 71 B9?5 225 1439 2069 46 55 007 001 012 OX 0 01 OX OX 92X / \3 2.75 4.84 6.96 1913 0.S7 033 730 0.19 1 32 0.11 0.76 X5435 3;?5_. 077 0.39 1 26 1.07 1.15 0.45 124 ^OX 1.x 0.52 99.93 * J IS s »s . .- — -. VJ— —">4 425~ “‘dÔ2‘ ' ~o"^' 012 2.07 430 0.12 8X 026 18‘X ^o'x îxdô’.69 56 100X 115.15 284 47 928 32 3431 20S«ln-05-VC3 108-107 cm MWPI WMaM W»laM% Product Deviation DevlatlonZS Product DevlatlonM Product Deviation27 Product Currailatlve %<-2 -2 25 1.74 2 79 ?«27 -4.43 19.5a 54X .86 67 -241 50 383 52 t~ïôe9.io 2.79.15 -1 75 089 143 •250 •3 93 15.41 21.97 -XX -K24 237.42 338 52 ?*.2J .•1 •1.25 •1.82 -3.43 11.73 17.11 •40.19 -XX 137.x 2X.70 567 Sann-0$-VC3106-107 cm.05 0 75^ 1 29 207 -1 55 -293 6.x 1789 -25.x 51 74 73 23 151 35 7 74312' -0.78 -2 43 5.U 18X -1427 -44.57 34X 1X10 10.x Method of Momants— 1025 220q3H - 088 •1.93 3Z' 13 07i-7.14 •25.16 13.74 XX 14X Maan> 1.x1 075 5.02 604 ^ 603 -1.43 2.x 1634 -2» -23 29 4.13 X20 22X Sort» 1.34 Í-15 1.25 7.49 i2.m 1S.X -0.93 086 1027 -0.79 -9.51 0.73 8» 3443 Sheiv •Í26 7^? 1 75 1939 31 06 54.36 -0 43 0.18 5.62 -O.X ?2 39 0.x 1.x X4g25 225 1669 26 74 1" 6016 007 001 000 OX OX 92 23 ......
»17 —^ V
•
35 ’’ 325 0.43 b.69 224 107 1 15 080 Î.24 “ OK 1.x 0.92 XX ' J 4 -M 4S . .. . .s J 21 > »S S .
4 375 007 011 0 42 1 57 248 026 3» 044 6.1s OX 99 97
>4 003 ÓÍ4 2 07 430 0 14 8X 029 18.x O.X 1XX
62 42 IXX 145 39 176X 54016 196217
S<ln-05-VC3 402-403 cm MMPt WMaM Product Deviation Devlatton2< Product Deviatioft27 Product Deviatloi>28 Product Cumulative %
<-? -2.26 661 ^11 ^-24 99 -4.43 19X 217.49 -X.67 -g62X 383 52 42X19 11.11
.1 5 -1 75 365 4.71 •8 24 -393 1541 72.54 •XX •264 75 237 42 1117 74 1581
.1 •1.25 612 789 -9.87 ?3.43 11.73 92.62 -40.19 -317.25 137.x 10XX 23.71 Salln-05-VC3 402-403 cm
?05 075 “484^ 6.24 •4.x -2.93 ex X.42 •25.x •1X20 73 23 457.18 29 95
-2.43 sx 29.x ' -14.27 34.x 175 84 XX McttMd of Moments
05 dá”' 481 620 1 SS -1.93 3.71 23.x -7.14 -44.28 13.74 85 26 41 24 Mean- 0.41
1 0.75 979 11 96 8X -1 43 2X 24 34 -2.» -34 70 413 XX 53 22 Sort- 2 31 j-
15 1 2$ 1332 17 18 21 48 O.X bx 1471 ?0.79 •1361 0 73 12X 70 40 -1.M^ Skaw
1 75 15.30 19.73 34 54 -0.43 0.16 357 -O.X -1 52 O.X OX »13
5.46 707 15» 007 0.01 0.04 OX OX OX OX 97 20
3 275 191 2.46 677 0.57 OX 0 81 0.19 0 47 0.11 0 27 99 X
35 325 0.18 023 075 1 07 J 1.15 027 124 029 1.x 0 31 X» 4» 4 -li -1 as • (1 1 IS 2 2S > >S < «
