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Investigating Archaeological Sites, Cemeteries, and Soils with Ground-Penetrating Radar in Florida

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Title: Investigating Archaeological Sites, Cemeteries, and Soils with Ground-Penetrating Radar in Florida
Physical Description: Mixed Material
Copyright Date: 2008

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Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UFE0019201:00001

Permanent Link: http://ufdc.ufl.edu/UFE0019201/00001

Material Information

Title: Investigating Archaeological Sites, Cemeteries, and Soils with Ground-Penetrating Radar in Florida
Physical Description: Mixed Material
Copyright Date: 2008

Record Information

Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UFE0019201:00001


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INVESTIGATING ARCHAEOLOGICAL SITES, CEMETERIES AND SOILS, WITH
GROUND-PENETRATING RADAR INT FLORIDA




















By

CHRISTOPHER CHILTON


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2007
































O 2007 Christopher Chilton


































To my family: Jennifer, Richard, Elizabeth, Cynthia, Richard Jr. and Randall, and all my friends
who have helped through the years.









ACKNOWLEDGMENTS

This research could not have been completed without the advice, guidance and support

from numerous individuals. The integration of multiple disciplines required the assistance of

many friends, colleagues and mentors. Chiefly, I would like to express my gratitude for the vital

support, advice and input from my diverse committee. Dr. Mary Collins was essential to my

understanding and interest in soil science. Her passion for teaching helped create a remarkable

environment for learning and critical thinking. She was an inspiration for all of her students and I

will always appreciate the commitment she had in my education. Dr. James Davidson provided

unique insight and knowledge because of his archaeological expertise. His work on African-

American cemeteries allowed for a critical understanding of much of my research. I was most

fortunate to learn from him not only in the classroom, but in the field as well. Dr. John Schultz

provided valuable counseling and support for my research. His technical and practical

understanding of my work was a tremendous help and allowed me to work through difficult

problems. I was most fortunate to have a committee that provided valuable comments and

patience while writing this thesis.

The Department of Soil and Water Science at the University of Florida has fostered a great

environment for cooperative learning. Never have I seen so many professors and students who

are genuinely interested in each others work and who are willing to assist without reservation.

Dr. Willie Harris has been a wonderful mentor and a remarkable scientist who helped me as well

as many other students throughout his great career. My fellow graduate students who not only

shared an office, but much more, assisted me throughout my research. Dr. Larry 'Rex' Ellis,

Thomas Saunders and Kelly Fischler were instrumental in my graduate school development and

eagerly assisted me whenever needed. I would like to recognize those undergraduate students

who assisted me on many occasions: Victoria Gardner, Aja Stoppe and Leanna Woods. I would









also like to recognize Dr. Rocky Cao, Lisa Stanely and Genero Keehn at the Environmental

Pedology and Land Use Laboratory at the University of Florida for their assistance with my soil

analyses.

I would like to express my gratitude to the archaeological community that guided me

through many years of support and inspiration. Dr. Kathleen Deagan and Al Woods took me

from the basement of the Florida Museum of Natural History to the field. Their support guided

me to the wonderful people of Southeastern Archaeological Research Inc. The confidence and

opportunity afforded me by Dr. Anne Stokes and James Pochurek allowed for my archaeological

development for which I will always be grateful. Dr. Robert Austin, Dr. Elizabeth Carlson and

Dr. Deborah Mullins have not only had a great impact on my archaeological maturation but have

offered assistance and support for my research.












TABLE OF CONTENTS


page


ACKNOWLEDGMENTS .............. ...............4.....


LIST OF TABLES ............ ...... .__ ...............9....


LIST OF FIGURES .............. ...............12....


AB S TRAC T ............._. .......... ..............._ 15...


CHAPTER


1 INTRODUCTION ................. ...............17.......... ......


Tool s and Method ol ogy of GP R. ............_...... .............. 18..
GPR Antennas ............. .. ... ._ .............. 18....

Radar Propagation and Parameters ............. .. ... ...............21......

Properties and Materials Affecting Radar Propagation ......____ ........._ ..............22
History of GPR .............. .... ...._ .... .......__.. ...........2
Archaeological and Cemetery Application of GPR. ........___....... .._ .........___......25
History and Use of GPR Mapping in Archaeology and Cemeteries .............. ....................26
Soils of Florida ............. ...... ...............29...
Soil Taxonomy .............. ...............29....

Diagnostic Surface Horizons ........._..... ...._... ...............30....
Histic Epipedon ........._.._.. ...._... ...............3 1...
M ollic Epipedon ................. ...............32........ ......
Umbric Epipedon............... ...............32
Ochric Epipedon ........._..... ...._... ...............32.....
Diagnostic Subsurface Horizons .............. ...............32....
Albic Horizon .............. ...............33....

Argillic Horizon............... ...............33
Cambic Horizon............... ...............33

Spodic Horizon ........._..... ...._... ...............34.....
Soil Orders in Florida ........._.._.. ...._... ...............34...
A lfisol s .............. ...............34....
Entisols .............. ...............34....
Hi stosol s .............. ...............3 5....

Incepti sol s............._ ........ ...............35.....
M ollis ol s..............__....._.. ...............36..

Spodosol s............... ...............3
Ulti sol s .....__ ................. .........._.........3

Obj ectives of the Study ..............__.......... ...............37...

2 FIELD SITES .............. ...............38....


Study Site Selection .....__ ................. ........._._.........3












Newberry Cemetery ................. ...............38.................
Description .............. ...............38....
S oil s ................. ...............3.. 9..............
Cultural History ................. ...............41.......... .....
Oakland Cemetery Site ................. ...............43........... ....
Description .............. ...............43....
S oil s ................. ...............43.......... .....
Cultural History ................. ...............45.......... .....
Historic Archaeological Site ................. ...............46................
Description .............. ...............46....
S oil s ................. ...............46.......... .....
Cultural History ................. ...............48.......... ......
Prehistoric Archaeological Site .............. ...............49....
Description .............. ...............49....
S oil s ................. ...............50.......... .....
Cultural History ................. ...............51.......... .....


3 MATERIALS AND METHODS .............. ...............53....


Site Criteria............... ...............53

Soil Sampling............... ...............54
Soil Analyses .............. ...............55....

Physical Analysis............... ...............56
Chemical Analysis............... ...............56
Statistical Analysis............... ...............57
GPR Data Collection .............. ...............57....

GPR Analysis................ .... ............5
GPR Post-Processing Analysis............... ...............59

Study Sites .............. ...............60...
Newberry Cemetery............... ...............60
Oakland Cemetery ................. ...............61.......... .....
Historic Archaeological Site............... ...............63..
Prehistoric Archaeological Site .............. ...............64....


4 RE SULT S .............. ...............65....


Newberry Cemetery ................. ...............65.......... ......
S oil Phy si cal Analy si s ................. ...............65................
Soil Chemical Analysis ................ ...............67..
GPR-Soil Results for Newberry Cemetery ................. ...............70...............
The 500-MHz antenna............... ...............70
The 900-MHz antenna............... ...............73

Oakland Cemetery .............. ...............77....
S oil Phy si cal Analy si s ............__..... ___ ...............77...
Soil Chemical Analysis ............... .. ...............78..
GPR-Soil Results for Oakland Cemetery ................. ...............81......__ ...
The 500-MHz antenna............... ...............8 1












The 900-1VHz antenna............... ...............83
Prehistoric Archeological Site .............. ...............84....
S oil Phy si cal Analy si s ............_...... ._ ............... 5....
Chemical Analysis.................... .... ...................8
GPR-Soil Results for the Prehistoric Archaeological Site .............. .....................8
The 500-1VHz antenna............... ...............89
The 900-1VHz antenna............... ...............93
Historic Archeological Site............... ...............95..
Soil Physical Analysis ............_...... ._ ...............95...
Soil Chemical Analysis .............. .............. ................9
GPR-Soil Results for the Historic Archaeological Site ......____ ..... ...__ ..............99
The 500-1VHz antenna............... ...............99
The 900-1VHz antenna............... ...............102
Summary ............ ..... .._ ...............105...


5 DI SCUS SSION ............ ..... ..__ ............... 106..


Newberry Cemetery ................. ...............107......... ......
Oakland Cemetery ................. ...............110......... ......
Historic Archaeological Site ................. ...............113................
Prehistoric Archaeological Site ................. ...............117...............
Ground-Penetrating Radar Comparisons ................. ...............120................
GPR-Cemetery .............. ...............120....
GPR-Archaeological Sites............... ...............121.
Sum mary ................. ...............122......... ......


6 CONCLUSIONS .............. ...............128....


APPENDIX


A SOIL DESCRIPTIONS .............. ...............132....


B PARTICLE-SIZE ANALY SI S ............... ...............14


C SOIL CHEMICAL ANALYSES ................. ...............144...............


D GPR PROFILE S ............ ..... .__ ...............149..


E STATISTICS .............. ...............153....


LIST OF REFERENCES ............ ......__ ...............157...


BIOGRAPHICAL SKETCH ............_...... ...............164...










LIST OF TABLES


Table page

1-1 Typical relative dielectric permittivities (RDPs) of common materials. ...........................24

1-2 Diagnostic summary of the four epipedons used to classify soils in Florida. ................... .3 1

1-3 Cation exchange capacities (CEC) of soil materials (Birkeland 1999). ................... .........31

2-1 Graves at the Newberry Cemetery. Preliminary Report, Southeastern Archaeological
Research, Inc. Gainesville, Florida. .............. ...............42....

