Post on 19-Dec-2021
Ground Penetrating Radar (GPR) Investigations at the Jesup
Railroad Depot, Wayne County, Georgia
GDOT Project CSMSL-0008-00(691)
PI# 0008691
Prepared for:
Cypress Cultural Consultants, LLC
41 Sherman Drive
Beaufort, South Carolina 29907
And:
Bron Cleveland Associates, Inc.
16-B Lenox Pointe, N.E.
Atlanta, Georgia 30324
By:
Sara H. Gale
____________________________
Principal Investigator
Georgia Department of Transportation
Office of Environment/Location
3993 Aviation Circle
Atlanta, Georgia 30336
October 27, 2008
ii
ABSTRACT
On July 30, 2008, staff archaeologists from the Georgia Department of Transportation
(GDOT) conducted a series of ground penetrating radar (GPR) assessments of selected
areas surrounding the Jesup Railroad Depot, in Wayne County, Georgia. This work was
completed as part of the assessment of Site 9WY93 for Cypress Cultural Consultants,
LLC, the Consultant, and Bron Cleveland Associates, Inc (BCA).
The City of Jesup, working with BCA and GDOT, is planning to rehabilitate the railroad
depot in Jesup. The rehabilitation will include repaving the parking lot, providing
landscaping, restoring the exterior of the depot, repairing and restoring the interior, and
re-roofing the existing roof. This geophysical survey is part of the environmental impact
analysis being completed prior to the start of the rehabilitation project.
The primary focus of this work was to identify the horizontal and vertical extent of site
9WY93 and any associated features. Approximate depths of these features were
determined to aid in the evaluation of impacts from the portion of the proposed project
that will repave the parking lot. Repaving will involve removing the existing asphalt,
regrading as necessary, and repaving the lot. The regrading process has the potential to
impact approximately 30 cm below the ground surface.
Results from this survey were utilized to verify the location of several buried utilities and
identify an old entrance or pull-through for the depot, possible former tree locations, and
several other anomalies. None of these features will be adversely impacted by the
rehabilitation project, including the repaving or regrading of the parking lot.
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TABLE OF CONTENTS
Page
Abstract ............................................................................................................................... ii
List of Figures .................................................................................................................... iv
List of Tables .......................................................................................................................v
Introduction ..........................................................................................................................1
Methods................................................................................................................................3
Results and Interpretations ...................................................................................................7
Conclusions and Recommendations ..................................................................................17
References Cited ................................................................................................................19
iv
LIST OF FIGURES
Figure Page
Figure 1. Location of GPR survey grids adjacent to the Jesup Railroad Depot. ................ 2
Figure 2: GSSI SIR-3000 GPR unit with attached 400 MHz antennae. ............................. 5
Figure 3. Sketch map of grid layout around the Jesup Railroad Depot. ............................. 6
Figure 4: Amplitude Slice-Maps for Grids 1, 2, & 3. ......................................................... 8
Figure 5: GPR profile 2 from Grid 1. ................................................................................. 9
Figure 6: Feature 1, railroad tracks visible on the ground surface. ..................................... 9
Figure 7: Railroad track spur visible on the ground surface and located within Grid 1. .. 10
Figure 8: Linear utility features. ....................................................................................... 10
Figure 9: Photograph of Grid 2 facing northwest. ............................................................ 11
Figure 10: Parking lot where Grids 4 & 5 were located. .................................................. 11
Figure 11: Amplitude Slice-Maps for Grids 4 & 5. .......................................................... 12
Figure 12: Feature 2, former depot entrance. .................................................................... 13
Figure 13: Aerial Photograph of a portion of downtown Jesup taken in 1959. ................ 14
Figure 14: GPR profile 48 from Grid 4. ........................................................................... 15
Figure 15: Feature 3, possible historic tree location. ........................................................ 15
Figure 16: GPR profile 50 from Grid 4 ............................................................................ 16
Figure 17: Water line ........................................................................................................ 16
Figure 18: Location of features visible in the GPR data. .................................................. 17
v
LIST OF TABLES
Table Page
1. Summary Information for GPR Grids..............................................................................5
1
INTRODUCTION
On July 30, 2008, staff archaeologists from the Georgia Department of Transportation (GDOT)
conducted a series of ground penetrating radar (GPR) assessments of selected areas surrounding
the Jesup Railroad Depot, in Wayne County, Georgia (Figure 1). This work was completed as
part of the assessment of site 9WY93 for Cypress Cultural Consultants, LLC., the Consultant,
and Bron Cleveland Associates, Inc (BCA).