4 375 0.03 0.04 015 1.57 2.48 0.10 3.» 0.15 615 024 X94
027 4.30 026 8.x OX 18X 1 19 1XX
IXX 4135 533X •18KK 72X61 —
-
— ?-T— ! ^^^
 
...) . ..._ . _. . 1 1 1 1
’
<?7 -2 2S 401 628 -14 14 1956 123 07 •X67 -544 63 383.52 241016 6.28
-1 S -1.75 1.48 2.32
^ -4.x' -393 15.41 X74 -60.46 -140.28 237 42 SX.67 8.x
.1 -1.25 0.49 0.77 -ox -3.43 11.73 9.01 -40.19 -X.X 137.x 1X.71 9.37 SalvoDUA-0$-S5B 124-125 cm
ofT* -0 75 1.41 2.21 -1 X -293 8.x 18.91 •25.OT -55 32 73 23 161 83 11 se
-1 K -2.43 5X 24X •14.27 -60 37 34.x 146.41 1581 Method of Momenta
427 669 1 67 •1.93 371 24.81 ^ -7.14 -47.76 13.74 91.x 22X Me»»- 1.x
1 075 935 1465 10.99 -143 2.x 29 77 -2.x -42.43 4.13 x.4e 37.16 Sort- 1.x k
1 s 1 25 642 1320 1649 •093 OX 11 X -0.79 •10X 0.73 9.x X.35 Skav- •1.x
?'
1 75 1699 26 63 ' «60 -0 43 0 18 482 •OX -2X OX 087 76.x
75 2.25 10.89 1707 36 40 007 001 010 o.x 001 OX OX 94 04
275^ 3.56 55» 1534 057 0.33 1 84 019 IX 011 0.61 99 62
3 25^ • M 1 It022 0.34 112 1 07 1 15 040 124 043 1 33 046 X97 ?” " '
3 75- 002 003 012 1 5’7 248 OX 3X 1 012 615 019 1XX,
OX ox 2 07 4X ox 8X OX 18 S3 OX 1XX
63 81 1XX r 1XX 294 72 -932 54 3^.04
.
-
-1 r.— [:i: :? —TT 1 - — — — -— .. -?- _ ^
-Salví5OUAS0»S8 Pht MMPt Weight viWaM% Product Deviation OevUtlon2t Product Deviation^ Product DevIatlonSO Product Cumulative %~ —
'
<•: •2‘25 7.21 897 -2018 -4’43 19M 175X -86.67 ~-7T7Âr 383 52 3440.x e'97
-1 5 -1.75 3.15 3.92 -6X -3.93 15.41 X.X -60.48 •237.x 237.42 930.54 12.x
.1 •1.25 286 3.56 •4 45 •3 43 11.73 41.75 •40.19 -143.02 137X 4XX 16.45 S«lvoDUA-05-SSB 216-217 cm
4)5 -0 75 1 39 1 73 -1 X •2 33 8X 14X -25.x •43X 73 23 126X ^ 18.18
0 -025 1 68 2X •0 52 -2.43 S.X 12X •1427 •29 82 34X 72 33 20 27 Method of Moments
072 •1 93 3 71 10 X -714 •M 51 13.74 39X 23.14 Mew>« 1.x
075 7.46 928 6X •1.43 2X 18 X -2.x ^•26 X 4.13 X.31 3243 Soit- 1 M |-
1 5 1 25 9.23 11 48 14X •0 93 O.K 9X -0.79 •9.10 0.73 8.42 43.91 Skmv- •1 S3
7 1.75 24.30 X.24 52 91 -0 43 0.18 547 •O.X -2.x O.X OX 74.14 —
75 225 17.01 21 16 47 62 0.07 0.01 012 ox 0 01 o.x OX X31
366 10X 0.57 033 1 X 019 OX 011 040 X.X » ? - -
35 3.25 034 0.42 1 37 1.07 1.15 049 1.24 053 1.x O.X X W t .J -I 4* • M 1 ti > H 1 >» 4 4
375 0.04 005 0.19 1.57 248 012 3X 019 6 15 0.31 X43 •rWM.rM
>4 0.57 243 2.07 4.x 246 893 511 1853 10X 1X.X
80 37 1X.X 1X.28 354 14 -1282X 51X11 L.