3-1 Data points for the four corners of the cemetery boundary. The proj section system
used was UTM, NAD 1983, Zone 17 North. ......___. .... ... ._ ...............61

3-2 Data points for the four corners of the cemetery boundary. The proj section system
used was UTM, NAD 1983, Zone 17 North. ......___. .... ... ._ ...............63

3-3 Data points for the four corners of the historic archaeological survey area. The
proj section system used was UTM, NAD 1983, Zone 17 North. .............. ................64

4-1 Selected soil chemical analysis of the Newberry Cemetery natural and anthropogenic
soils along transects 14 and 17. The EC (EC), extractable (Ext.),............... ................6

4-2 Selected values of chemical properties of the Oakland Cemetery natural and
anthropogenic soils along transect 2. The EC (EC), extractable (Ext.), ................... .........81

4-3 Selected values of chemical properties from natural and anthropogenic soils at
prehistoric archaeological site. The EC (EC), extractable (Ext.),............... .................8

5-1 Coordinate positions of the Newberry cemetery of selected transects and location of
graves. ................ ...............110..._ __.......

A-1 Official description of Jonesville soil series in Alachua County, Florida. ................... ...132

A-2 Soil description of Jonesville series at the Newberry gravesite natural soils (NGNS)....133

A-3 Official description of Candler soil series in Orange County, Florida. ........................... 134

A-4 Soil description of Candler series at the Oakland gravesite natural soils (OGNS),
Orange County, Florida. ............. ...............135....

A-5 Official description of Orlando soil series in Lake County, Florida. .............. ..... ........._.136

A-6 Soil description of Orlando series at the prehistoric archaeological natural soils
(PANS)................. ..............13

A-7 Official description of Immokalee soil series in St. Johns County, Florida. ................... 138










A-8 Soil description of Immokalee series at the historic archaeological natural soils
(H AN S). .............. ...............139....

B-1 Soil data from the Newberry Cemetery Anthropogenic Soils (NCAS) and the
Newberry Cemetery Natural Soils (NCNS) ................. ...............140........... ...

B-2 Soil data from the Oakland Cemetery Anthropogenic Soils (OCAS) and the Oakland
Cemetery Natural Soils (OCNS)............... ...............141

B-3 Soil data from the Prehistoric Archaeological Anthropogenic Soils (PAAS) and the
Prehistoric Archaeological Natural Soils (PANS) ................. ................ ......... .142

B-4 Soil data from the Historic Archaeological Anthropogenic Soils (HAAS) and the
Historic Archaeological Natural Soils (HANS) ................. .............. ......... .....143

C-1 Soil data for the Newberry Cemetery Anthropogenic Soils (NCAS) from selected
transects. Extractable (Ext.). NCAS Transect 22 15N/21E ........._._..... ....._.._. .......144

C-2 Soil data for the Newberry Cemetery Anthropogenic Soils (NCAS) from selected
transects. Extractable (Ext.). NCAS Transect 14 5N/13E ................. ......................144

C-3 Soil data for the Newberry Cemetery Anthropogenic Soils (NCAS) from selected
transects. Extractable (Ext.). NCAS Transect 10 8N/9E ................. ........___..........144

C-4 Soil data for the Newberry Cemetery Anthropogenic Soils (NCAS) from selected
transects. Extractable (Ext.). NCAS Transect 14 9N/13E ................. ......................145

C-5 Soil data for the Oakland Cemetery Anthropogenic Soils (OCAS) from selected
transects. Extractable (Ext.). OCAS Transect 9 40N/10E ................. ............ .........145

C-6 Soil data for the Oakland Cemetery Anthropogenic Soils (OCAS) from selected
transects. Extractable (Ext.). OCAS Transect 22 40N/54W ................. .....................145

C-7 Soil data for the Oakland Cemetery Anthropogenic Soils (OCAS) from selected
transects. Extractable (Ext.). OCAS Transect 22 14N/52W ................. .....................146

C-8 Soil data for the Prehistoric Archaeological Anthropogenic Soils (PAAS) from
selected transects. Extractable (Ext.). PAAS Transect 2 2N/1E............... .................14

C-9 Soil data for the Historic Archaeological Anthropogenic Soils (HAAS) from
selected transects. Extractable (Ext.). HAAS Test Unit 17, Transect 1 52N/44E ...........146

C-10 Soil data for the Historic Archaeological Anthropogenic Soils (HAAS) from selected
transects. Extractable (Ext.). HAAS Test Unit 17, Transect 1 50N/44E ................... ......146

C-11 Soil data for the Historic Archaeological Anthropogenic Soils (HAAS) from selected
transects. Extractable (Ext.). HAAS Test Unit 17, Transect 3 52N/46E ................... ......147










C-12 Soil data for the Historic Archaeological Anthropogenic Soils (HAAS) from selected
transects. Extractable (Ext.). HAAS Test Unit 17, Transect 3 51N/46E ................... ......147

C-13 Soil data for the Historic Archaeological Anthropogenic Soils (HAAS) from selected
transects. Extractable (Ext.). HAAS Test Unit 17, Transect 3 50N/46E ................... ......147

C-14 Soil data for the Historic Archaeological Anthropogenic Soils (HAAS) from selected
transects. Extractable (Ext.). HAAS Test Unit 18, Transect 8 50N/40E ................... ......147

C-15 Soil data for the Historic Archaeological Anthropogenic Soils (HAAS) from selected
transects. Extractable (Ext.). HAAS Test Unit 18, Transect 8 52N/40E ................... ......147

C-16 Soil data for the Historic Archaeological Natural Soils (HANS) from selected
transects. Extractable (Ext.). HANS, Transect 12 48N/30E ................. .....................148

C-17 Soil data for the Historic Archaeological Natural Soils (HANS) from selected
transects. Extractable (Ext.). HANS, Transect 14 40N/20E ........._.._.... ......_.._. ......148

E-1 Results of t-tests for Newberry Cemetery natural soils (NCNS) and Newberry
Cemetery .........._ _.......__ ...............153...

E-2 Results of t-tests for Oakland Cemetery natural soils (OCNS) and Oakland Cemetery .154

E-3 Results of t-tests for Prehistoric archaeological natural soils (PANS) and Prehistoric
archaeological anthropogenic soils (PAAS) samples ................. .......... ...............155

E-4 Results of t-tests for Historic archaeological soils (HANS) and Historic
archaeological anthropogenic soil (HAAS) samples. ............. ...............156....










LIST OF FIGURES


Figure page

1-1 Scale of relative depth of penetration to resolution for ground-penetrating radar
antennas............... ...............20

1-2 A schematic of reflected and scattered electromagnetic waves as they are transmitted
through differing soil properties.. ............ ...............21.....

2-1 Location of research sites in Alachua County, Lake County, St. Johns County, and
Orange County, Florida. ............. ...............39.....

2-2 Soil survey map showing soil series and complex at the Newberry cemetery .. ............... .40

2-3 Soil depth to limerock variability of an Alfisol in Alachua County, Florida. ...................41

2-4 Soil survey map showing the Candler-Apopka soil complex at the Oakland cemetery....44

2-5 Photograph of an Entisol profile in Florida. ............. ...............45.....

2-6 Soil survey map showing soil series and complex at the historic archaeological site.......47

2-7 Photograph of an Immokalee soil series profile. ............. ...............48.....

2-8 Photograph of an excavation at the prehistoric archaeological site along the
southwest shore of Lake Apopka, Montverde, Florida ......... ................. ...............50

2-9 Aerial photograph (1999) of the prehistoric archeological site at Monteverde
showing shovel tests and test unit location (Austin 2006)............... ...............51.

3-1 Aerial photograph of Oakland Cemetery from 1947. Site boundary is highlighted in
red. ............. ...............62.....

4-1 Depth distribution of total clay content of natural transectt 17) and anthropogenic
transectt 14) soils at the Newberry cemetery............... ...............66

4-2 Depth distribution of Transect 14 pH values and Transect 17 pH values at the
Newberry cemetery ................. ...............67.......... ......

4-3 Ground-penetrating radar profiles of the Arenic Hapludalf using a 500-MHz antenna
along transect 17 .............. ...............72....

4-4 Ground-penetrating radar profiles of anthropogenic altered Arenic Hapludalf ................73

4-5 Ground-penetrating radar profile of anthropogenic altered Arenic Hapludalf .................74

4-6 Ground-penetrating radar profile of natural Arenic Hapludalf using the 900-MHz
antenna along transect 17............... ...............75...











4-7 Ground-penetrating radar profile of anthropogenic Arenic Hapludalf using a 900-
MHz antenna along transect 14............... ...............76...

4-8 Depth distribution of pH values for Transect 2 at the Oakland cemetery. ......................79

4-9 Ground-penetrating radar profile using the 500-MHz antenna with two suspect
graves from a Lamellic Quartzipsamment. ................ ....................................83

4-10 Ground-penetrating radar profile using the 900-MHz antenna of two suspect graves
in a Lamellic Quartzipsamment ................. ...............85................

4-11 Depth distribution of pH values for transects at the prehistoric archeological site. ..........87

4-12 Ground-penetrating radar profiles of a natural Psammentic Dsystrudepts using the
500-M Hz antenna. ........... ..... .._ ...............91....

4-13 Ground-penetrating radar profiles of an anthropogenic Psammentic Dsystrudepts
using the 500-MHz antenna. ........... ..... .._ ...............92...

4-15 Ground-penetrating radar profiles of an anthropogenic Psammentic Dsystrudepts
using the 900-MHz antenna. .............. ...............94....

4-16 Depth distribution of selected pH values for transects at historic archaeological site.
Historic site data did not exceed 0.50 m. ............. ...............97.....