The City of Jesup, working with BCA and GDOT, is planning to rehabilitate the railroad depot in
Jesup. This geophysical survey is part of the environmental impact analysis being completed
prior to the start of the rehabilitation project. GDOT personnel who helped with the geophysical
survey on this project included Sara Gale and Heather Mustonen. Two other GDOT employees
from the Testing Management District 5 Laboratory, David Graham and Kevin Leonard, also
helped with the July revisit to site 9WY93.
A Phase I archaeological survey was conducted by Cypress Cultural Consultants, LLC. on
March 14, 2008. This survey identified the entire APE of the rehabilitation project as site
9WY93, which is associated with the historic train depot and contains a mid-nineteenth century
residential component (Owens 2008:29). During this initial survey shovel test pits could only be
dug in areas that were not paved or covered with compact gravel. In order to identify features
beneath the paved area a geophysical survey and additional shovel test pits was determined
necessary to complete the assessment of site 9WY93. The geophysical survey was conducted by
GDOT archaeologists and the shovel test pits were completed by the Consultant with the help of
the GDOT Testing Management District 5 Laboratory.
Interpretations in this report were guided by previously identified features associated with the
depot in both a historic and modern context. Vertical locations of features identified from the
geophysical data are of great importance for the purposes of this work. Features located at least
30 cm below the ground surface (cmbs) do not have the potential to be impacted by the Jesup
Railroad Depot rehabilitation project since they are not within the vertical area of potential effect
of the project. Ground disturbing activities are supposed to be minimal and only extend to
approximately 30 cmbs. Therefore any features located within the first 30 cmbs have the
potential to be impacted by the project and features located deeper than 30 cmbs do not have the
potential to be impacted by the project.
2
Figure 1. Location of GPR survey grids adjacent to the Jesup Railroad Depot.
3
METHODS
Ground penetrating radar data are acquired by transmitting pulses of electromagnetic energy
waves into the ground from a surface antenna, reflecting the energy off buried objects, features,
or bedding contacts and then detecting the reflected waves back at the ground surface with a
receiving antenna. When collecting radar data, surface antennae are moved along the ground in
transects, typically within a surveyed grid. A large number of subsurface reflections are collected
along each line. As energy waves move through various subsurface materials, the velocity of the
waves will change depending on the physical and chemical properties of the material through
which they are traveling (Conyers 2004). The greater the contrast in the physical and chemical
properties between two materials at an interface, the stronger the reflected signal, also called
amplitude, will appear (Conyers 2004). When travel times of energy pulses are measured, and
their velocity through the ground is known, distance (or depth in the ground) can be accurately
measured (Conyers 2006). Each time a radar wave passes through a material with a different
physical or chemical property, the velocity will change and a portion of the energy wave will
reflect back to the surface and be recorded. The remaining energy will continue to pass into the
ground to be further reflected, until it finally dissipates with depth.
Depths to which radar energy can penetrate, and the amount of resolution that can be expected in
the subsurface, are partially controlled by the frequency (and therefore the wavelength) of the
radar energy transmitted (Conyers 2004). Standard GPR antennae propagate radar energy that
varies in frequency from about 10 megahertz (MHz) to 1000 MHz. Low frequency antennae
(10-120 MHz) generate long wavelength radar energy that can penetrate up to 50m in certain
conditions, but are capable of resolving only very large buried features. In contrast, the
maximum depth of penetration of a 900 MHz antenna is about one meter or less in typical
materials, but its generated reflections can resolve features with a maximum dimension of a few
centimeters. A trade off therefore exists between depth of penetration and subsurface resolution.
