Geophysical Survey Tuscumbia Landing

Sheffield, Alabama

Kent A. Schneider, Ph.D. Douglas Luepke

Matthew McMillen

DRAFT 5/27/2010  

 

 

 

 

 

May 27, 2010

Bucks Geophysical Corporation Plumsteadville, PA

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Contents Page Introduction 5 Site Conditions 5 Site Grid 6 Geophysical Tools and Results 7 Figure 1. Geophysical Coverage Map 7 1. Electromagnetic (EM) Data 8 1a. About EM 8 1b. Results 8 Figure 2. Conductivity Contour Map 9 2. Magnetometer/Gradiometer 9 2a. About Magnetometer/Gradiometer 9 2b. Results. 10 Figure 3. Magnetic Contour Map 10 Figure 4. Magnetic Gradient Contour Map 11 2.b.1. Interpretation of Electromagnetic and Magnetic Survey 11 Figure 5. Electromagnetic and Magnetic Interpretation 12 3. Ground Penetrating Radar (GPR) 12 3.a. About GPR 12 3.a.1. Depth of Penetration 13 Figure 6. Depth Measurement 14 Table 1. Time Window and Estimated Depth 15 3.a.2. Radargram Signal Processing 15 3.a.3 Time Slice Processing 16 3.b. Results 16 Figure 7. GPR Interpretation 17 Figure 8. GPR Grids at Tuscumbia Landing 18 3.b.1 Railroad Bed 18 Figure 9. Railroad Bed slices 1-10 unmarked 19 Figure 10. Railroad Bed slices 11-20 unmarked 19 Table 2. XYZ locations of anomalies marked in Figure 10 20 Figure 11. Railroad Bed, slices 11-20 unmarked 21 Figure 12. Railroad Bed, slices 11-20 marked 21 Table 3. XYZ locations of anomalies marked in Figure 11 22 3.b.2. Possible Grave Area 22 Figure 13. Possible grave anomalies marked (Slice 1) 23 Table 4. XYZ points, possible graves 23 Figure 14. Grave area, graves not marked (Slice 1) 24 3.b.3 Grave Area Extension 25 Figure 15. Grave area extension, anomalies not marked 25

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Table 5. Anomalies and their XYZ locations, 25 Grave Extension Area Figure 16. Grave Area extension, anomalies marked 26 3.b.4 Pavilion 26 Figure 17. Pavilion, XYZ unmarked. Note foundation, Pav 2-6 27 Figure 18. Pavilion XYZ anomalies marked, note Pav 5, 11 28 Table 6. Pavilion XYZ anomaly locations 28 3.b.5 Visitor Center 29 Figure 19. Visitor Center, XYZ anomalies not marked 29 Figure 20. Visitor Center, XYZ anomalies not marked 30 Table 7. XYZ locations for Visitor Center anomalies 31 3.b.6. Nitrate Plant 31 Table 8. XYZ points for possible pipes, Nitrate Plant 31 Figure 21. Nitrate plant, 20 slices unmarked 32 Figure 22. XYZ points for possible pipes, Nitrate Plant 32 4. Mapping 33 Figure 23. Feature Data 33 Figure 24. Georeferenced Geophysical Data 34 Conclusions 34

Appendix I Photos, Figures, and Tables Photo 1. Heavily vegetated Tuscumbia Landing 2 Photo 2. Tuscumbia Landing after vegetation removal, clean up 3 Figure 1. Geophysical Coverage Map 4 Figure 2. Conductivity Map 5 Figure 3. Magnetic Map 6 Figure 4. Gradient Map 7 Figure 5. Electromagnetic and magnetic survey interpretation 8 Figure 6. Depth Measurement calculation 9 Figure 7. GPR Interpretation 10 Figure 8. GPR Grids at Tuscumbia Landing 11 Figure 9. Rail road bed slices 1-10 unmarked 12 Figure 10. Rail road bed Slices 1-10, marked 13 Figure 11. Rail road bed, Slices 11-20 unmarked 15 Figure 12. Rail Road bed, slices 11-20 marked 16 Figure 13. Possible grave anomalies, Slice 1. 18 Figure 14. Grave area, graves not marked (Slice 1) 20 Figure 15. Grave area extension, anomalies not mark 21 Figure 16. Grave Area extension, anomalies marked 22 Figure 17. Pavilion, XYZ unmarked. Note foundation, Pav 2-6 24 Figure 18. Pavilion XYZ anomalies marked, note Pav 5, 11 25 Figure 19. Visitor Center, XYZ anomalies not marked 27

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Figure 20. Visitor Center XYZ anomalies marked 28 Figure 21. Nitrate plant, 20 slices unmarked 30 Figure 22. XYZ points for possible pipes, Nitrate Plant 31 Figure 23. Feature data 33 Figure 24. Georeferenced geophysical data 34

Table 1. Time window and estimated depth 9 Table 2. XYZ locations of anomalies marked in Figure 9 14 Table 3. XYZ locations of anomalies marked in Figure 11 17 Table 4. XYZ points, possible graves (Figure 12) 19 Table 5. Anomalies and XYZ locations, Grave Extension Area 23 Table 6. Pavilion XYZ anomaly locations 26 Table 7. XYZ locations for Visitor Center anomalies 31 Table 8. XYZ point for possible pipes, Nitrate Plant 31