4-17 Ground penetrating radar profiles of a natural Arenic Alaquodos using the 500 MHz
antenna.. ............ ...........10

4-18 Ground-penetrating radar profiles of an anthropogenic Arenic Alaquods using the
500-M Hz antenna. ........... ..... .._ ...............102...

4-19 Ground-penetrating radar profiles of a PANS using the 900-MHz antenna. A)
Background filter is applied and antenna noise is removed. ............. .....................0

4-20 Ground-penetrating radar profiles of a historic archaeological anthropogenic soil
using the 900-MHz antenna. ........... ..... .._ ...............104..

5-1 Example of a root ball inversion caused by severe weather in Newberry cemetery
area. ........... ..... ._ ...............109...

5-2 GPR profile at Newberry cemetery of transect 22 using 500-MHz antenna. Grave is
outlined demonstrating how a vertical feature produces scattering. .............. ..............110

5-3 Photograph of excavation unit from the historical archaeological site. Wall footer/
trench is located in southwest corner of unit. ................ .......... ............. .....15

5-4 Ground-penetrating radar profile (GPR) of the prehistoric archaeological natural soil
(PANS) using the 900-MHz antenna. ....__ ......_____ ......___ ............1










5-5 Photograph of soil in abandoned excavation unit from the prehistoric archaeological
site.. ............ ..........11

5-6 Ground-penetrating radar profile using 500-MHz antenna from the Newberry
cemetery anthropogenic soils (NCAS). ............. ...............124....

D-1 Ground-penetrating radar (GPR) transect 22 of the Newberry Cemetery
Anthropogenic Soils (NCAS) using 500-MHz antenna .........__ ...... ...__ ............149

D-2 Ground-penetrating radar (GPR) transect 22 of the Newberry Cemetery
Anthropogenic Soils (NCAS) using 500-MHz antenna .........__ ...... ...__ ............149

D-3 Ground-penetrating radar (GPR) transect 4 of the Oakland Cemetery anthropogenic
Soils (OCAS) using 500-MHz antenna. ....__ ......_____ .......__ ...........15

D-4 Ground-penetrating radar (GPR) transect 4 of the Oakland Cemetery Anthropogenic
Soils (OCAS) using 500-MHz antenna. ....__ ......_____ .......__ ...........15

D-5 Ground-penetrating radar (GPR) transect 4 of the Oakland Cemetery Anthropogenic
Soils (OCAS) using 500-MHz antenna. ....__ ......_____ .......__ ...........15

D-6 Ground-penetrating radar (GPR) transect 2 of the Prehistoric Archaeological
Anthropogenic Soils (PAAS) using 500-MHz antenna...................... ...............15

D-7 Ground-penetrating radar (GPR) transect 2 of the Prehistoric Archaeological
Anthropogenic Soils (PAAS) using 500-MHz antenna .....................151

D-8 Ground-penetrating radar (GPR) transect 2 of the Prehistoric
ArchaeologicalAnthropogenic Soils (PAAS). ............. ...............15 1....

D-9 Ground-penetrating radar (GPR) transect 3 of the Historic
ArchaeologicalAnthropogenic Soils (HAAS) using 500-MHz antenna. .......................152

D-10 Ground-penetrating radar (GPR) transect 3 of the Historic Archaeological
Anthropogenic Soils (HAAS) using 500-MHz antenna. ......._____ .... ..__ ............152

D-11 Ground-penetrating radar (GPR) transect 3 of the Historic Archaeological
Anthropogenic Soils (HAAS) using 500-MHz antenna. ............. ....................15









Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science

INVESTIGATING ARCHAEOLOGICAL SITES, CEMETERIES AND SOILS WITH
GROUND-PENETRATING RADAR INT FLORIDA

By

Christopher Chilton

May 2007

Chair: Mary E. Collins
Major: Soil and Water Science


Ground-penetrating radar (GPR) is an efficient and nondestructive instrument for

collecting information below the ground surface relating to potential archaeological sites and

cemeteries. This research assessed the application of GPR technologies for archaeological

investigations with multiple soil orders of Florida. By differentiating the archaeological anomaly

from natural pedogenic properties, a qualitative interpretation of a site can determined. Four sites

were selected based upon archaeological context and soil properties in Florida. The

anthropogenic sites included two cemeteries; the Newberry cemetery located in Alachua County

and the Old African American Cemetery in Orange County. The one historic archaeological site

is located in St. Johns County and a prehistoric archaeological site is in Lake County. Each site

had a different soil order commonly encountered in Florida (Alfisols, Entisols, Inceptisols and

Spodosols). Natural and anthropogenic soils were surveyed using 900-and 500-MHz antennae.

Soil samples were collected along GPR surveyed transects and analyzed for physical and

chemical properties including texture, pH, and electrical conductivity. Post-processing of the

GPR data was conducted to augment profile interpretation and assess the differences in imagery

of the 900- and 500-MHz antennae.









Results of the GPR and soil analyses revealed that each was dependent upon the

anthropogenic context. Diagnostic horizons had a greater influence than soil order classification

on the successful application of GPR on archaeological sites and cemeteries. Soil physical

properties, specifically texture, had a greater overall impact than soil chemical properties on the

radar propagation in every site. The 500-MHz antenna was preferred over the 900-MHz antenna

for general performance in all four research sites, regardless of soil order. 500-MHz antenna

preference for the GPR was based on depth of radar wave penetration and the general

background noise associated with the higher frequency antenna. Though diagnostic surface

horizons and soil texture influenced GPR interpretation, this study showed that GPR is

applicable in a wide variety of soil and archaeological contexts in Florida.









CHAPTER 1
INTTRODUCTION

Ground-penetrating radar (GPR) has become a comprehensive and reliable remote sensing

tool for gathering and processing geophysical information. GPR is a method that provides rapid

and non-invasive identification of subsurface features and materials. Recent technological

innovations, such as real time video display with post processing software on the control unit,

have improved the effectiveness of data acquisition and processing along with increasing the use

and application of this tool. The technological advances in GPR in the past decades have allowed

its use today to become common and accepted procedures in many disciplines.

Many land-use activities have the potential for the application of GPR. Numerous

scientific and commercial fields such as: geology, mining, engineering, construction, agriculture,

environmental science and archaeology are turning to real-time and nondestructive data

acquisition tool. Also, because of the easy and rapid use of this instrument, there has been an

increase in the utilization for surveying, mapping, mitigating and delineating subsurface features.

Soil scientists and geologists have used GPR to map subsurface horizons, delineate karst

features, detect sinkhole formation, and differentiate bedrock units for industrial minerals

(Doolittle and Collins 1998, Collins 1990, Puckett 1990, and Dekeyser 2005). The military is

able to save lives by detecting buried land mines and unexploded ordinance (Hyde 1997).

Engineers have applied this efficient technology to high-speed rail trackbed investigations

associated with high-speed trains (Doshi and Al-Nuaimy 2006). GPR was used in May 2005 for

a search mission after a mountain accident in the Chilean Andes involving the death of 45

military troops (Casassa 2006). The success of GPR in the past has created strategies for the

future; scientists are planning to conduct geophysical surveys on Mars (Olhoeft 1998).









Tools and Methodology of GPR

GPR is a method that is able to produce large amounts of high resolution, multi-

dimensional information through the transmission of electromagnetic waves. This tool actively

produces multiple pulses of energy derived from a control unit. Fiber-optic cables transmit a

digital signal to and from the antennas; the raw data derived from the generated electrical pulses

are received and displayed in a video or printed format (Conyers and Goodman 1997, Davis and

Annan 1989, and Schultz 2003). The transmission of electromagnetic radar pulses travel through

the earth's surface and any of these pulses which are reflected will be received and recorded.

Energy is transmitted and energy is received through antennas; the frequencies of these antennas

range from a bandwidth of about 10 megahertz (1VHz) to 1500 1VHz.

GPR Antennas

Transmitting and receiving antennas used for GPR are configured in either a monostatic or

bistatic mode. The monostatic mode is where the transmitting and receiving antennas is at a zero-

offset, there is no separation from the point of transmission to the point of reception. This allows

for a self-contained unit with less variability. On the contrary, the bistatic mode has two separate

points for transmission and reception of radar energy. Separation of these independent points can

be manipulated in the field to determine radar wave velocity. The recorded time of transmission

from one antenna to another through a known distance of material can be measured and thereby

calculate the radar wave velocity (Conyers and Goodman 1997). Configuration choices for GPR

antennas may be based on the type of field questions asked.

Different GPR applications demand different antennas. The choice for standard

transmitting antennas is generally straightforward, the dipole or bowtie traveling-wave antenna

have been primarily used for the impulse-based radar system (Daniels 1996). The transmitting

antenna emits an elliptical cone of radar energy with the apex of the cone located in the center of









the antenna (Davis and Annan 1989, Schultz 2003). The elongated shape of the elliptical is

usually parallel to the direction of the antenna movement along the ground (Conyers 2004,

Conyers and Goodman 1997). This shape of transmitted radar energy plays a role in survey

parameters. The size and shape of the transmission cone is primarily dependent upon the

physical properties of the soil, thereby dictating the spatial parameters of collecting data in the

field.

Some antennas have an added feature that allow for a reference mark to be employed

during a survey. This mark is activated when a trigger switch is pushed on the antenna handle by

the operator, allowing for a spatially referenced point along a GPR transect. Marked points on

the radar transect are coordinated with field grid markers that can be located using a global

positioning system (GPS) to create a three-dimensional reference points (Conyers 2004, Conyers

and Goodman 1997, Tischler 2003).