In this survey a 400 MHz antenna was used, which produced data of good resolution up to
approximately 2.75-3 meters below the ground surface. Below this depth, extraneous
background noise affected the signal, making resolution of any features difficult.
Success of GPR surveys in archaeology is largely dependent on soil and sediment mineralogy,
clay content, ground moisture, depth of burial, and surface topography and vegetation.
Electrically conductive or highly magnetic materials will quickly attenuate radar energy and
prevent its transmission to depth. The best conditions for energy propagation are therefore dry
sediments and soil, especially those without an abundance of clay. The soils at 9WY93 consist
of approximately Ona and Blandon sands, which are poorly to moderately well drained sands
underlain by sand subsoil (USDA soils series descriptions 2008). An abundance of sand should
therefore allow for good energy propagation.
The “time window” within which data were gathered was 50 nanoseconds (ns). This is the time
during which the system is “listening” for returning reflections from within the ground. The
greater the time window, the deeper the system can potentially record reflections. In this survey,
50 ns is equivalent to about 2.75 m in real depth. To convert time in nanoseconds to depth, it
was necessary to determine the elapsed time it took the radar energy to be transmitted, reflected,
4
and recorded back at the surface. This amount of time is estimated by the post-processing
software RADAN. All profiles and processed maps were then converted from time in ns to
depth in meters using this average velocity.
How well the antenna stays in contact with the ground surface will also affect the quality of data
collected. A good antenna coupling means that there is a consistent distance between the bottom
of the antennae and the ground surface. Since an antenna can never be completely flush with the
ground surface, a consistent distance may be removed from the reflection profiles during data
processing to improve depth interpretations. A smooth paved parking lot is one of the best
scenarios for obtaining good antenna coupling. The paved areas surrounding the Jesup Railroad
Depot are not entirely smooth, but still allowed for an overall good antenna coupling during data
collection. During data processing a total of 3.71 ns were removed from all reflection profiles as
the distance from the antenna to the ground surface.
The initial data processing involved the generation of amplitude slice-maps (Conyers 2004).
Amplitude slice-maps are a three-dimensional tool for viewing differences in reflected
amplitudes across a given surface at various depths. Reflected radar amplitudes are of interest
because they measure the degree of physical and chemical differences in the buried materials.
Strong, or high, amplitude reflections often indicate denser buried materials, such as cultural
features. Amplitude slice-maps are generated through the comparison of reflected amplitudes at
the same depth across all of the raw vertical profiles. The amplitudes of all traces are compared to
the amplitudes of all nearby traces along that profile and between surrounding profiles. This
database of amplitude reflections can then be “sliced” horizontally and displayed to show the
variation in reflection amplitudes at a sequence of depths in the ground. The produced image is a
map that shows changes in amplitudes at a given depth in plan-view. Often when this is done
changes in the subsurface related to disturbances such as the backfilled areas or middens can
become visible.
Slicing of the data generally begins with the reversal of even numbered profiles, to compensate
for the data collection technique. This is needed because the data are collected in transects that
move back and forth to create a grid. Since every other line is collected in the opposite direction,
reversal is necessary prior to mapping the data. Following this step filters are applied to the raw
profiles to remove background noise and other wavelengths that might interfere with the
visibility of the wavelengths reflecting off of buried cultural features. The final step is generating
amplitude slice-maps. Those slice-maps are a series of x,y,z values, with x and y being the
location on the surface within each grid and z being the amplitude of the reflected waves at each
depth in the ground. All of the processing to this point takes place using the GSSI software
RADAN 5.0. Only once the slices are created in RADAN 5.0 can they be exported to a mapping
software, such as Surfer.
From the original .dzt files (raw data), a series of image files were created for cross-referencing
to the amplitude slice-maps that were produced. Two-dimensional reflection profiles are
analyzed to determine validity of the features identified on the amplitude slice-maps. The
reflection profiles show the geometry of the more continuous reflections, which can lend insight
into whether the radar energy is reflecting from a flat layer (seen as a distinct band on profile)
versus a single object or wall (seen as a hyperbola in profile). Using these profiles to confirm or
5
refute ideas about the nature of buried materials seen in the three-dimensional slice-maps,
features of potential cultural significance were delineated.