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Introduction Tuscumbia Landing is located in Colbert County and is owned by the City of Sheffield, Alabama. The site is a National Register site and is listed as a Certified Historic Site on the Trail of Tears National Historic Trail. The historical significance of Tuscumbia Landing is in part captured by the National Historic Trail citation:

Historical Significance: Tuscumbia Landing was located at the western terminus of the Tuscumbia, Courtland, and Decatur Railway. During the summer of 1838, Cherokee detachments headed by Lt. Edward Deas and Lt. R.H.K. Whiteley attempted to travel from Ross Landing, Tennessee to Fort Gibson, Indian Territory via the “water route.” These detachments floated down the Tennessee River to Decatur. Due to low water and potential difficulties navigating through Muscle Shoals, they rode on the railway west to Tuscumbia Landing and then boarded boats headed downriver. Prior to that summer, numerous other “water route” detachments brought Creeks, Choctaws, and other groups past this spot on their way to Indian Territory. Tuscumbia Landing was also the site of considerable Civil War activity.

The present Report focuses on the results of 3 geophysical techniques used to image the historical and archeological subsurface features of three transportation-related activities associated with Tuscumbia Landing during the 1800s: Railroad Bed and depot, wagon road, and steamboat landing. The physical remnants of some of these activities can be seen on the ground surface at Tuscumbia Landing today. Starting in January, 2010, Bucks Geophysical Corporation imaged buried features associated with these activities using ground penetrating radar (GPR) as the principle geophysical tool, and electromagnetics (EM) and magnetometry (MAG) as secondary tools. The results are best seen in the imagery developed from each of the geophysical tools. The authors of this report present those anomalies they believe are worth further investigations. The GPR imagery is animated, each animation being displayed as a .jpg. Users of this report are encouraged to study the animations to locate anomalies they think are worth further investigation in addition to those described by the report authors. All Photos, Figures, and Tables in this report are enlarged in Appendix I.

Site Conditions First visited in the Fall, 2008, by Schneider and Luepke, the 11 acre site was densely forested and heavily vegetated. Privet and hedge darkened the site. (Photo 1) The leaf-

out blocked ones view of the landscape while walking down a path across the spine of the site from the site entrance near a parking lot to a trail that led down slope to the Tennessee River’s edge. Ground penetrating radar (GPR), to be effective, has a data collecting antenna which must skim the ground surface or be within a few inches of it. There was no chance the GPR would be effective in surface conditions like those seen in 2008. In the Fall, 2009, a “brontosaurus” or similar brush and tree

Photo 1. Heavy Brush

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d, e site.

clearing equipment (Photo 2) cleared the site under the watchful eye of Gail King, working with Mike Johnson, Director of Parks and Recreation, City of Sheffield, Alabama, which owns Tuscumbia Landing. The brush clearing was followed up with hand clearing by Mr. Johnson’s crew, to whom we are indebted. When we arrived to begin our work in January, 2010, the ground vegetation was gone, leaving only the trees. Teams of volunteers were on hand to remove ground clutter, snags and debris that might affect antenna travel over the ground.

The geophysical team was on site January 18-23, March 1-4, and March 17-19, 2009 for a total of 13 full field work days. The team was assisted by a host of energetic volunteers who pitched in to carry equipment, run tapes, and clear the ground of fallen

debris. The days of field work activity were determined by the rainy weather. The team was ever conscious that weather conditions may affect the quality of data recovered and did not work in the rain or snow. The team allowed a minimum of 2 days to lapse before deploying equipment to allow surface water from rain or snow to soak into the well draineunfrozen soils at th

Photo 2. Site cleared

Site Grid

A geophysical grid was set up by the geophysical team as no grid had been established for Tuscumbia Landing. Using GPS and photo overlay analysis, the geophysical grid was converted to its location in space for presentation in this report. However, the report discusses anomalies found in reference to the geophysical grid as it was established on the ground.

Main baseline 500E 433598.1 m 745E 433825.1 m 500N 3845486.1 m 500N 3845569.4 m Coordinates are in NAD1983, UTM Zone 16N meters The base line for the geophysical grid is a line down the center of what was described as the “Railroad Bed”. Its hub is located at 500N, 500E which lies near the west terminus of the Railroad Bed. The baseline (500E, 500N and 745E, 500N) is tied down by three marker trees each with distance measurement to nails in each tree. An iron pin

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was put into the ground at this location after GPR, EM, and magnetometry were completed. The line runs from 500N, 500E to 500N, 745E. The extent of the geophysical grid in meters is: Most East point, 745E Most West point 396E Most South point 410N Most North point 540N The geophysical grid was laid out in 50 meter units using Keson metric tapes, corrected for accuracy with a total station by a survey crew from TVA Archaeological Research. GPS points and lines were collected using a Trimble GeoXH along the base line and at control points throughout the grid. Features such as the Nitrate Plant and possible historic building corners were recorded, as were many anomalies found by GPR. Field note books were assigned to each geophysical tool and used exclusively for data collection with that tool.

Geophysical Tools and Results

Geophysical coverage for Tuscumbia Landing is shown in Figure 1. Each of the geophysical tools used and the results are described below (see Appendix I).