Techniques for GPR vary widely, each according to their application. There are restrictions

to the range of the operating system. Selections of antennas are based on the depth and resolution

for area of study (Davis and Annan 1989). Figure 1-1 illustrates the commercial range of antenna

frequencies and properties. Higher frequency antennas (e.g. 900 MHz) offer a greater ability to

differentiate features of varying size from a surrounding matrix, but are limited in depth of

penetration. Conversely, the lower frequency antennas (e.g. 120 MHz) allow for greater depth at

which a GPR signal will be reflected back to the surface, but provide a lower range of resolution.

Any radar frequency used will be determined upon not only by the depth of study and the

subsurface features of that study, but upon the inherent properties of site area.











Antenna Frequency Properties Blu' = Pcso~lullan
Red = Depin







700 mHz

600 mHz















Figure 1-1. Scale of relative depth of penetration to resolution for ground-penetrating radar
antennas. Resolution capability is inversely proportional to depth of penetration.
(From Tischler, 2003. Integrating Ground-Penetrating Radar, Geographic Information
Systems and Global Positioning Systems for Three- Dimensional Soil Modeling).

The type of antenna frequency used is limited by the properties of the material that is

surveyed. A receiver bandwidth in excess of 500 MHz, and typically 1 GHz, is required to

provide a typical resolution of between 5 and 20 cm, depending on the relative properties of the

soil (Daniels 1996). Antennas used in most archaeological contexts are the 500-MHz and 900-

MHz antennas; while lower frequency antennas are often used to interpret the geomorphology of

many prehistoric sites. Equipment choice can be a compromise between resolution, scope of

signal processing, and the ability to effectively offset the negligible properties of subsurface

material. Frequency selection is dependent upon site parameters and survey obj ectives. Annan

and Cosway (1994) listed a number of factors controlling frequency selection: (i) electrical









properties of the host environment, (ii) depth resolution, (iii) clutter dimension, (iv) depth of

exploration and target size, (v) site access and (vi) any external interference.

Radar Propagation and Parameters

The effectiveness of the radar is dependent upon the ground in which it penetrates;

specifically the properties beneath the surface. GPR has been used to investigate ice, water, rock,

pavement, soil and many other natural and human environments (Olhoeft 1996). The success of

these numerous applications has all been based on the ability of the transmission of

electromagnetic waves.

ORGANIC
MATTER ANTENNA
GROUND SURFACE


!! SAND




:i CLAY




BE DROC K

Figure 1-2. A schematic of reflected and scattered electromagnetic waves as they are transmitted
through differing soil properties. Antenna displayed is a monostatic system with both
a transmitter (Tx) and receiver (Rx). (From Schultz, 2003. Detecting Buried Remains
in Florida Using Ground-Penetrating Radar. Doctoral Thesis in Forensic
Anthropology, University of Florida, p.28, Figure 4).

The physical properties that affect the radar waves as they pass through a medium are electrical

conductivity and magnetic permeability (Annan et al. 1975). Radar pulses generate a wavefront

which propagates downward and is partially reflected by any change in the electrical bulk

properties of the soil (Figure 1-2) (Vaughan 1986), GPR measures the changes in these










properties. Any of the electromagnetic energy that is reflected because of changes in these

properties is amplified and recorded through the receiving antenna.

Use of GPR requires the system operator to accurately understand the constraints of the

study area. Two factors must be determined prior to the operation of the equipment: the dielectric

constant and the range. Accurate configuration of the system will determine the proper depth of

signal penetration and resolution of that signal. Both range and dielectric constant are system

parameters that are set individually, but are dependent upon one another. An accurate range

cannot be set without a general knowledge of the subsurface dielectric constant.

The range is a parameter that has a time value measured in nanoseconds (ns.) A range

value is entered into the GPR control unit in order to determine how long to record received

signals after a radar pulse has been transmitted (Geophysical Survey Systems Inc. 1994). Any

portion of the radar pulse which can penetrate into the subsurface material, reflect from a

boundary or obj ect and return to the antenna is recorded and displayed in real-time. As time is

increased for the range setting, radar waves will penetrate the subsurface further in depth, yet

resolution and reflected data decrease with depth. There are finite restrictions to range settings

and the distance for which radar waves will travel. The time (ns) for a pulse to reach an obj ect or

boundary is dependent upon the material through which it passes. Restrictions to the range are

reliant upon frequency of the antenna and the dielectric constant.

Properties and Materials Affecting Radar Propagation

Electromagnetic pulses that are transmitted from the GPR antenna pass through space. If

this space is in a vacuum, then an electromagnetic pulse will travel at 0.2999 meters per

nanosecond. However, GPR is used over the ground and the materials located beneath the

surface range from soil, rock, ice, water and air to anthropogenic remains. Materials in the earth

have a range of dielectric properties which allow the passage of electromagnetic energy. The









more electrical conductivity a given material has the less dielectric it is; therefore for maximum

radar-energy penetration, a highly dielectric medium with a low electrical conductivity is

required (Conyers and Goodman 1997).

The dielectric constant is a parameter required in the calibration for the maximum effective

depth of the GPR energy waves. This constant, also known as the relative dielectric permittivity

(RDP), is measured against the heterogeneity of an obj ect or earth' s natural subsurface system.

The RDP is the capacity of a material to store, and then allow the passage of electromagnetic

energy (von Hippel 1954). Dielectric characteristics of materials vary greatly. Calculation and

measurement of RDP is based on of the velocity of an electromagnetic pulse in a vacuum. When

a pulse travels in a vacuum at 0.2998 meters per nanosecond then the RDP is 1 (Conyers and

Goodman 1997). Materials with a low dielectric constant, allow the passage of electromagnetic

waves with little or no dissipation, while higher conductivity will create greater dissipation of

radar waves or attenuation.

Soil and consolidated earthen material are both filters and boundaries to radar waves,

depending upon the dielectric properties of the medium. Dielectric constant values range from air

(low), to sea water (high) and vary according to the properties associated with subsurface

materials (Table 1-1), (Davis and Annan 1989, Geophysical Survey Systems Inc. 1994).

Materials composed primarily of air are less electrically conductive and are termed to be less

dielectric. Conversely, the RDP of water is of the order of 80, therefore even small amounts of

moisture will cause a significant increase of the relative permittivity of material (Daniels 1996).











Table 1-1. Typical relative dielectric permittivities (RDPs) of common materials.
Material RDP
Air 1
Dysand 3-5
Limestone 4-8
Clay 5-40
Concrete 6
Dysandy coastal land 10
Average organic-rich surface soil 12
Marsh or forested land 12
Organic-rich agricultural land 15
Saturated sand 20-30
Fresh water 80
Sea water 81-88
Modified from Davis and Annan (1989) and Geophysical Survey Systems, Inc. (1987).

History of GPR

GPR has a history that was a precursor to its own rediscovery. The first practical

application of GPR was in 1929 by W. Stern for determining the depth of an Austrian glacier

(Olhoeft 1996). The United States Air Force developed better radar systems in the late 1950's

when several pilots crashed on icy runways because conventional radar was transmitting through

the ice and reading inaccurate altitudes. In 1960, John Cook made the first proposal for the

detection of subsurface reflections using radar in his article "Proposed monocycle-pulse, VHF

radar for airborne ice and snow measurements." From this work, the development of radar

systems to detect subsurface reflections continued. The subsurface radar system from the late

1920's had not changed all that much when used for the Apollo 17 lunar mission in 1972. The

need for alternative applications by the U.S. military during the Vietnam War created an increase

in GPR development and advancement, hence the redundant use of acronyms. Radar is an

acronym for Radio Detection and Ranging.

Commercial availability for GPR technology was introduced in 1972 by Geophysical

Survey Systems Inc. (GSSI), ushering in a myriad of applications and extensive research to









universities and private companies alike. GPR development increased during the 1970's; Moffatt

and Puskar (1976) improved the target-to-clutter ratio of antennas and thereby increased

subsurface reflection accuracy. With increased antenna capability, new methods were able to

estimate the location of mines, faults and underground tunnels (Cook 1975, Moffatt and Puskar

1976). GPR technology in the early 1980's was used as a pedologic tool (Collins 1992, Doolittle

1982) and to investigate the depth of groundwater (van Overmeeren 1994). GPR has been used

to map bedrock surfaces, detect sinkholes and delineate karst features (Collins et al., 1990,

Doolittle and Collins 1998, Puckett 1990). As advancements in technologies emerged during the

1980's, methods of processing and analyzing GPR data became more widespread and available

to a variety of scientific Helds. This increase in available GPR technology created many diverse

applications.

Archaeological and Cemetery Application of GPR

The Hield of archaeology has long relied upon the use of multiple scientific disciplines,

ranging from geology to zoology. Techniques and tools from these other areas of studies have

worked well in shaping the way archaeologists conduct their research. In the past three decades,

the use of GPR has provided a means for analyzing an archaeological site in a nondestructive

way. GPR is a tool that increases the spatial extent of a study area, while reducing the amount of

time to conduct a preliminary survey. Data is collected in real-time and conveyed to the operator

allowing for rapid reconnaissance.

Archaeologists often destroy the area they study through excavation. GPR nondestructively

records and saves all data that are collected, thereby allowing decisions to be made prior to

disturbing a site. The capability of GPR to estimate depth and shape of buried obj ects make its

use suitable to grave detection (Bevan 1991). Varying site characteristics and context are also

amenable to the use of radar. To determine whether artifacts were present in a site often required










a great deal of exploratory digging, thereby greatly increasing time and expense (Vaughan

1986). Field season at an archaeological site is usually short and successes are often dependent

upon many variables including equipment, personnel and weather. Surveys conducted with GPR

may narrow the scope of interest and reduce the labor-intensive process associated with

excavation.