The GPR data were collected using the GSSI SIR-3000 unit with an attached 400 MHz antenna
(Figure 2). Transects were spaced every 50 cm, which is the approximate width of this antenna.
Transects started in the southwest corner of the grid and were collected in a zig-zag pattern on a
north-south orientation across the grid. The placement of the first transect in the southwest
corner allows for easier processing using RADAN.
Figure 2: GSSI SIR-3000 GPR unit with attached 400 MHz antennae.
GPR data collection works best using a grid format. For the purposes of this survey five separate
grids were set-up surrounding the railroad depot on the eastern, southern, and western sides
(Figure 3). The size of each grid was modified to fit within the area of potential effect (APE). A
total of 1218 square meters were surveyed for this project (Table 1).
Table 1. Summary Information for GPR Grids.
Grid X-length (m) Y-length (m) Area (m2)
1 5 30 150
2 12 4 48
3 5 24 120
4 15 30 450
5 15 30 450
Total 1218
The primary advantage and use of RADAN is its ability to process GPR data in 3D, although it
also has other significant features such as removal of background noise, the application of
different filters, and calculation of radar velocity through the ground. Once a 3D image was
generated in RADAN for each grid, we then created time slices at regular depths and exported
them to Surfer for additional processing. Surfer works very well at manipulating files containing
6
X,Y, and Z coordinates. Once in Surfer, each grid was analyzed individually. For consistency,
each grid was sliced at 20 cm intervals from the surface to approximately 160 cm. In a few cases
where radar readings and field conditions were particularly good, and/or there were targets, we
continued slicing up to 2 m. We could then change color values to amplify high reflectivity
targets. Surfer also allows for multiple time slice images to be displayed side-by-side and stacked
vertically for better interpretive results.
Figure 3. Sketch map of grid layout around the Jesup Railroad Depot.
7
RESULTS AND INTERPRETATIONS
Results from the survey indicate several anomalies that could be associated with Site 9WY93.
Several linear reflections were also identified during this survey and determined to be associated
with buried utilities. An employee with the City of Jesup verified the location of several buried
utilities prior to cutting holes in the asphalt and digging additional shovel test pits beneath the
parking lot. The employee’s information corresponded with utility features visible in the GPR
data.
Data were interpreted using both GPR profiles and amplitude slice-maps. Particular attention
was given to the depths of reflected features. High amplitude reflections that occurred from 0-30
cmbs could represent features that might be impacted by the milling and repaving of the parking
lot. Deeper features, 30+ cmbs, will not be impacted by the current construction plans.
Therefore, even if deeply buried high amplitude reflections indicate features associated with the
Jesup Railroad Depot additional testing may not be recommended as these features will not be
impacted by the rehabilitation project.
Grids 1-3
Grids 1 and 3 were placed on the eastern side of the depot building, while Grid 2 was placed to
the south of the depot building (Figure 3). These three grids were all based upon the same datum
point in the southwest corner of Grid 2. This allowed for all three of the grids to be processed
together in RADAN. In total Grids 1-3 measured 318 square meters. The entire area was paved,
which provided for very good antennae coupling with the ground surface during the survey. Only
a few locations, such as the railroad tracks and places where the pavement had been patched,
caused minimal uncoupling of the antennae with the ground surface.
8
Figure 4: Amplitude Slice-Maps for Grids 1, 2, & 3.
Only one feature, an abandoned portion of a railroad track spur (Feature 1), was visible on the
ground surface. This portion of railroad track was located in the northwest quadrant of Grid 1
and was highly visible in both the GPR amplitude slice-maps (Figure 4) and reflection profiles.
The surface condition of the railroad tracks indicates that any remaining components of the
feature have been encased in concrete. Encasement likely occurred once the portion of track was
out of use and the entire area surrounding the depot was paved for a depot parking and staging
area.