Figure 1. Geophysical Coverage Map

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1. Electromagnetic (EM) Data

1a. About EM. EM (electromagnetic) data collection is a time honored geophysical technique used to measure conductivity and hence resistivity over rough or uneven surfaces. Carried off the ground and probeless, it is used in archeological contexts to detect cavities, buried foundations, and buried metal objects. EM operates by inducing eddy currents into the ground. These currents produce a secondary magnetic field which is detected by the receiver on the instrument and allows calculation of conductivity.

At Tuscumbia Landing, EM data was gathered using a single frequency (9.8KHz) Geonics EM-31 Terrain Conductivity Meter oriented in the vertical dipole mode which obtains subsurface data to an effective depth of about 4.5 meters. Data were recorded on a Model 720 digital recorder. Both conductivity data (mmhos/m) and in-phase data (parts per thousand), along with the line number, and station location were recorded at each station. Field observations were noted in a field book. EM-31 data was collected at 0.5 second intervals (approximately every 0.5 meters) along survey lines spaced 1 meter apart. The data was downloaded to a laptop computer for processing and generation of a conductivity contour map.

1b. Results.

EM data was collected on approximately 5.3 acres of the site. The conductivity contour map (Figure 2) shows areas of high and low conductivity. Areas of high conductivity, for example, the Railroad Bed at N504, E567, and adjacent to the Nitrate Plant at N469, E562, may be caused by materials that have a higher conductivity than other material in the survey area. Material such as slag, metallic fillings mixed with fill, and fill material will cause high conductivities. Additionally water lying on the surface may also cause higher conductivities. Conductivity lows, for example the Railroad Bed at N500, E587, and N506, E585, may be caused by metallic objects, pipes, manmade objects, and materials that have a lower conductivity than the surrounding material such as sand.

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Figure 2. Conductivity Contour Map

2. Magnetometer/Gradiometer

2a. About Magnetometer/Gradiometer

The earth has a large magnetic field that can be measured with a magnetometer. A magnetometer can also detect local variations in the earth’s magnetic field that may be buried manmade objects and features. If two readings are taken at each survey station, one vertically above the other, a magnetic gradient can be established thus removing the large background effect of the Earth fields. There are theromremnant and non-heat treated effects that may be measured. In high magnetically susceptible soils, the top soil may be more magnetic than its subsoil. This is because the incorporation of decomposed or burnt particles which are significantly more magnetic. Post holes, pits, and trenches may appear in magnetic data. “If a ditch has been dug in the past and subsequently silted up with humic soil a weak positive linear magnetic anomaly may be formed” (http://www.stratascan.co.uk/magnetometry.html). On the other hand, features and objects that have been subjected to high temperatures, such as brick walls, foundations, steel or clay pipes, hearths, kilns and ferrous artifacts associated with archaeology have their magnetic levels set at the last time firing and may stand out from the background magnetism (http://www.stratascan.co.uk/magnetometry.html).

Magnetic data at Tuscumbia Landing was collected using a GEM Systems GSM-19G magnetometer. The data was collected at 0.5 sec intervals (approximately every .5 meters) along survey lines spaced 1 meter apart. Data was downloaded to a laptop computer for processing and generation of a magnetic contour map.

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2b. Results.

The magnetic data is the measurement of the earth total field. Changes in the total field are caused by natural and manmade objects. Magnetic data was collected on the same survey lines as the EM data. Magnetic high and magnetic lows are present in the data for this site (Figure 3).

Magnetic highs, for example near the possible grave area at N522, E651, or in the Railroad Bed at N499, E717, are indicative of possible buried metal. Also in the northern hemisphere buried metal should appear as a high to the south of the ferrous object and a low to the north with the object centered at the inflection point.

Magnetic lows, seen in the Railroad Bed at N503, E611 and in the Pavilion area at N463, E684, may be caused by buried debris such as concrete but may also be foundations.

The gradient data is a calculated difference between two magnetic total field sensors set at a fixed distance apart. Gradient anomalies can be seen in the Railroad Bed at N504, E696 and in the Pavilion area at N460, E676 (Figure 4). These could be smaller amounts of metal, buried debris, or foundations.

Figure 3. Magnetic Contour Map

.

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Figure 4. Magnetic Gradient Contour Map

2.b.1. Interpretation of electromagnetic and magnetic survey

The electromagnetic and magnetic survey of Tuscumbia Landing (Figure 5) detected six types of anomalous areas: magnetic highs, magnetic lows, gradient anomalies, conductivity highs, conductivity lows, magnetic dipole of which buried metal is an example (N469, E609).

The areas of possible buried metal are most likely caused by buried ferrous metal. The magnetic highs may be buried metal. Magnetic lows may be caused by buried debris such as concrete or old foundations.

Magnetic gradient anomalies are areas of higher magnetic gradients and may be caused by ferrous metal or other objects (N460, E676).

Conductivity highs may be caused by materials that have a higher conductivity than other material in the survey area such as slag, metallic fillings mixed with fill, and fill material. Additionally water lying on the surface can also cause higher conductivities. Conductivity lows may be caused by metallic objects or areas of lower conductivity material such as sand or native soil.