History and Use of GPR Mapping in Archaeology and Cemeteries

The increased success of GPR in archaeology has been related to the various circumstances

in which the technology is used. Advances in techniques have created greater interpretation of

data. Until recently, GPR was simply used to identify subsurface "anomalies" that may not have

represented archaeological features (Conyers and Cameron 1998). Fast and accurate

archaeological surveying of large areas using GPR has even created new word usage.

Geophysical 'prospection' is now considered a standard method for detecting buried

archaeological features and structures (Leckebusch 2003). No matter the terminology, GPR has

become recognized as an important tool for numerous archaeological applications.

The archaeological applications of GPR range from spatial parameters to temporal context.

Spatially, surveys are able to locate sites and delineate anthropogenic boundaries, while

superposition can be conveyed through stratigraphic sequencing and the mapping of features

(Dalan and Bevan 2002, Conyers 1995, Conyers and Goodman 1997, Sassaman et al. 2003,

Schultz 2003). The absence or presence of soil heterogeneity may also indicate an anthropogenic

site. This is contextual and site specific. A GPR survey of a possible prehistoric mound from the

Effigy Mounds National Monument in Iowa revealed symmetrical curving strata more consistent

with a prehistoric cultural mound than caused by natural phenomena (Whittaker and Storey,

2005). Reinterpretation and nondestructive analyses of the mounds has continued for the past 40










years. Whittaker and Storey (2005) affirm the potential of GPR for archaeological preservation

with ongoing research at Effigy Mounds National Monument. Sufficient knowledge of local

landforms and processes may allow a determination of earthen features (Dalan and Bevan,

2002). When taken in context to surrounding geomorphology, sequencing and uniformity in

radar profiles may suggest possible human augmentation.

GPR use can incorporate surface anomalies with subsurface uniformity. Discontinuities

between cultural features with the natural soil matrix extend spatial parameters for delineating

the lateral extent and thickness of shell middens (Chadwick and Madsen 2000). Near surface

lithological features create discrete anomalous characteristics. Such highlighted features may

expose potential voids beneath such as gravestone chambers (Lorenzo and Arias 2005). GPR in

archaeology not only highlights discontinuities within the soil, but reveals materials and obj ects

anomalous to a known area.

The successful use of GPR for locating historic graves has ranged widely, often with

varying results in the same site area. Intrasite soil conditions and burial practices may vary,

enabling clear and distinct reflections or attenuation. Even with mixed success, GPR is

considered the most reliable geophysical tool for locating graves. A model study by Bevan

(1991) was conducted at nine different sites in the United States that used both GPR. One study

site, the Poor Farm Cemetery in Rockville, Maryland, had no marked graves. Radar reflections at

this site exhibited grave features; however, excavation showed the reflection to be a natural

change in the soil. The study Bevan (1991) conducted at the different sites illustrated the varying

degree of success with GPR on cemetery graves.

Controlled archaeological and forensic tests have been conducted to establish the efficacy

of GPR. Schultz (2003) tested the applicability of GPR to detect buried bodies in two different









Florida soils. Pig cadavers, with varying weights and sizes, were selected as surrogates for

human bodies and buried at two depths. Factors that controlled decomposition were monitored

and assessed with the GPR. Schultz (2003) concluded that depth and time were the most

significant factors in the decomposition of the cadavers.

Another controlled test conducted with GPR was a simulated archaeological site in Illinois.

This study replicated features present in some North American archaeological sites under a

controlled environment (Hildebrand et al. 2002). Features included pig and dog burials in

mounds, isolated pits, hearths, artifact clusters and structures. In addition to the GPR, seismic

reflection imaging (SRI) was used. This allowed the authors to compare geophysical methods

based on reflection imaging in anthropogenic soil conditions. Both methods worked well in the

study with the GPR providing a more accurate depth range to target (Hildebrand et al. 2002).

A combination of pedological insight with the use of GPR allows for comprehensive site

analysis. Distinct change in soil structure or bulk density may enable a GPR operator to

distinguish cultural augmentation from natural occurrences. Surficial features, such as circular

trample zones associated with animal feeding areas, were identified with time-slice depth maps

created by processed radar data (Nishimura and Goodman 2000). A 300-MHz antenna was

chosen for a Roman period site in Wroxeter, England as a consequence of anticipated depth of

stratigraphy. This approach in data acquisition increases opportunity in locating site specific

feature characteristics. Prior knowledge of a site's archaeological component, along with

physical soil properties, such as soil texture, can dictate proper antenna use. Another Roman

period building in the United Kingdom was surveyed using GPR; a 450-1VHz antenna was

chosen over a lower frequency due to the potential signal attenuation in clay-rich soils at great









depths (Linford and Linford 2004). These are two examples of balancing depth of penetration

with the potential of known feature resolution in similar archaeological site parameters.

Soils of Florida

To understand the limitations and efficacy of GPR in Florida, characteristics and properties

of the soil will be discussed. Soil "is a collection of natural bodies on the earth' s surface, which

may be modified or created by human activity, containing living matter and capable of

supporting plants" (Collins 1992). All soils are the product of the environment factors in which

they are associated. The Hyve soil forming factors (time, parent material, topography, climate and

biota) were described first by Dokuchaev (1883) and later by Jenny (1941). Distinct soil forming

factors associated with Florida are reflected in the dynamic and varied soil properties. Resulting

pedogenic processes are the basis for describing and classifying soils.

Soil Taxonomy

Soils in the United States are classified according to Soil Taxonomy (Soil Survey Staff,

1999). Specific information is based on this system of soil classification will be from the Soil

Survey Staff (1999), unless cited otherwise. Soil Taxonomy is based on measurable or

observable properties of soils as described in the field and laboratory. Classification indicators

include diagnostic subsurface and surface (epipedon) horizons based on physical, mineralogical,

morphological, and chemical properties. Soil indicators are referenced and classified to a

maximum depth of two meters, while diagnostic features may be restricted to or exceed this

depth.

Soil Taxonomy is hierarchical with the following categories from the highest to lowest: (i)

Order, (ii) Suborder, (iii) Great Group, (iv) Group, (v) Family and (vi) Series. Soil Orders are the

highest and most inclusive category, while the soil Series is the most comprehensive category.

The state of Florida has seven of the twelve soil Orders: Alfisols, Entisols, Histosols, Inceptisols,









Mollisols, Spodosols and Ultisols (Collins 1997). Soil Order classification is based on the

presence or absence of maj or diagnostic surface or subsurface horizons.

Diagnostic Surface Horizons

All diagnostic surface horizons are termed epipedons, based on the Greek words epi,

meaning over or upon, and pedon, soil. Epipedons that exist in Florida are either organic (histic,

folistic) or mineral (mollic, ochric, and umbric). A summary table of the Hyve epipedons in

Florida is listed in Table 1-2, with the folistic epipedon not included due to the very specific

nature of its classification and limited coverage. Diagnostic surface horizons that have been

altered through anthropogenic influences could be considered anthropic epipedons.

Understanding diagnostic surface horizons is vital in determining successful GPR application.

Epipedon determination may also establish soil Order classification.

Epipedons range in physical, chemical and morphological characteristics. Physical

parameters include mineral and organic soils, while morphological include soil thickness,

structure, and color. Chemical diagnostic properties associated with epipedons include base

saturation (B S) percentage including cation exchange capacity (CEC), listed in Table 1-3.

Particles <0.002 mm in size in Florida have a net negative charge. Positively charged cations are

attracted to these negatively charged surfaces. Most of the cations attracted to the sites are

exchangeable. These soil chemical properties have a tremendous impact on the performance of

the GPR. According to Daniels (2004) soils with a high CEC are more attenuating to GPR than

soils with an equivalent percentage of low CEC. This is similar for soils with elevated levels of

BS, more cation activity in the soil will increase attenuation in the GPR.










Table 1-2. Diagnostic summer of the four eidons used to classic soils in Florida.
Epipedon Base Typical Thickness Organic Horizon General
Saturation Color Content Description
(B.S.) (moist)
Hi stic Low to 10YR 2/1, > 20 cm > 12% Organic Saturated >
high. 0- 2/2 30 days a
100% year
Mollic > 50% 10YR 3/3 > 25 cm > 0.6 to Mineral > 50% B.S.
or less 12%
Ochric 0-100% 10YR 4/4 < 25 cm < 0.6% Mineral Fails to
or more meet
definition of
all other
epipedns
Umbric < 50% 10YR 3/3 > 25 cm > 0.6 to Mineral Similar to
or less 12% Mollic but
less than
50% B.S.

Table 1-3. Cation exchange caacities (CEC) of soil materials (Birkeland 1999).
Soil Material Net Negative Charge (cmol c/k)
Humus (Organic) 100-550
Vermiculite 100-180
Smeetite 80-120
Chlorite 15-40
Gibbsite 4-14
Goethite 4-12
Kaolinite 2-5

Histic Epipedon

The histic epipedon (from Greek histos, meaning tissue) is a horizon 20 cm or more thick

of organic soil material consisting of either muck, peat, hemic or a combination. This organic

soil horizon overlies a mineral subsurface horizon and has a very low bulk density. This

epipedon is saturated with water at some period (30 days or more) of the year and are common in

very poorly drained areas in Florida. Histic epipedons have high electric conductivity, high BS

and very high CEC, (Table 1-2).









Mollic Epipedon

A mollic epipedon is a mineral surface horizon with high accumulated organic matter

content (from .6 to 12 % organic carbon throughout), allowing for a dark brown (10 YR 3/2) to

black moist color (10 YR 2/1). Other diagnostic properties associated with a mollic epipedon are

it must exceed 25 cm in thickness and have a B.S. greater than 50%. Mollic epipedons have a

high electric conductivity and a high CEC.