Appendix B:
Raw Counts of Foraminifera Specimens
SalvoUUA
Kinnln-05- Kinnln-05- Kinnln-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- Oreln-06- 05-S3B Salln-05-
SI 288- VC1 155- VC2 209- S108 281- SI 08 309- S108 416- S108 445- SI 09 203- SI 09 505- S110151- S110 304- S110 475- Sill 151- sill 320- S112 116- S112 275- VC1 132- 317-318 VC1 503-
289 cm 156 cm 210 cm 282 cm 310 cm 417 cm 446 cm 204 cm 506 cm 152 cm 305 cm 476 cm 152 cm 321 cm 117 cm 276 cm 133 cm cm 504 cm TOTAL
Ammonia parkinsoniana 65 2 5 20 24 0 0 3 2 0 6 12 0 0 4 0 0 10 154
Asterigerina carinata 0 0 0 1 0 1 0 1 0 1 1 2 0 3 0 0 0 0 0 10
Buccella inusitata 4 0 0 5 0 2 0 0 0 0 2 3 0 0 0 3 0 0 2 21
Cibiddes lobatulus 0 0 0 5 2 1 0 2 0 2 6 7 0 4 4 3 0 0 0 36
Elphidium excavatum 228 20 55 166 238 5 10 58 20 18 107 191 0 34 10 106 14 13 86 1379
Elphidium galvestonense 15 0 0 6 5 1 1 2 0 5 2 8 0 8 3 1 0 1 16 74
Elphidium gunteri 3 0 0 2 0 1 0 1 0 1 1 0 0 5 0 0 0 16
Elphidium macellum 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 3
Elphidium mexicanum 0 0 1 16 0 1 0 0 0 0 4 6 0 0 3 2 0 0 1 34
Elphidium sp~ 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 4
Elphidium subarcticum 1 0 1 2 0 0 0 0 0 0 0 3 0 0 1 3 0 0 1 12
Eponides répandus 0 0 0 0 0 0 0 0 0 0 1 0 0 0 2 0 0 0 0 3
Eponides sp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1
Hanzawaia strattoni 4 0 4 11 1 2 0 2 0 0 9 14 0 0 0 6 1 4 59
Haplophragmoides sp. 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1
Haphphragmoides wilberti 0 0 0 0 0 0 1 0 0 0 0 0 5 0 0 0 0 0 0 6
Haynesina germánica 0 0 0 4 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13
Indeterminate rotaliid 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1
Nonionella atlántica 0 0 0 1 0 0 0 3 0 0 2 6 0 1 0 0 0 0 1 14
Quinqueloculina jugosa 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 3
Quinqueloculina lamarckiana 0 0 0 0 0 0 0 0 0 0 6 0 0 0 0 1 0 0 0 7
Quinqueloculina seminula 0 0 3 5 0 2 0 14 0 0 10 19 0 1 3 6 0 0 0 63
Quinqueloculina sp. 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 2
Trochammina infíata 0 0 0 0 0 0 3 0 0 0 0 0 30 0 0 0 0 0 0 33
TOTAL: 320 22 70 244 279 18 15 86 22 27 159 276 36 52 29 143 15 15 121
¡ 1 i i ? 1 : :
Planktonics 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2
Appendix C:
Alphabetical List of Foraminifera Taxa Included in the Cluster Analysis
with References to Original Publications and Figures
252
Ammonia parkinsoniana (d’Orbigny): Rosalina parkinsoniana d’Orbigny, 1839, p. 99,
pi. 4, figs. 25-21.