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Figure 5. Interpretation of electromagnetic and magnetic survey

3. Ground Penetrating Radar (GPR)

3.a. About GPR

Ground penetrating radar has grown in popularity in usage on archeological sites (Conyers and Goodman, 1997:11). GPR involves the observation of the reflected component of transmitted electromagnetic waves into the subsurface. The reflections, unlike that of acoustical waves, occur at the interfaces of materials of differing electrical conductivity or permittivity. The depth of penetration for radar waves is frequency dependent and the attenuation of the radar wave in the ground is rather quick compared to that of seismic - a few meters compared to kilometers.

Since many, if not most, buried features of archeological interest are not deeply buried the GPR has utility in the search and characterization of these features. GPR is characterized as a WYSIWIG technique - what you see is what you get. The GPR output is a series of radar wavelet traces or scans produced on a chart recorder or computer screen as an antenna is pulled across the ground surface. The radar wave perturbations can directly yield reflection depth and the relative strength of the reflections such that the form and location of a buried object or feature can be ascertained rather readily. If the velocity of the radar waves can be determined then the conversion of travel-time, between the transmitter and received, of the reflected wave, can be converted to distance similar to that done in seismic studies. Indeed, the advance of processing of GPR data is done using software that was originally

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developed in the analysis of acoustical data. Mathematical protocols such as “stacking”, migration, and deconvolution are now commonly applied to GPR data in order to tease out the finest details as to stratigraphy and shape of subsurface reflectors or features.

Tuscumbia Landing was surveyed using a Geophysical Survey Systems, Inc. (GSSI) Model SIR 3000 GPR cart mounted unit composed of a digital console, cable, and a 400MHz antenna. Although the ground surface was rough in many places, this antenna allowed the operator to image near-surface detail and stress penetration. The SIR-3000 system was used in a continuous profiling mode with distances tracked by a distance encoder built into the cart. Tape measures were placed over the site grids and data was collected along the profile traverses at 32scans/sec. Spacing between parallel profiles was 1.0 m. Data was collected in the X direction (the east-west profile), incrementing north (the Y direction). XY data was collected in the initial set up stages but was not found to significantly contribute to better results. The time window was set to 50ns to provide good imagery to about 1.4 meters in depth after numerous test runs to observe signal attenuation and optimum penetration depth for the features sought. Radar profiles were acquired in forward and reverse directions between adjacent lines.

Because radar waves are subject to severe attenuation with depth and the time of travel, later arriving reflections were amplified using an exponential gain curve to maximize the dynamic range in the recorded data. Filter settings used in recording the data were set to 100 MHz for the high pass filter and 800 MHz for the low pass filter for this particular antenna. The recorded radar reflections were digitized at 512samples/scan at 16 bit resolution.

3.a.1. Depth of Penetration

The discussion in sections 3.a.1 – 3.a.3, follows a format developed in a prior report by Goodman and Schneider (Freetown Cemetery, July 2007).  In the GPR method, radar waves are recorded in a designated time window. The chosen time window, which is measured in nanoseconds, determines the depth of penetration of the radar waves. The radar waves must travel from the antenna, bounce off subsurface structures, and then eventually travel back to the receiving antenna to get recorded. The time window that is set for recording determines the depth of penetration within the ground of the microwaves provided the microwave velocity is known or discovered through data analysis.

Several methods exist for determining the velocity of microwaves within the ground. A noninvasive procedure was used for estimating the microwave velocity beneath Tuscumbia Landing. The method involves fitting curves to hyperbolic reflections recorded on the radargrams from subsurface objects. The hyperbolas for (cylindrical) objects occur because of the broad directional response function of the ground antenna. Objects that are not directly beneath the antenna get recorded as microwaves are sent over a broad range of angles. The travel times however, from objects that are recorded off to the side of an antenna take progressively longer travel times the further they are from being directly beneath the antenna. The net effect for buried point objects is to

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a

nu of

create a hyperbolic reflection pattern. The travel time from a buried object to the antenna is given by:

T = 2*sqr(x^2+z^2)/v

-where T = the two-way travel time

x = the horizontal distance to the subsurface object

z = the depth to the subsurface object

v = the microwave velocity in the ground

The shape of a graph of T versus X gives a hyperbolic reflection pattern which we can fit to determine an estimate of the velocity. When microwave velocities in the ground are very fast the hyperbolic reflection is very broad and wide; conversely, when the

velocity is very slow, the hyperbola is very narrow.

Measurements of the microwave velocity for the survey were estimated at the site. Shown in Figure 6 is a hyperbola from possible point source target. A hyperbola was fitted to this target using an option in the filteringme

Figure 6. Depth Measurement

GPR-SLICE V7.0 Software. A dielectric permittivity of 23.41, corresponding to a velocity of about 6.2cm/ns was estimated. This estimate was made using the 400 MHz antenna. Microwaves are “dispersive” which means that the microwave velocity can sometimes depend on the frequency transmitted into the ground. The GPR antenna, although it has a central frequency near 400 MHz, other energy at different frequencies are propagated into the ground. For estimating the depth of the radar reflections, however, the estimated velocity of the microwaves ignores the possibility of dispersion.

Assuming this average microwave velocity of 6.2 cm/ns for all the areas surveyed, a penetration depth is found by multiplying the recorded time window by the estimated

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microwave velocity of the soil, and dividing by 2 to account for the two-way travel time of the reflections, i.e.