Umbric Epipedon

Morphologically, the umbric epipedon appears to have the same general characteristics as

a mollic epipedon; the only difference is the B.S. is lower than 50%. Electric conductivity and

CEC are lower than the mollic epipedon.

Ochric Epipedon

The most common mineral epipedon in soils is the ochric (Collins 1992). The

morphological description of an ochric epipedon is a default category by not meeting the

classification of any other epipedons. This surface horizon does not have the diagnostic

properties associated with other epipedons; it is low in organic matter and not dark or thick

enough to be a mollic or umbric epipedon. Electric conductivity and CEC have a wide range of

values in an ochric epipedon and often tend to be lower than most epipedons.

Diagnostic Subsurface Horizons

Diagnostic subsurface horizons provide morphological, mineralogical and chemical

characteristics that enable the soil to be classified. Many of the diagnostic subsurface horizons

are defined by clay mineralogy and chemical components. Only 5 of the more than 18 subsurface

horizons (Soil Survey Staff, 1999) used to classify soils apply to this research and will be

considered. All 5 are located in Florida and pertinent to this study: albic, argillic, cambic, kandic,

and spodic.









Albic Horizon

An albic horizon is defined by a light-colored horizon of eluviation that is low in, organic

matter, clay minerals and iron and aluminum oxides. This horizon is generally associated above

subsurface illuviated horizons in Florida: spodic, argillic, or kandic (Collins 1997). Albic

horizons are predominately made up of white to light gray sand (ex: 10YR 7/1-8/1) particles in

Florida with low electrical conductivity and low CEC.

Argillic Horizon

An argillic horizon is a subsurface illuviation of high-activity silicate clays. The

accumulation of layer-lattice silicate clays in the argillic horizon is due to physical translocation

and chemical transformation soil processes. Concentrations of clay translocated from upper

horizons are called argillans. These interstitial clay skins often coat and form on the surface of

peds and within soil pores between sand and silt particles; it is often the amount of clay that

determines an argillic horizon. An argillic horizon is an illuvial horizon > 15 cm thick in a soil

with 15 to 40% clay. Argillic horizons have medium values of electrical conductivity and a wide

range of CEC.

Cambic Horizon

A subsurface soil horizon that is weakly developed with some color, texture and structure

change is classified as a cambic horizon. The cambic horizon has very little or no significant

accumulation and is characterized by the alteration or minor accumulation of mineral material.

This diagnostic subsurface horizon is weakly to moderately weathered and relates a recent soil

genesis. Cambic horizons have moderate to high electrical conductivities and low to moderate

range of CEC.










Spodic Horizon

An illuvial horizon having an accumulation of colloidal organic matter, Al, and/or Fe

oxides is classified as a spodic horizon. Spodic horizons are highly illuviated subsurface soil

horizons commonly located in Florida' s pine flatwood forests. The black or reddish organic

illuvial horizon is very acidic. Often spodic horizons in Florida underlay highly eluviated

subsurface horizons or mineral and organic epipedons. The amorphous accumulation of organic

matter and oxides in a spodic horizon will increase the bulk density and lower the pH in relation

to surrounding horizons.

Soil Orders in Florida

According to soil taxonomy there are currently 12 soil orders assigned to soils throughout

the world. Soil taxonomy is the classification scheme in use in the United States, and is based

mainly on observable properties (Birkeland 1999). A wide range of soil orders (7) are present

throughout Florida: (i) Alfisols, (ii) Entisols, (iii) Histosols, (iv) Inceptisols, (v) Mollisols, (vi)

Spodosols, (vii) and Ultisols.

Alfisols

Alfisols are classified by the subsurface diagnostic argillic horizon. An argillic horizon

and also a thin gray to brown ochric epipedon are commonly associated with this soil Order.

Alfisols in Florida are characterized by a subsurface accumulation of silicate clays (argillic

horizon) and have a moderate to high level of bases (> 35%). Alfisols are moderately leached

soils that are commonly associated with mixed hardwood forests in well drained to poorly

drained soils.

Entisols

This Order is a very common and morphologically diverse group of soils in Florida.

Entisols are recently developed or show little if any pedogenic development. Parent materials of










this soil Order range from to a marine, aeolian, or alluvium deposition in Florida. Diagnostic

horizons are limited and may include ochric epipedons and albic horizons, yet argillic or spodic

horizons may be present below a depth of 2 m (Collins, 1997, W.G. Harris, personal

communication, 2006, Schultz, 2003). Entisols are primarily quartz sand and may range from

well to poorly drained soils; the CEC and electric conductivity range of these soils are widely

varied as well.

Histosols

Histosols are comprised of organic soil material. Histosols have soil organic material in

half or more of the upper 80 cm, or in two-thirds of a soil overlying shallow rock. Due to the

high organic content, these soils are generally black to dark brown in color and have high water-

holding capacities on a mass basis. Not all wetlands in Florida contain Histosols, however all

Histosols (except Folists) occur in wetland environments. Common names for Histosols are peat

(slightly to moderately decomposed) or muck (highly decomposed). Generally, Histosols have

very high amounts of CEC.

Inceptisols

Inceptisols are the 'inception' of soil development with few diagnostic features. Unlike

Entisols, Inceptisols show more significant soil development in both surface and subsurface

horizons. Umbric and ochric epipedons are very common in this soil Order, yet may have a

mollic or histic surface as well. Subsurface horizons, such as albic or cambic horizons are

represented with the establishment of a structural, textural or color change. Soil properties

associated with Inceptisols range from textures of a sandy loam to fine sand, and moderate to

high CEC in the clay fraction of recently developed illuvial horizons (Collins 1997).









Mollisols

Mollisols are mineral soils which have an accumulation of high organic matter, with a

B.S. greater than 50%. All Mollisols have a dark, humus-rich mollic epipedon 18-25 cm in

thickness (10 cm over bedrock); however a histic epipedon may overlay a mollic. In Florida,

Mollisols have argillic, albic or cambic diagnostic subsurface horizons. A maj ority of Mollisols

are associated with grassland or prairie environments; however, in Florida this soil Order is

primarily poorly to very poorly drained conditions (Collins 1997). High ranges of CEC and low

ranges of electric conductivity occur due to the high organic matter and B.S. inherent to

Mollisols.

Spodosols

Spodosols are mineral soils with a spodic horizon within 2 m of soil surface. Spodic

horizons often underlay very leached eluvial albic horizons, but may have argillic or kandic

horizons as well. Epipedons associated with Spodosols range from ochric to a thin histic. These

soils are often sandy, acidic forest soils with low bases and high amounts of Al. Most Spodosols

occur in poorly drained pine flatwood regions throughout Florida (Collins 1997). Spodosols have

low CEC ranges, while electric conductivity may be quite high down to the spodic horizon.

Ultisols

Ultisols are highly weathered soils with silicate clays and low bases. Intense leaching

from upper horizons allow for the translocation of clay minerals into argillic or kandic

subsurface horizons. Prolonged leaching of Ultisols is characterized by a low amount of bases

(<3 5%), relatively acidic silicate clays, and Fe and Al oxides. Ultisols may have either an ochric

or umbric epipedon. This soil is commonly associated with stable landscapes with mature forest

vegetation. Ultisols are morphologically similar to Alfisols, but are more highly weathered and









acidic. In Florida, Ultisols range from well-drained to poorly drained soils (Collins 1997).

Ultisols have low CEC ranges, with moderate electric conductivity.

Objectives of the Study

The general obj ective of this research was to demonstrate the efficacy of GPR on

anthropogenic sites with selected Florida soils Orders. The suitability of GPR for archaeological

and gravesite detection is not always applicable to pedogenic models. The purpose of this

research is to assist archaeologists and GPR operators to better understand the context of

anthropogenic influences on natural soils.

* Conduct GPR surveys to obtain information about the selected archaeological sites and
cemeteries in Florida

* Establish the extent of archaeological and cemetery soil properties in producing distinctive
anomalous responses.

* Document resolution differences between 900-MHz and 500-MHz GPR antenna usage for
obtaining anthropogenic targets in study areas.

* Determine the suitability of GPR on various Florida soil Orders in an archaeological and
gravesite context by demonstrating the influences of soil physical and chemical properties.









CHAPTER 2
FIELD SITES

Study Site Selection

Four sites were studied to evaluate the application and feasibility for the use of GPR in an

archaeological and cemetery context in the North-Central and Central Florida (Figure 2-1). Field

sites were based on archaeological context and soil variability. Archaeological sites included a

prehistoric habitation site in Lake County on the shore of Lake Apopka and a historic structure

site in St. Johns County, north of St. Augustine. The two historic cemeteries date from the late-

nineteenth century in Orange County to the early and mid twentieth century in Alachua County.

Both the Orange and Alachua County sites are associated with African-American cemeteries.

These study areas were based on four different soil Orders. In Florida soils there are

contrasting subsurface features, i.e. argillic horizons, spodic horizons, layers (organic); lithic

(bedrock) contacts; wetting fronts; and lamellae that are easily exhibited by GPR (Collins 1992).

The properties from a maj ority of Florida soils are conducive to the use of GPR (Collins et al.

1996, Doolittle et al. 2002). The four field study sites selected will elucidate potential concerns

for the use of GPR when applied with soil properties in an anthropogenic context.

Newberry Cemetery

Description

The Newberry cemetery (Davis Cemetery 8AL4992) is located in Section 34 of Township

9, Range 17 East in western Alachua County, Florida. This site lies east of the Brooksville range

on the Wicomico terrace; underlain by alternately thick layers of Plio-Pleistocene material

overlying loamy marine sediments and limestone bedrock (Thomas et al. 1985). Part of the

Alachua Formation, the Newberry Cemetery site area is in the southwestern part of Alachua

County, where it forms low and rolling hills (Thomas et al. 1985). The substrate materials















































FI 16~01 12 1240Kilorreten1


represent the residuum of post-Eocene formations (Schmidt 1997). This area has been

extensively mined for rock. This formation varies in depth from 8-12 meters (Thomas et al.