Asterigerina carinata d’Orbigny: Asterigerina carinata d’Orbigny, 1839, p. 118, pi. 5,
fig. 25, pi. 6, figs. 1-2.
Buccella frigida (Cushman): Pulvinulina frigida Cushman, 1922, p. 14.
Buccella inusitata (Andersen): Eponidesperuvianas d’Orbigny, 1929, p. 10, pi. 4, fig.
5a-c.
Cibicides lobatulus (Walker and Jacob): Nautilus lobatulus Walker and Jacob, 1798, p.
642, pi. 14, fig. 36.
Cibicides refulgens de Montfort: Cibicides refulgens de Montfort, 1808, p. 123, p. 122,
text fig.
Elphidium discoidale (d’Orbigny): Polystomella discoidalis d’Orbigny, 1839, p. 56, pi. 6,
figs. 23, 24.
Elphidium excavatum (Terquem): Polystomella excavata Terquem, 1876, p. 20, pi. 2,
figs. 2a, b.
Elphidium galvestonense Komfeld, Elphidium gunteri Cole var. galvestonensis, Komfeld,
1931, p. 87, pi. 15, fig. 1.
Elphidium gunteri Cole: Elphidium gunteri Cole, 1931, p. 34, pi. 4, figs. 9, 10.
Elphidium macellum (Fichtel and Moll): Nautilus macellus Fichtel and Moll, 1798, p. 66,
pi. 10, figs. h-k.
Elphidium mexicanum (Komfeld): Elphidium incertum var. mexicanum Komfeld, 1931,
p. 89, pi. 16, figs. 1,2.
Elphidium subarcticum Cushman: Elphidium subarcticum Cushman, 1944, p. 27, pi. 3,
figs. 34, 35.
Elphidium translucens Natland: Elphidium translucens Natland, 1938, p. 144, pi. 5, figs.
3,4.
Eponides répandus (Fichtel and Moll): Nautilus répandus Fichtel and Moll, 1798, p. 35,
pi. 3, figs. a-d.
Hanzawaia strattoni (Applin): Truncatulina americana Cushman var. strattoni Applin in
Applin and others, 1925, p. 99, pi. 3, fig. 8.
253
Haplophragmoides wilberti Andersen: Haplophragmoides wilberti Andersen, 1953, p.
21, pi. 4, fig. 7.
Haynesina germánica (Ehrenberg); Nonionina germánica Ehrenberg, 1840, p.203.
Miliamina fusca (Brady): Quinqueloculina fusca Brady in Brady and Robertson, 1870, p.
47, pi. 11, figs. 2, 3.
Nonionella atlántica Cushman: Nonionella atlántica Cushman, 1947, p. 90, 91, pi. 20,
figs. 4, 5.
Poroeponides lateralis (Terquem); Rosalina lateralis Terquem, 1878, p. 25.
Quinqueloculina jugosa Cushman: Quinqueloculina seminulum (Linne) wav. jugosa
Cushman, 1944, p. 13, pi. 2, fig. 15.
Quinqueloculina lamarckiana d’Orbigny: Quinqueloculina lamarckiana d’Orbigny,
1839, p. 189, vol. 8, pi. 11, figs. 14, 15.
Quinqueloculina lata Terquem: Quinqueloculina lata Terquem, 1876, p. 82, pi. 11, figs,
a-c.
Quinqueloculina seminula (Lirme): Serpula seminulum Linne, 1758, p. 786, pi. 2, fig. la-
c.
Rosalina floridana (Cushman): Discorbis floridanus Cusman, 1922, p. 39, pi. 5, figs. 11,
12.