Depth = Time Window x Microwave Velocity / 2

The time window used to record reflections for Tuscumbia landing was 50ns. Taking into account the 0ns offset of 4.6ns to the recording of the first ground surface reflection, the effective time window recorded was 45.4ns. The estimated depth of penetration for the survey was 141 cm (45.4ns*6.2cm/ns/2). Based on this estimated depth for the Tuscumbia Landing, the GPR survey should reach to depths beyond the cultural deposits.

A review of the depth of penetration and the recording time window for Tuscumbia Landing is given in Table 1.

Site Effective Time Window (ns) Estimated Penetration (m)

Tuscumbia Landing 45.4ns 141cm

Table 1. Time window and estimated depth

3.a.2. Radargram Signal Processing

Before the radargram data was used to construct images, signal processing on the raw radargrams was implemented. The processes applied to the recorded data are briefly described:

1) Regaining of the radargrams in post processing was implemented to account for limitation in the control unit for the SIR 3000 to apply direct gain during recording. Small adjustments were made just below the ground surface reflection for regaining.

2) DC drift removal was implemented during the radargram conversion to remove low frequency signal which cause the radar pulse to float away from the 0 line. The DC drift was removed in a time domain moving filter.

Other signal processing options are available in GPR-SLICE v7.0 Software such as background removal and bandpass filtering. These filters are generally applied in the

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event that strong line noises are seen in the radargrams. Particularly for high-conductive soils, the signal-to-noise ratios are much weaker since recorded reflections need more amplification during recording. Viewing of the entire Tuscumbia Landing data indicated that the radargrams were relatively noise free to a depth of near 1.5 meters, which was the maximum depth need for evaluation purposes for the project. For this reason, additional signal processes were not necessary to generate noise free images to the desired target depths.

3.a.3 Time Slice Processing

Radargrams represent vertical slices taken across the ground. Time slices represent horizontal slices taken across the survey area. Time slices can be used to show variations in reflected return amplitudes at various depths across a site. Time slices are found by cutting data from all the radar profiles in a specified time window and presenting the information from this slicing window in a pixel map presentation. Depending upon the time window in which the slicing is made across the parallel profiles, depth information regarding important targets can be determined.

The radar signals within the designated time window are averaged in the vertical and some averaging in the horizontal direction was used. The squared amplitude of the recorded reflected amplitudes across the time window was computed and averaged every 0.25 m along the profile direction. Overlapped time slice datasets were created for input into a 3D data volume. The overlapping process helps to create a smoother 3D volume which would be useful for during graphic and animation display of the data.

The time slices were interpolated using an inverse distance algorithm. Data within a 1.5 meter search radius were used to weight data in estimating the interpolated reflection data. In the pixel maps, the gray scale was selected to show the data. Also a color scale was applied at the request of the client. Here, brighter colors correspond to stronger reflections; darker colors represent weaker radar returns. In some cases the data are presented in either a linear, square root, or logarithm transform to delineate various features which have a large dynamic range in recorded reflection intensity. In addition, minimum and maximum thresholding was applied to the data to enhance suspected anomalies within the datasets.

The time slices are presented as depth slices by using the nominal microwave velocity of 6.2cm/ns estimated for the soils at the site. Some parts of this dataset are provided in the written portion of this report as a general overview of the site. The written report is by no means meant to replace the study of the full animation dataset that is available on CD, showing the complete 2D depth slices.

3.b. Results

A total of 12,656 linear meters of GPR data was collected during the survey . There were 16 separate grids of GPR data individually collected, processed, analyzed, and appended into the final single grid (Figure 7). GPR was not conducted on the steep slopes but was instead restricted to the relatively flat portions of the “peninsula” that

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extends from the existing parking lot west and north to the river and south to an inlet that meanders along the southern portion of Tuscumbia Landing.

Figure 7. GPR Interpretation

The GPR work was grouped into 6 “activity areas”, two of which (Pavilion, Visitor Center) reflect future activities planned for interpretation of the site (Figure 8). A seventh area, the River, produced bedrock anomalies and was not considered further. 1. Railroad Bed 2. Possible grave area 3. Grave area extension 4. Pavilion 5. Visitor Center 6. Nitrate Plant

In the discussions that follow, the reader is urged to view the GPR animation data sets to completely visualize all anomalies that appear at different depths. It is simply not possible to present all of them here. What is presented here are those anomalies that appear to be linear, curvilinear, circular, or semicircular features that may be cultural in origin. It is only through archeological testing that their true nature can be known.

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Figure 8. GPR Grids at Tuscumbia Landing

3.b.1. Railroad Bed.

Excluding the 20th century Nitrate Plant foundations, the Railroad Bed is perhaps the most well known from the historical literature at Tuscumbia Landing: “Between the town of Tuscumbia and Tuscumbia Landing, both passenger and freight cars operated on this 2.1-mile line and were horse drawn. The iron for the rails was delivered by the steamboat James Monroe. On January 13, 1832 the Tuscumbia, Courtland & Decatur Railroad was chartered (Cline 1997: 10-12). According to a personal communication with John McWilliams, the two Railroads used the same track to a point at Tuscumbia Landing, with separate tracks to the depot” (Historic Document Research….September 11, 2008) One hundred seventy seven (177) lines of GPR data at the historical location of the Railroad Bed were collected in 8 separate grids and appended to a single data set (Figure 8, Number 1). The Railroad Bed appears quite “active” in the sense that many anomalies appear that may be associated with the Nitrate Plant. Pipes, for example, run under the Railroad Bed at different places and depths. Those anomalies that the authors suggest be tested to determine their nature are shown in Figure 9 and Table 2. Because the Railroad Bed is a long (259 meters) and narrow (10 meters) data set, it is necessarily “small” when presented as a portrait image in this discussion.