Figure 6
Figure 8
9
Figure 5: GPR profile 2 from Grid 1.
The railroad crossties appear in GPR reflection profile 2 from Grid 1 (Figure 5) as regularly
spaced hyperbolas, which extend from the northern edge of the grid 22 meters to the south.
These hyperbolas are seen in the amplitude slice-maps as evenly spaced lines oriented
approximately east-west. The crossties are especially visible in the slice that averages the
amplitude of reflections between 25-50 cmbs (Figure 6).
Figure 6: Feature 1, railroad tracks visible on the ground surface.
Results from the GPR survey over the railroad track spur indicate that much of the subsurface
structure of the tracks is still intact, but encased in concrete. Crossties can be seen in both the
amplitude slice-maps and reflection profiles. Feature 1, located east of the Jesup Railroad Depot,
is within the project’s area of potential effect. No construction activities are proposed for this
side of the depot as part of the project to rehabilitate the depot and repave the parking lot. Based
upon the track and crosstie encasement in concrete and the current design plans for the
rehabilitation project no additional testing is recommended for this feature.
Crossties
22 meters
N
10
Figure 7: Railroad track spur visible on the ground surface and located within Grid 1.
South of the depot is another paved area. An employee of the City of Jesup indicated that this
area had the potential to house an underground utility line. Two such lines were identified in the
amplitude slice-maps between 0 and 100 cmbs (Figure 8). These lines, annotated in Figure 8,
connect the southern side of the depot with utilities located outside of the survey area.
Figure 8: Linear utility features.
Neither Grid 2 nor Grid 3 contained any apparent features historically associated with the depot.
Utility lines identified in the GPR data are associated with the modern depot as indicated by the
employee of the City of Jesup, their shallow depth, and an associated above ground feature
(Figure 9). Based upon interpretations of the GPR data no additional testing is recommended for
this portion of the parking lot.
Utilities
11
Figure 9: Photograph of Grid 2 facing northwest.
Grids 4 & 5
Grids 4 and 5 were located to the west of the Jesup Railroad Depot building in the main portion
of the parking lot (Figure 3). Both grids measured 30 meters north-south and 15 meters east-west
for a total of 900 square meters. This encompassed almost the entire paved area to the west of the
depot building. However, a narrow section, 5 meters or less in width, adjacent to the building
was not included in either of these grids. Shovel test pits were already dug in this area during the
original Phase I archaeological survey completed by the Consultant. Since the grids were placed
next to one another with a shared datum in the southwest corner of Grid 4 and the northwest
corner of Grid 5 they could be processed together in RADAN.
Figure 10: Parking lot where Grids 4 & 5 were located.
As with Grids 1-3 the entire survey area in Grids 4 and 5 was paved. Good antenna coupling was
facilitated by the relative smoothness of the paved surface. Some sections had been disturbed by
various methods used to patch holes and facilitate repairs in the parking lot (Figure 10). These
Utility feature
12
areas were easy to pull the antenna over and did not have a significant impact on the depth
interpretation for the GPR data.
Figure 11: Amplitude Slice-Maps for Grids 4 and 5.
Several anomalies were identified within Grids 4 and 5, including utility lines, a former depot
entrance, possible old tree locations, and unidentifiable features potentially associated with the
depot or an earlier occupation of the site. Figure 11 shows all of the amplitude slice-maps for the
composite of Grids 4 and 5. Areas of interest are outlined and described in detail below. These
areas are where anomalies were the most apparent. In total 3 anomalies are interpreted based
upon their possible association with site 9WY93. Of these anomalies two are considered to be
potential features associated with the depot and the other anomaly is a water line. As with Grids
1-3 the depth of each anomaly in Grids 4 and 5 is emphasized. Any feature located deeper than
30 cmbs does not have the potential to be impacted by repaving of the parking lot.
Figure 12
Figure 17
Figure 15
13
Figure 12: Feature 2, former depot entrance.
A highly reflective crescent-shaped feature is visible in Grids 4 and 5 and between 0-275 cmbs.