Trochamina inflata (Montagu): Nautilus inflatus Montagu, 1808, p. 81, pi. 18, fig. 4
Appendix D:
Individual Value Plots of Equivalent Dose for Vibracores and
Histograms Plotting Number of Measurements Vs. Equivalent Dose for
Each OSL Sample
Individual Value Plot of Equivalent dose vs Well
dEqouivsalent
Individual Value Plot of Equivalent Dose vs Well
Well
Individual Value Plot of Equivalent Ikise vs Well
Individual Value Plot of Equivalent Dose vs tAAell
 
De values obtained from Avonln-VC3 (L45-L60)
0.05 0.10 0.15 0.20 0.25 0.30 0.35
Equivalent Dose (Gk^ys), n= 22(38)
De values obtained from Avonln-VCS (Z41-Z56)
De Values Obtained From Kïnnln-VCl (L60-1.75)
[)e values obtained from Kinnln-VCl (Z38-Z54)
Mean 0.2815
StDev 0.05931
N 19
0.18 0.23 0.28 0.33 0.38 0.43
Equivalent Dose (Gteys), n=19 (20)
[>e values obtained from Kinnln-VC2 (L45-L60}
 
[>e values obtained from OCR 5108
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Equilalent EHise (Greys)^ n=19 (30)
De values obtained from OCR 5109
 
De values obtained from Oreln VCl (Z98-3.16)
De values obtained from Oreln-VCl (3.16-3.41)
De values obtained from Rodin-VC1(Z00-Z 15)
De values obtained from Rodln-VCl(4i44'4h59)
 
De values obtained from Salín-VC1(S15-5L31)
 
 
De values obtained from SalvoDUA-S5B(Z86'3^06)
10-
Mean 0.2417
Lpir-i StDev 0.1664
8 N 20
<y
£
6-
Vi
fü
0» 4-
o
=1* 2-
.... • • -.??orX-.'Jf'-.- ?
0 I-
0.0 0.2 0.4 0.6 0.8
Equivalent Dose (Gtays), n: 20(35)
Appendix E:
Summary of Radar-Litho-Biofacies Data, Biofacies Data, Lithologic
Core Illustrations, Ground Penetrating Radar Data,
Paleoenvironmental Interpretations, and Age Estimates for Each
Vibracore Acquired
Core Core
o LF Log GPR P.l. LF Log GPR RI. Age
5; 'verwash
^(mas)
®(lann)
^(mas)
®(shelly)
?? j Inlet‘
Q.
O) ®°(she»y)
Q
— 3®(5he#y) 428-338
®°(sheHy) yrs. B.P.
—
Ávonln-05-VC1 Avonln-05-VC2
Core Core
Core
LF Log G.P.R RL
o
II fl
9^(rtd) Overwash
1 r.;
/ Sait
sP ' T' '> Marsh
^(rtd)
Z \ Z
2 — 9^(gr)
— iNpBIF Estuarine
Shoal
gs/
^(lam) • - -?
y,- »:
3
gS/ -?T. \ *
^(lam) •• • • • Estuarineï‘ -jmiSÈiii Shoal
i-'-.T F,. ^
• “"«P
?*- • V r ?
4 gS/ ?•-O r
^(lam)
LÊ
5
Chicln-05-S1
Core Core
Core Core
LF Loq G.P.R p.i.
-- -
: ®(rtd)
_
S(rtd) : V-: Dverwash
p,i,i,i - ®(slwlly)
sP Salt
Marsh
-
- «aavi ®(lam)
1 -
^(lafn) Inlet ^(shelly)
^(Shelly)
't ”
- ®(lam) fc..'-: 4 - a
Estuarir^
Shoal
—
~
Z ~
S(rtd) *°(she«y)l- z
®®(shelly)l
?- FloodQ. - ;? Tide Q. *®(shelly)l
<D 4-d 'nS,b„, - . Delta <U 0^(8heliv)l
Q
3- Q3-c "?-^(buri Tide —
Delta ®®(sf>€illy)l
*®(shelly)
zz
Inlet S(lam)
®(she»y) Channel
; V-
inlet
2-b ®(shellyj Channel 3-c ^903-1619
2-c 'T'Sirt,,, FloodTide ^6-408 yrs. B.P.