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Figure 9. Railroad Bed slices 1-10 unmarked

Figure 10. Railroad Bed Slices 1-10, marked.

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map locations are marked

Table 2 ipe 1 in

__ Pipe 1

2

3

ar

s field

rBed8

19. rBed8

hree possible pipes were identified, one unknown linear feature, and an anomalous

XYZ locational information for the anomalies marked in Figure 12. One

area (1-4), one debris field (5-9), and one possible pipe (10-12) are entified.

Figure 9 presents the 2D time slice maps from levels 1 -10. Figure 10 is the sameexcept 4 anomalous areas are shown by red dots and their XYZon the map and are presented in . P Table 2 corresponds to 1-3 in Figure 10. Pipe 2 corresponds to 4-6 in Figure 10 and so on.

# Time Slice X Y Depth-cm Comme______

nt _______________________________________________________

rBed2.grd 520.53 496.65 6.96-18.47 1. 2. rBed2.grd 515.6 502.13 6.96-18.47 3. rBed2.grd 511.9 507. 6.96-18.47 4. rBed2.grd 553.83 496.65 6.96-18.47 Pipe

5. rBed2.grd 547.67 502.74 6.96-18.47 6. rBed2.grd 541.5 507. 6.96-18.47 7. rBed2.grd 609.95 497.87 6.96-18.47 Pipe

8. rBed2.grd 607.48 503.35 6.96-18.47 9. rBed2.grd 603.78 506.39 6.96-18.47

10. rBed6.grd 549.52 500.3 34.51-46.02 Line

11. rBed6.grd 551.37 498.48 34.51-46.02 12. rBed6.grd 557.53 499.09 34.51-46.02 13. rBed6.grd 554.45 504.57 34.51-46.02 14. rBed6.grd 559.38 504.57 34.51-46.02 15. rBed8.grd 645.1 498.48 48.13-59.64 Debri

16. rBed8.grd 650.65 500.3 48.13-59.64 17. rBed8.grd 655.58 500.91 48.13-59.64 18. .grd 642.63 506.39 48.13-59.64

.grd 649.42 507. 48.13-59.64

Table 2. XYZ locations of anomalies marked in Figure 10

Tarea we labeled as a debris field.

Figure 11 and Figure 12 are time slices for Railroad Bed Slices 11-20. Table 3presents theanomalousid

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Figure 11. Railroad Bed, Slices 11-20 unmarked

Figure 12. Railroad Bed, slices 11-20 marked

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# Time Slice X Y Depth-cm Comment _______________________________________________________________ 1. rBed14.grd 621.67 505.17 89.61-101.11 Linear 2. rBed14.grd 624.75 506.39 89.61-101.11 3. rBed14.grd 629.68 506.39 89.61-101.11 4. rBed14.grd 634. 507. 89.61-101.11 5. rBed15.grd 544.58 497.87 96.27-107.77 Debris 6. rBed15.grd 548.28 503.35 96.27-107.77 7. rBed15.grd 553.22 506.39 96.27-107.77 8. rBed15.grd 553.83 500.3 96.27-107.77 9. rBed15.grd 550.75 497.26 96.27-107.77 10. rBed20.grd 738.22 496.04 130.78-137.44 Pipe 11. rBed20.grd 734.52 500.91 130.78-137.44 12. rBed20.grd 729.58 504.57 130.78-137.44

Table 3. XYZ locations of anomalies marked in Figure 11.

3.b.2. Possible Grave Area

In numerous discussions with Poarch Band of Creek Indians THPO Robert Thrower, Gail King, and Hunter Johnson, the possibility of Native American graves on the north side of the Railroad Bed was discussed (Figure 8, Number 2). Some 12,000 Native Americans were brought to the landing during the Removal period by Railroad and by wagon and were shipped out on the Tennessee River. Some undoubtedly were sick, one reportedly died.

The GPR revealed numerous anomalies that could be characterized as possible graves. No test excavations were conducted so the nature of the anomalies is unknown. These unique anomalies appeared as a cluster and were surprisingly quite shallow. Compare Figures 14 (graves not marked) with Figure 13 (marked graves). Anomalies that could be graves are shown in Figure 14. Note the anomalies are numbered and the corresponding XYZ locations are shown in Table 4.

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Figure 13. Possible grave anomalies marked, Slice 1.