1985). Naturally occurring vegetation in this area includes: live oak (Quercus virginiana), laurel

oaks (Quercus laurifolia) and water oaks (Quercus nigra); longleaf pine (Pinus palustris) and saw

palmetto (Serenoa repens).


Figure 2-1. Location of research sites in Alachua County, Lake County, St. Johns County, and
Orange County, Florida.

Soils

The soils at the Davis cemetery are well-developed Alfisols (Thomas et al. 1985). They

are mapped as Pedro- Jonesville complex, with varying depths of argillic horizon; which are so










intermixed, that they cannot be separated at the scale of mapping (Figure 2-2). Mapped areas of

the complex range from 10 to 50 hectares. Pedro soils are fine-loamy, siliceous,


















Trannse:.t 17











Figure 2-2. Soil survey map showing soil series and complex at the Newberry cemetery. The
map was created in ArcGIS 9.1 using data derived from the Alachua County Soil
Survey (Thomas BP, et al. 1985).

hyperthermic, shallow Typic Hapludalfs. The thickness of the solum and the depth to limestone

range from 15-45 cm. The other soil in this complex is the Jonesville series; loamy, siliceous,

hyperthermic Arenic Hapludalfs. Mapped as a complex, the maj or difference between the

Jonesville soil as compared to the Pedro soil is the depth to limestone. Both soils have an argillic

horizon which is from 32-72 cm in depth. Depths to limestone and the argillic horizon greatly

vary within the site. An example of depth to lime rock variability for Alachua County soils is in

Figure 2-3. Overall, this complex has severe limitations for cemetery use.






























Figure 2-3. Soil depth to limerock variability of an Alfisol in Alachua County, Florida.

Cultural history

Three headstones were identified in a heavily wooded area north of Newberry, Florida

along transects 14, 17 and 21 in Figure 2-2. In addition to the marked graves, four suspect graves

were located in immediate vicinity; two linear depression and two uninscribed marble footstones.

All three marked graves were inscribed with name, date of birth and date of death. The graves

were identified bearing the names Catherine Alridge, Willies Davis, and W.J. Long. The earliest

recorded date of death was Willie Davis on February 14, 1892. Catherine Alridge was the most

recent grave, dated to June 4, 1918. All marked graves and linear depressions were in an east to

west alignment, denoting a Western Christian burial pattern. Gravestone type and dates of the

four marked graves are in Table 2-1.









Table 2-1. Graves at the Newberry Cemetery. Preliminary Report, Southeastern Archaeological
Research, Inc. Gainesville, Florida.
Name Date of Birth Date of Death Gravestone Material
Type
Catherine 1832 June 4, 1918 Rounded Marble
Alridge Marker
Willie Davis May 14, 1818 February 14, Shouldered Marble
1892 Marker
W.J. Long May 1867 August 14, Rounded Marble
1916 Marker

Historic research conducted by Southeastern Archaeological Research, Inc. (SEARCH) in

the area was inconclusive as to the original name of the cemetery. No known churches or

homesteads with common last names were connected with the Davis Cemetery. No information

could be found on Catherine Alridge or Willie Davis, while only one report of W.J. Long (black

male) places him in the Newberry area during the year of 1916 (SEARCH 2005). Historic deed

research of the Davis Cemetery area indicated that in the first decade of the 20th century the

property was owned, but not developed, by the Florida Land Development Company and was

sold on July 14th 1910 to the Mutual Mining Company of Marion County (SEARCH 2005).

Located in a mixed hardwood hammock, this site area has a high canopy with little under

story growth. North of the graves are three small cedar trees. Cedar trees were typically planted

near the periphery of cemetery boundaries during the late 19th and 20th century in Florida. The

cemetery boundary is identified to be no larger than 32 m east to west and 25 m north to south.

During the time of the research at this site area a 27 m preservation buffer zone was put in place.

No protective fences or markers are located around the heavily wooded area. A town facility is

adj acent to the Davis Cemetery. As of the fall of 2006, this cemetery does not meet the criteria

for eligible inclusion in the National Register of Historic Places (NRHP).









Oakland Cemetery Site


Description

Located in Orange County, Oakland Cemetery (OR9576), also known as the Old African

American Cemetery, is situated in Section 20 of Township 22, Range 27 East. This site lies south

of Lake Apopka in the southern end of the Central Valley. The Lake Apopka area is underlain by

undifferentiated Plio-Pleistocene sediments and sedimentary deposits of the Hawthorn Group

overly the upper Eocene limestone (Doolittle and Schellentrager 1989, Schmidt 1997, White

1970). The geomorphology of the site area is at the interface of the Central Valley and Lake

Wales ridges, part of the Wicomico Terrace (Doolittle and Schellentrager 1989, White 1970).

Topographic variability, associated with the Central Valley and Lake Wales ridge, range from a

5-12 % slope in the site area (Figure 2-3). Natural vegetation is predominately live oak (Quercus

virginiana), bluej ack oak (Quercus incana), turkey oak (Quercus laevis), and sand pine (Pinus

clausa). Surrounding site area has been used for citrus crops during the past century.

Soils

Oakland Cemetery is predominately comprised of Entisols and Ultisols, and is mapped as

Candler-Apopka fine sands with 5-12% slopes and adj acent, depressional Basinger fine sands

(Doolittle and Schellentrager 1989). The Candler-Apopka complex is an excessively drained

soil. This soil complex is associated with uplands and low ridges (Figure 2-4). Candler soils are

classified as hyperthermic, uncoated Lamellic Quartzipsamments; they form in thick deposits of

aeolian or marine sand. Similar in pattern and proportion to the Candler, the Apopka soil series is

a loamy, siliceous, hyperthermic Grossarenic Paleudult. This soil complex is widespread

throughout the site area. The individual soil series cannot be differentiated on a small scale and

are therefore mapped together as a complex.










































Figure 2-4. Soil survey map showing the Candler-Apopka soil complex at the Oakland
cemetery. The map was created with ArcGIS 9.1 using data derived from the Orange
County Soil Survey (Doolittle and Schellentrager 1989).

Apopka consists of well drained soils that formed in sandy and loamy marine sediment.

Both the Apopka and Candler soil series are morphologically very similar in the upper meter of

each horizon (see Discussion). The Basinger series is classified as a siliceous, hyperthermic

Spodic Psammaquents; which form in sandy marine sediment. These poorly drained soils are in

shallow depressions and along the rim of larger depressions. An example of a Florida Entisol soil

is in Figure 2-5. The homogenous matrix of the C horizon is evident in the uniform subsurface

radar profiles.











Entisol


~w9r r- r~Yc-f
LYIT-
i.
.~ .. ~ =IFi'
:it


Figure 2-5. Photograph of an Entisol profile in Florida.


Cultural History

The Old African American Cemetery is located north of the State Road 50 and Florida

Turnpike intersection. Along the south border of the cemetery is the remnant of the Tavares and

Gulf Railroad (1891-1971) roadbed. No longer an active cemetery, approximate dates of early

graves are from the early 1890's. The last known graves are from as late as 1952. The cemetery

was not affiliated with any religious organizations and African Americans from the surrounding

communities were also buried in the cemetery (SEARCH 2005). Both the citrus crops and the

railroad line facilitated an influx of migrant workers in the area. Many of the people buried in the

cemetery were citrus farmers and service workers. Also, if any of the migrant workers or

possible transients died while in the area, they were buried in the cemetery as well (Deacon









Moore 2006: personal communication). Census searches revealed most of those buried in the

cemetery are originally from North or South Carolina and Georgia (SEARCH 2005, Florida

Census 1920). African American burial practices associated with this site had a significant

relationship with results of the GPR survey and will be discussed in Chapter 5.

Historic Archaeological Site

Description

This British Period occupation site area is located west of the Tolomato River and north

of Marshall Creek in St. Johns County, Florida. The site (8SJ3 149) lies within the Atlantic

Coastal Lowlands and is less than one-half mile west of the Atlantic Ocean on the Pamlico

terrace. This area was formed as barrier islands and lagoons from the Plio-Pleistocene to recent

times (Davis 1997). Silver Bluffs and Pamlico terraces occur in this intercoastal area. Physical

environment is dominated by pine flatwoods, hardwood hammocks and salt marshes. Hammocks

within the Marshall Creek property are associated with the bottomland hardwood wetlands that

border the coastal salt marshes.

Soils

The soils mapped in the site area are weakly to moderately developed Spodosols with

associated Entisols; and are classified as either Myakka or Immokalee (Spodosols) soils (Readle

1983). The Myakka-Immokalee complex is a nearly level, poorly drained sandy soils located on

flat marine terraces in broad flatwood areas (Figure 2-6). Most of the soils in this complex have

loamy to sandy subsoils that are stained with dark organic accumulations. The Myakka series is

Florida' s state soil and is classified as a sandy, siliceous, hyperthermic Aeric Alaquod.

Immokalee soils are classified as sandy, siliceous, hyperthermic Arenic Alaquods (Figure 2-7).

















































Figure 2-6. Soil survey map showing soil series and complex at the historic archaeological site.
The map was created with ArcGIS 9.1 using data derived from the St. Johns County
Soil Survey (Readle 1983).











47












































Figure 2-7. Photograph of an Immokalee soil series profile.