I .r yrs. B.P.
*
OCR-05-S108 OCR-05-S109
Core Core
RLBF LF Log G.P.R p.l.o Age®(nd)
^(Shelly) Overwash
—
Back-
^(Shelly) ®(r1d)Overwash -
^{shelly) F ^^mma
— Overwash
S(rtc)) ®(lam)^(Shelly)
V -"^ÊUÊÊÊl Estuarine
2 - a ^(•hetty) 1 ^^(rtd) Shoal
^
^‘^(sheiiy) ¿V-:
—
^(mas)
®(stielly) Overwash
Overwash £ A
wr ^ ^(shelly)
?"^ishelly) SI
D. 9®(shelly Overwash
-:-y Q)
Q ®(shelly) Flood.
4 - b ^(mas) iJVx:./.
Z~ CM o ®(bur) "to * .. Delta
®(bur) 1
®(she)ly) j— r
Dverwash 1
— ’°(she«y)
^{shelly)
S(lam)
^(shelly) 278-120
4 - c ®(mas) - I
5 yrs. BP. 5
OCR-05-S110 OCR-05-S111
Core Core
RLBF LF Log G.P.R Rl. Age Log G.P.R Rl. Age
^(shelly)
®(sheHy)
-
S(rtd)
9^(sheliy)
_ 9®(shelly)
1 ®(shelly)- sP
2-a ^^(sheKy)9®(sh*l)y) S(rtd) ^3-277
yrs. B.P.
(m) E,- - '^®{bur)Depth “‘^(Shelly) a.0)Q . 3®(sh«ilyl
®(shelly) 876-696
2 —- ^(shelly)
yrs. B.P.
®(mas)
^(shelly)
- 4-b ®(»h«lly)
OCR-05-S112 Rodln-05-VC1
Core Core
RLBF LF Log G.RR P.l. 0 LF Log G.RR Rl.
S(rtd)
^(mas)
S(rtd)
1 -
9®(shelly)
®(lam)
£
^ 2
Q. ^(shelly)
^(lam)
^(shelly)
.145-103
yrs. BP.
199-141
yrs. B.R
Oreln-06-VC1 Oreln-06-VC2
Core Core
LF Log G.P.R
S(rtd)
SP
S,dd,
^(bur/rtd) ^91-221
^(mas) cal. yrs. B.P.
-
S(bur)
S(rtd)
S(bur)
^(mas) 676-524
^(m»s) 1
M/S yrs. B.P.
^(bur) 1526-1356
cal.
'^S,bur)| yrs. B.P.
'’(mas) 1
M/S ^(mas)
^(ms5)| M/S ?«"'J
'^^(bur
— CO o S(mas) 2163-1875
^(Shelly) yrs. B.P.
Salln-05-VC1 Salln-05-VC1
Core Core
LF Log G.P.R P.l.
SalvoDUA-05-S1
Core Core
Core Core
LF G.P.R p.i.
0 1
9S{rtd)
gs/s 11
1
S(rtd)
I ? loverwasl"
9S(bur) '••f
^(lam)
^(mas)
9S, Inlet
H s:(shelly)|| Channel(lam)
Q. 9^(shelly
0)
Q S(lam)|
C!
» f
* .