# Time Slice X Y Depth-cm Grave _______________________________________________________________ 1. lbbx1.grd 698.27 536.98 0.-112.3 1 2. lbbx1.grd 694.39 539.57 0.-112.3 2 3. lbbx1.grd 696.98 530.95 0.-112.3 3 4. lbbx1.grd 690.5 535.26 0.-112.3 4 5. lbbx1.grd 694.39 518.03 0.-112.3 5 6. lbbx1.grd 690.94 522.77 0.-112.3 6 7. lbbx1.grd 684.89 522.77 0.-112.3 7 8. lbbx1.grd 675.83 526.65 0.-112.3 8 9. lbbx1.grd 678.85 530.95 0.-112.3 9 10. lbbx1.grd 677.55 516.31 0.-112.3 10 11. lbbx1.grd 670.65 523.63 0.-112.3 11 12. lbbx1.grd 667.19 516.74 0.-112.3 12 13. lbbx1.grd 658.13 519.75 0.-112.3 13 14. lbbx1.grd 655.54 525.78 0.-112.3 14 15. lbbx1.grd 658.13 534.83 0.-112.3 15 16. lbbx1.grd 647.34 533.11 0.-112.3 16

Table 4. XYZ points, possible graves

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Figure 14. Grave area, graves not marked (Slice 1)

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3.b.3 Grave Area Extension

This area is an extension of the grave area heading west (Figure 8, Number 3). It may contain 1 or more possible graves. More prominent, however, are linear features that may be pipes extending from

Figure 15. Grave area extension, anomalies not marked

the Nitrate Plant under the Railroad Bed. Compare the marked anomalies in Figure 16 with the XYZ points in Table 5. Then compare with Figure 8, Number 3. The possible pipe extension from the Nitrate Plant is strongly suggested.

# Time Slice X Y Depth-cm Comment _______________________________________________________________ 1. lbbxx1.grd 611.61 535.44 0.-6.96 Possible grave 2. lbbxx1.grd 591.61 515.91 0.-6.96 Probable pipe 3. lbbxx1.grd 586.45 521.77 0.-6.96 4. lbbxx1.grd 581.29 527.63 0.-6.96 5. lbbxx12.grd 596.77 514.6 77.2-84.16 Possible pipe 6. lbbxx12.grd 587.74 518.51 77.2-84.16 7. lbbxx12.grd 583.23 524.37 77.2-84.16 8. lbbxx9.grd 600. 514.6 56.31-63.27 Linear hooklike 9. lbbxx9.grd 604.52 516.56 56.31-63.27 10. lbbxx9.grd 609.03 519.16 56.31-63.27 11. lbbxx9.grd 614.84 522.42 56.31-63.27 12. lbbxx9.grd 617.42 517.86 56.31-63.27 13. lbbxx9.grd 618.71 513.95 56.31-63.27

Table 5. Anomalies and their XYZ locations, Grave Extension Area

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Figure 16. Grave Area extension, anomalies marked

3.b.4 Pavilion The Pavilion sector comprises an area under consideration for interpretive development featuring the construction of a building in which the history of Tuscumbia Landing and its ecosystem will be featured (Figure 8, Number 4). The area was surveyed with GPR in two sections which were appended together. Figure 17 shows all 20 depth slices for the Pavilion. Compare with Figure 18 which shows depth slices marked for slices 5, 11. The 3 linear anomalies in slice 5 suggest 3 sides of a foundation (Table 6). These are also seen in slices 2-6. At slice 11, linear anomalies suggest a possible road bed (Figure 18, Table 6). There are numerous other anomalies in the Pavilion area that are not accounted for in the present report. Investigators can determine these anomalies by examining the animations and test them when the time is appropriate.

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Figure 17. Pavilion, XYZ unmarked. Note foundation, Pav 2-6.

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Figure 18. Pavilion XYZ anomalies marked, note Pav 5, 11.

# Time Slice X Y Depth-cm Comment _______________________________________________________________

1. pav5.grd 648.4 448.38 28.15-39.66 Foundation 2. pav5.grd 651.41 450.62 28.15-39.66 3. pav5.grd 654.42 452.88 28.15-39.66 4. pav5.grd 655.93 455.12 28.15-39.66 5. pav5.grd 658.56 452.5 28.15-39.66 6. pav5.grd 660.44 451. 28.15-39.66 7. pav5.grd 662.32 448.75 28.15-39.66 8. pav5.grd 664.95 446.88 28.15-39.66 9. pav5.grd 664.2 443.5 28.15-39.66 10. pav5.grd 661.94 441.62 28.15-39.66 11. pav5.grd 660.06 439.75 28.15-39.66 12. pav11.grd 642.39 432.62 70.23-81.74 Road Bed 13. pav11.grd 644.64 438.62 70.23-81.74 14. pav11.grd 647.28 443.5 70.23-81.74 15. pav11.grd 649.53 448.38 70.23-81.74 16. pav11.grd 652.54 431.5 70.23-81.74 17. pav11.grd 653.29 435.25 70.23-81.74 18. pav11.grd 654.42 441.25 70.23-81.74 19. pav11.grd 655.17 446.88 70.23-81.74 Table 6. Pavilion XYZ anomaly locations

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3.b.5. Visitor Center

The area designated Visitor Center is the possible site of a center welcoming visitors to Tuscumbia Landing (Figure 8, Number 5). The area was surveyed in 2 sections and contains numerous, non-descript anomalies and other anomalies we tentatively identify as a road bed, unknown linear features, and a debris field (Figures 19, 20). The XYZ locations of these linear anomalies whose function is not known are shown in Table 7. Testing may reveal the nature of these anomalies.