The feature is visible in reflection profiles and amplitude slice-maps from both grids. However,
the geometry of the crescent-shaped feature is more readily visible in the amplitude slice-maps,
outlined in Figure 12 with a solid red line. The GDOT has an archive of aerial photography from
their projects. This archive was searched for photographs that might show changes in the use of
the area surrounding the depot. The earliest aerial photograph available through GDOT for the
City of Jesup was created on October 19, 1959 (Figure 13). A crescent-shaped grassed area
appears in this photograph to the west of the depot building (Figure 13A). This grassed area
indicates that the rectangular parking lot now located to the west of the building was not in use in
1959. Instead a pull-through entrance was used to direct traffic in and out of the depot. There is
no evidence that the American Stick Style depot, which predated the present structure (Caldwell
2001:203), used the same entrance as the pull-through seen in the 1959 aerial photograph.
However, the aerial photograph does indicate that the pull-through was part of the historic depot
built sometime following 1900.
Profile 48
14
Figure 13: Aerial Photograph of a portion of downtown Jesup taken in 1959.
The high amplitude crescent-shaped reflection was possibly created by years of differential water
seepage between the grassed area and the paved pull-through. Profile 48 from Grid 4 shows the
layer just below the ground surface (Figure 14). Because the pull-through layer is located at such
a shallow depth it has likely been consolidated with the paved parking lot placed atop it. A
shovel test pit may indicate a difference in material used to construct the two paved surfaces, but
information on horizontal shape is more readily defined through the use of aerial photography
and geophysical data. Therefore through these methods more is known about this feature than
could be determined through shovel testing or even test excavation units. It remains to be seen
whether or not any differentiation is possible between the paving of the pull-through and that of
the parking lot. Due to the amount of information already gained from aerial photography and
geophysical analysis no additional testing is recommended. Repaving of the parking lot may
impact the pull-through layer. However, this layer has already been impacted by prior paving of
the parking lot and therefore would not be an adverse impact.
A B
15
Figure 14: GPR profile 48 from Grid 4.
Geophysical interpretations of another group of reflections were enhanced through the use of the
1959 aerial photograph. Feature 3 appeared on the northern edge of Grid 4 in amplitude slice-
maps between 150-200 cmbs (Figure 15). The aerial photograph of the City of Jesup also shows
one tree located in approximately the same location (Figure 13B).
Figure 15: Feature 3, possible historic tree location.
In Profiles 43 - 51 from Grid 4 the last 3 meters of each profile show areas where the sandy
subsurface is disturbed (Figure 16). Part of Feature 3 is obscured by a shallower hyperbolic
reflection, described below, located approximately 100 cmbs (Figures 11 & 16). When the tree
was removed from the depot’s landscaping it is unlikely that the entire root mass was also
removed. The organic remnants of the tree would have a high contrast to the natural sandy
subsurface beneath the parking lot. Throughout all the reflection profiles from Grids 4 and 5
Feature 3 appears to be the most distinct from the surrounding soil matrix. Anomalies located in
primarily sandy soils should be visible as high contrast reflections. The overall lack of high
N
42-53
Meters
16
amplitude reflections in the GPR data from Grids 4 and 5 made the area defined as Feature 3
significant.
Figure 16: GPR profile 50 from Grid 4
A water drainage pipe was placed on top of Feature 3 sometime after the reflective surface was
created. The pipe appears in the reflection profiles as a very distinct hyperbola, the apex of which
is located at approximately 100 cmbs (Figure 16). This modern intrusion has likely compromised
the integrity of the reflective surface identified as Feature 3. Although there is no visual
confirmation of the feature, it is outside of the project’s vertical area of potential effect.
Therefore no additional testing is recommended for this feature.
Figure 17: Water line
As described above a water line was intrusive in both Grids 4 and 5. The water line is visible in
almost all of the amplitude slice-maps as linear reflective surfaces. These surfaces are marked in
Figure 17 with a black line and are located along the northern edge of Grid 4, the eastern edge of
Grids 4 and 5, and running east-west at approximately 23 m north in Grid 5 (Figure 11 & 16).