i
SalvoDUA-05-S4 SalvoDUA-05-S4B
Core Core
[ F Log G.P.R RI. I F Loa G.RR PI Age
VODUA-05-S5 SalvoDUA-05-S5B
Appendix F:
Transformed Abundance Data of Foraminifera Assemblages
SatvoOUA
Kinnln-05- Kinnln-05- Klnnln-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- OCR-05- Oreln-06- 05-S3B Salln-05-
SI 288- VC1 155- VC2 209- S108 281- SI08 309- S108 416- S108 445- S109 203- S109 505- S110 151- S110 304- S110 475- S111 151- Sill 320- S112 116- S112 275- VC1 132- 317-318 VC1 503-
289 cm 156 cm 210 cm 282 cm 310 cm 417 cm 446 cm 204 cm 506 cm 152 cm 305 cm 476 cm 152 cm 321 cm 117 cm 276 cm 133 cm cm 504 cm
Ammonia parkinsoniana 0.935085 0.612555 0.5411 0.580724 0.595342 0 0 0.37575 0.612555 0 0.391 0.420111 0 0 0.373559 0.336076 0 0 0.583189
Asterioerina cannata 0 0 0 0.128124 0 0.475882 0 0.216086 0 0.387317 0.158777 0.170458 0 0.485128 0 0 0 0 0
Buccella inusitata 0.224075 0 0 0.287286 0 0.679674 0 0 0 0 0.224782 0.208894 0 0 0 0.290705 0 0 0.257843
Cibicides lobatulus 0 0 0 0.287286 0.169536 0.475882 0 0.306192 0 0.551286 0.391 0.319873 0 0.56207 0.761013 0.290705 0 0 0
Elphktium excavatum 2.009758 2.529038 2.179042 1.939767 2.354762 1.110242 1.910633 1.927126 2.529038 1.910633 1.924007 1.964984 0 1.883563 1.255241 2.074323 2.619278 2.394008 2.005881
Elphidium qatvestonense 0.436469 0 0 0.314925 0.268546 0.475882 0.522315 0.306192 0 0.88972 0.224782 0.342169 0 0.806114 0.654909 0.167444 0 0.522315 0.744337
Elphidium aunteri 0.193953 0 0 0.18132 0 0.475882 0 0.216086 0 0.387317 0.158777 0.120459 0 0.278247 0 0.376193 0 0 0
Elphidium macellum 0 0 0 0 0 0 0 0 0 0 0.158777 0.120459 0 0 0 0.167444 0 0 0
Bphidium mexicanum 0 0 0.239619 0.517917 0 0.475882 0 0 0 0 0.318566 0.295963 0 0 0.654909 0.23708 0 0 0.18207
Bphidium sp. 0 0 0 0 0 0 0 0 0 0 0 0.208894 0 0 0.373559 0 0 0 0
Elphidium subarcticum 0.111862 0 0.239619 0.18132 0 0 0 0 0 0 0 0.208894 0 0 0.373559 0.290705 0 0 0.18207
Eponides répandus 0 0 0 0 0 0 0 0 0 0 0.158777 0 0 0 0.531458 0 0 0 0
Eponkles sp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.373559 0 0 0 0
Hanzawaia strattoni 0.224075 0 0.482766 0.427907 0.119809 0.679674 0 0.306192 0 0 0.480438 0.45434 0 0 0 0.412594 0.522315 0.522315 0.36567
Haplophraamoides sp. 0 0 0 0 0 0 0 0 0 0 0 0 0.334896 0 0 0 0 0 0
Haplophraamoides wilberti 0 0 0 0 0 0 0.522315 0 0 0 0 0 0.763786 0 0 0 0 0 0
Haynesina germánica 0 0 0 0.256779 0.36117 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Indeterminate rotatiid 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.167444 0 0 0
Nonionella atlántica 0 0 0 0.128124 0 0 0 0.37575 0 0 0.224782 0.295963 0 0.278247 0 0 0 0 0.18207
Quinqueloculina jugosa 0 0 0 0 0 0.475882 0 0 0 0 0.158777 0 0 0 0 0.167444 0 0 0
Quinqueloculina lamarckiana 0 0 0 0 0 0 0 0 0 0 0.391 0 0 0 0 0.167444 0 0 0
QuifHjueloculina seminula 0 0 0.417055 0.287286 0 0.679674 0 0.830619 0 0 0.506982 0.530965 0 0.278247 0.654909 0,412594 0 0 0
Quinqueloculina sp. 0 0 0.239619 0 0 0.475882 0 0 0 0 0 0 0 0 0 0 0 0 0
Trochammina inffata 0 0 0 0 0 0 0.927295 0 0 0 0 0 2.300524 0 0 0 0 0 0