Figure 19. Visitor Center, XYZ anomalies not marked.

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.

Figure 20. Visitor Center XYZ anomalies marked

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# Time Slice X Y Depth-cm Comment _______________________________________________________________

1. vis10.grd 545.25 479.8 0.-11.23 Road Bed 2. vis10.grd 541.69 484.88 0.-11.23 3. vis10.grd 539.15 489.95 0.-11.23 4. vis10.grd 557.46 480.31 0.-11.23 5. vis10.grd 553.39 486.4 0.-11.23 6. vis10.grd 550.34 491.48 0.-11.23 7. vis11.grd 519.83 489.95 69.02-80.53 Linear feature 8. vis11.grd 523.39 489.45 69.02-80.53 9. vis11.grd 527.46 488.94 69.02-80.53 10. vis11.grd 535.08 487.42 69.02-80.53 11. vis11.grd 543.22 486.91 69.02-80.53 12. vis11.grd 549.83 488.94 69.02-80.53 13. vis11.grd 555.93 491.98 69.02-80.53 14. vis14.grd 501.02 488.94 89.61-101.11 Debris field 15. vis14.grd 501.02 484.88 89.61-101.11 16. vis14.grd 503.56 482.85 89.61-101.11 17. vis14.grd 506.61 483.86 89.61-101.11 18. vis14.grd 511.69 483.35 89.61-101.11 19. vis14.grd 515.25 485.38 89.61-101.11 20. vis14.grd 515.25 490.46 89.61-101.11 21. vis14.grd 512.71 491.48 89.61-101.11 22. vis14.grd 507.63 491.48 89.61-101.11

Table 7. XYZ locations for Visitor Center anomalies

3.b.6. Nitrate Plant.

The Nitrate Plant GPR data can be seen in Figure 8, Number 6. A significant portion of the area was mounded and rough terrain for the GPR antenna. It was hoped that the pipes coming out of the nitrate plant, extending under the Railroad Bed, and into the graves extension area would be imaged. Data along both X and Y directions was collected and processed. Unfortunately, the pipes were faint if at all. It is possible that the pipes are clay or terracotta and do not contrast well with the surrounding soil matrix. It is also possible that the 400MHz antenna signal did not reach the depths of the pipes.

# Time Slice X Y Depth-cm Comment _______________________________________________________________

1. allmtx12.grd 586.69 475.03 77.5-89. Pipe 2. allmtx12.grd 590.29 478.13 77.5-89. 3. allmtx12.grd 592.87 479.68 77.5-89. 4. allmtx12.grd 595.44 483.29 77.5-89. 5. allmtx12.grd 624.78 482.77 77.5-89. Pipe 6. allmtx12.grd 618.6 485.35 77.5-89. 7. allmtx12.grd 612.94 490. 77.5-89.

Table 8. XYZ points for possible pipes, Nitrate Plant

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Figure 21. Nitrate plant, 20 slices unmarked

Figure 22. XYZ points for possible pipes, Nitrate Plant

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4. Mapping.

Feature data was collected for Tuscumbia Landing using both a Trimble ProXRT with a Zephyr antenna and a Trimble GeoXH. Data was collected during leaf off conditions during January and March. This allowed the GPS units to collect data with minimal canopy obstructions. Major line features such as the main road (red line), wagon trail (black dashed line) and bluff line (green dashed line) were collected at 1 second interval. Many corners of the local grid system were positioned with wooden stakes and then GPS (red dots). All GPS data was differentially corrected using Trimble’s Pathfinder Office. Data was then exported as shapefiles to ESRI’s ArcMap for mapping and display. Coordinate system used was defined as NAD1983 UTM Zone 16N meters.

Figure 23. Feature data

The main baseline (Figure 23, yellow line) was established on the old Railroad Bed and was defined in a localized coordinate system in meters by starting at 500E, 500N. The end of the main baseline was at 745E, 500N. At both the being and at the end of the main baseline, iron pins were set and these two IPs were tied to three trees that had nails set with a distance to them. From this main base line additional grids were layout for additional geophysical data collection.

All geophysical data was collected and processed in the local coordinate system. The data was then georeferenced using ESRI’s georeferencing tool. With the data now

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reference to UTM 16N coordinates it could be overlaid with all data. This was done with the GPR data, Mag data (Figure 24) and the EM data.

Figure 24. Georeferenced geophysical data

With all data georeferenced both feature data and multiple years of aerial imagery and digital ortho photography can be used and viewed as additional layers. In one instance there was a 1935 black and with photo that was geo referenced and overlaid.

Conclusions. Somehow, Tuscumbia Landing survived the ravages of time. It sits today on a spit of land basically untouched. Geophysical mapping and georeferencing the geophysical data was a strong effort at Tuscumbia Landing, a very special place on the planet. In order to interpret the full meaning of the geophysical data, this report, the companion data CD, and LandAir Survey’s TruView imagery and autocad drawing which provided the base map for the geophysical work, should be read together. The Flythrough provided by LandAir Surveying should be examined. It was made possible by converting the GPR data to a point cloud and merging this data set with the laser

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in e the identity of the

anomalies and institute protection measures where warranted.

scanning data. Much remains to be tested on the ground. We recommend test unitsthe Graves area, the Railroad Bed, and the Pavilion to determin