Since these reflections were identified as water utility lines no additional testing is recommended
for these anomalies.
N
27-30
Meters
17
CONCLUSIONS AND RECOMMENDATIONS
A geophysical survey using ground penetrating radar was incorporated into the analysis of
9WY93, the Jesup Railroad Depot, to ensure that potential impacts to any features associated
with the site, but buried under a paved parking lot, were assessed. Five GPR grids were placed
around the depot building almost entirely covering the paved surfaces. Results from this survey
identified five anomalies, three of which are proposed to be associated with the depot (Figure
18).
Figure 18: Location of features visible in the GPR data.
Two of the anomalies identified were associated with modern utility work at the site. Utility lines
were visible in both the amplitude slice-maps and the reflection profiles as linear high amplitude
reflections and distinct hyperbolas. A worker for the City of Jesup identified all of these utilities
prior to the survey. Although these anomalies are not associated with site 9WY93 they are
outside of the project’s vertical area of potential effect, 30+ cmbs or deeper.
18
Feature 1, a railroad track spur, was visible on the ground surface and easily associated with the
depot. The tracks and their crossties were visible in both the amplitude slice-maps and reflection
profiles. Both above-ground and subsurface evidence indicate that the tracks have been encased
in concrete as part of paving the parking lot in the past. As the integrity of this feature has
already been impacted by past paving and the feature is located outside of the current project’s
area of potential effect, no additional testing is recommended for the railroad track spur feature.
The second feature was located in Grids 4 and 5 and was visible as a crescent-shaped highly
reflective layer in the amplitude slice-maps and reflection profiles from 0-275 cmbs. A former
paved pull-through entrance was identified in an aerial photograph of downtown Jesup taken in
1959. The aerial photograph confirmed that the crescent-shaped Feature 2 was associated with
depot at least 49 years ago. This feature is however located just below the ground surface and has
been paved over by the current parking lot. Additional testing of this feature is not likely to yield
any additional information than what has already been discussed. Therefore no additional testing
of this feature is recommended for the pull-through entrance.
Feature 3 was located in Grid 4 and is the most ephemeral of the three features. At a depth of
approximately 150 - 200 cmbs a disturbance can be seen in the amplitude slice-maps and the
reflection profiles. Based upon aerial photography evidence this feature could be associated with
a tree that was part of the depot’s landscaping in 1959. The root mass from the tree may not have
been removed with the tree thus leaving behind organic remains in sandy soil, which would
create a strong contrast for electromagnetic energy to be reflected off of. This feature is located
outside of the project’s vertical area of potential effect and therefore does not warrant additional
testing.
Based upon the geophysical data collected during July 2008, several features were identified that
are potentially associated with the Jesup Railroad Depot, 9WY93. However, all of these features
have either already been negatively impacted by paving of the parking lot or are outside of the
project’s area of potential effect. Therefore no additional testing is recommended for the three
features identified during this survey.
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REFERENCES CITED
Owens, Daphne L.
2008 An Archaeological Survey in Anticipation of the Rehabilitation of the Jesup Railroad
Depot, Wayne County, Georgia. Cypress Cultural Consultants, LLC. Submitted to the
Georgia Department of Transportation, Project CSMSL-0008-00(691), PI# 0008691.
Copies available from the Georgia Department of Transportation.
Caldwell, Wilber W.
2001 The Courthouse and the Depot: The Architecture of Hope in the Age of Despair. Mercer
University Press, Macon, Georgia.
Conyers, Lawrence B.
2006 Innovative Ground-penetrating Radar Methods for Archaeological Mapping.
Archaeological Prospection 13:137-139.
2004 Ground-penetrating Radar for Archaeology. Altamira Press, Walnut Creek, California.
Soil Survey Staff
2008 Natural Resources Conservation Service, United States Department of Agriculture.
Official Soil Series Descriptions electronic document,
http://soils.usda.gov/technical/classification/osd/index.html, Accessed August 21, 2008.