Cultural History

The Tolomato River and Marshall Creek areas have varied historic and prehistoric

archaeological components. Multiple phases of the St. Johns culture occupied northeast Florida

from around 500 B.C. and lasted until shortly after permanent historical settlements occurred in

1565 A.D. (Milanich 1994). A European power struggle of French and Spanish interests

occurred in the St. Johns River area during the mid-16th century (Contact Period: from 1565

A.D.). In 1565 the Spanish, led by Pedro Menendez de Aviles dispatched the French and









established St. Augustine. Chosen for its strategic location, St. Augustine existed as a military

outpost and a base for missionaries for the area (Deagan 1983). The First Spanish Period (1565-

1763 A.D.) in northeast Florida was a rural mix of Franciscan missions, Indian villages, Spanish

cattle ranches and military fortifications (Bond et al. 1990, SEARCH, 2005). During the British

Period (1763-1784 A.D.), rural construction in northeast Florida increased; plantations, industrial

construction, trading posts, slave cabins and plantation houses developed throughout the region

(Bond et al. 1990, SEARCH, 2005).

Numerous excavations were conducted in the Marshall Creek (8SJ3149) area over the last

decade. Extensive amounts of information have been collected on both prehistoric and historic

archaeological components from the site area. Archaeology on 8SJ3149 was conducted in order

to mitigate development in the vicinity. Multiple scientific disciplines were employed to

facilitate the survey and excavation of this site.

Prehistoric Archaeological Site

Description

This prehistoric archaeological site is known as the Montverde site (8LA243), located in the

town of Montverde in Lake County, Florida. The site is situated in an agricultural area on the

west side of Lake Apopka (Figure 2-8). The site 8LA243 is bordered to the east and north by the

lake, and to the northwest by a freshwater marsh. The geomorphology of the area includes Plio-

Pleistocene sediments overlying Hawthorn deposits and upper Eocene limestone (Doolittle and

Schellentrager 1989, Schmidt 1997, White 1970). Lake Apopka lies in the Central Valley,

associated with the Lake Wales and Winter Haven Ridge along the Wicomico terrace (White

1970). The well-drained soils and proximity to Lake Apopka (Figure 2-9) was conducive to long

term citrus cultivation at the site area. Natural vegetation includes live oak (Quercus virginiana),









turkey oak (Quercus laevis), longleaf pine (Pinus palustris), slash pine (Pinus elliottii), and saw

palmetto (Serenoa repens).


























Figure 2-8. Photograph of an excavation at the prehistoric archaeological site along the
southwest shore of Lake Apopka, Montverde, Florida.

Soils

Two soils are mapped with the site area; a well-drained Orlando series and a very well-

drained Entisols classified as the Lake soil series (Furman et al. 1975). Predominately, the site

associated with the Orlando series (Figure 2-6). This series is classified as a sandy siliceous,

hyperthermic Humic Psammentic Dystrudepts. The Orlando series is a nearly level to gently

sloping (0-5%), well-drained sandy soils in association with upland ridges. This Inceptisol

formed in sandy marine sediments and has a thick umbric epipedon. The other soil in the

research site is the Lake series; classified as a hyperthermic, coated Typic Quartzipsamment.














































Figure 2-9. Aerial photograph (1999) of the prehistoric archeological site at Monteverde
showing shovel tests and test unit location (Austin 2006). Shovel tests and excavation
units were conducted prior to survey by Southeastern Archaeological Research Inc.
Soil series information derived from Lake County Soil Survey (Furman et al. 1975).
The Orlando and Lake soil soils make up 93 to 99 percent of mapped areas with
marine sediment on upland slopes of 0-5% (Furman et al. 1975).

Cultural History

Previous excavations in the Montverde site area have indicated the presence of two

archaeological components. Upper levels of the excavation units contained St. Johns Check

Stamp pottery, indicating a St. Johns II occupation site; while the lower levels appear to be a St.









Johns I period, dominated by St. Johns Plain ceramics (Austin 2006). The organic midden base is

an early St. Johns I period with related features dating from as early as 1600 B.C.; while dates

within the midden go up to 400 B.C.(R. Austin, personal communication, 2006). Two cultural

features were identified in an excavation unit as circular, basin-shaped pits with fragments of

burned wood in the sandy fill (Austin 2006). The burned wood associated with pit features

allowed for accurate 14 C dating.









CHAPTER 3
MATERIALS AND METHODS

Site Criteria

Each field site area was selected on the key variables of temporal component, spatial

extent, pedological criteria and availability for research. Every site was to be represented by a

soil Order in Central Florida and not to exceed a survey size of 2 hectares. Selected sites were to

reflect field conditions encountered during standard operating archaeological surveys and

excavations. Every field site contained an element of bioturbation and anthropogenic influence

of varying degrees. A common element in all four research areas were the materials used and the

methods employed. Each individual site will include: archaeological field work, GPR survey,

soil sampling and description. Equipment and software used and soil analyses conducted were

identical for all four sites.

Equipment and Software: All four field sites were surveyed with the same GPR system:

SIR-2000 control unit with 500 MHz and 900 MHz ground-coupled monostatic, dipole antennas

with control unit (Geographical Survey Systems, Incorporated, North Salem, New Hampshire).

Both antennas have marker switches located on the handle and manually controlled by the

antenna operator. The control unit is a digital pulse system, with internal hard drive, keypad and

color screen. GPR files may be viewed real-time in the field or data may be downloaded to an

external computer. Each antenna is connected to the control unit by a 60-meter cable. A twelve-

volt battery powers the GPR unit.

Multiple software packages were used in the field and laboratory for GPR, Global

Positioning System (GPS) and Geographic Information System (GIS) data calculation. For all

four sites, GPR files were downloaded from the field to the computer for post-processing

analyses with Data Transfer Utility for Windows 95 and Windows NT, proprietary software of









GSSI (Geophysical Survey Systems Inc.). Post-processing analyses for the manipulation of GPR

data of all sites were conducted using the same computer software package (ReflexW 2.5X,

Sandmeier Scientifie Software, Karlsruhe, Germany). The primary GIS software package used

was ArcGIS 9.1 (Environmental Research Institute, Redlands, CA.). Two different GPS devices

were used in the acquisition of spatially referenced data, TOPCOM 3C total station with

TOPCOM SC data collector. The Garmin etrex VistaThl handheld GPS receiver was also used.

Soil Sampling

Soil samples were collected on site specific criteria. Collection of anthropogenic soils

samples was uniform in depth and quantity within each site area. Physical data acquisition and

soil sampling was done with a bucket auger (8 cm diameter and 17 cm in length). Archaeological

Hield sites incorporated both bucket auger and hand trowel during excavation. Auger samples

were taken with a bucket auger, which was found to pack and hold a greater range of soil

textures encountered from all four site areas. Soils were described and sampled up to a depth of 2

meters for every site. Anthropogenic soils were described on a site specific basis, with no

maximum depth requirement.

Soil samples of approximately 400-500 g each were collected in the Hield and placed in

labeled plastic bags. Soil descriptions were recorded and sample bags were returned to the

University of Florida Environmental Pedology and Land Use Laboratory. In the pedology

laboratory, soil color was determined by visual comparison on moist samples to a Munsell@ Soil

Color Book (GretagMacbeth, 2000). Morphological descriptions from the field and from NRCS

soil survey data were augmented with laboratory data and are listed in Appendix A. Appendices

B and C list the physical and chemical data from each site.









Two types of sampling increments were used for anthropogenic and pedogenic soils:

1. Natural soil samples were taken from each designated genetic horizon revealed in auger
samples for morphological descriptions and lab analyzed in the laboratory.

2. Anthropogenic soils sampled were taken from 20-30 cm interval (depth) samples for
physical and chemical analysis from surface to appropriate depth.

Soil Analyses

Procedural analyses for all soil samples of the four site areas were identical. Processing of

soil samples was done at the same time, using the same equipment and environmental conditions.

Samples were air-dried, screened through a 2-mm sieve, and stored in Analytical Research

Laboratory (ARL) approved soil sample bags. Each of the 232 collected soil samples was

assigned an individual catalogue number for use in laboratory testing and curation. Site specific

identification numbers (e.g., 8LA243: 8 = state of FL, LA = Lake County, 243 = site #), included

the provenience descriptions.

Soil samples were subj ect to physical and chemical analyses. Specific analyses included:

particle size, pH, organic carbon (OC) content, electrical conductivity (EC), extractable

aluminum (Al), extractable iron (Fe), extractable phosphorus (P), extractable magnesium (Mg),

extractable sodium (Na), extractable calcium (Ca) and extractable potassium (K) contents.

Particle-size analysis was used to determine the percentage of sand, silt and clay for textural

classification and subsequent sand fractionation. Soil pH is known as the "master variable"; this

test is done in order to understand the chemical range and parameters within the soil. The amount

of OC was determined to differentiate between a mineral soil (<12%) and an organic soil. The

percentage of O C may also greatly influence the taxonomic classification of a soil, chemical

properties and indicate the presence archaeological middens.

Amounts of extractables P, Ca, Na, Mg, K, Fe, and Al were analyzed to determine the

extent of anthropogenic influences on a pedologic landscape using the GPR Archaeologists have









used soil chemical analyses as both a temporal and spatial indicator of site habitation. Soil

chemical testing of the four bases (Na, Ca, K, and Mg) along with the two acid cations (Al, Fe)

will allow for an increased understanding of natural and anthropogenic site context. Extractables

P and Ca were analyzed to determine if bone diagenesis occurred in the site areas; both P and Ca

are the two most common minerals in bone (Schultz 2003). Distribution of extractable P is a

good indicator of anthropogenic activity, because mean extractable P is notably lower in

naturally occurring soils.

Physical Analysis

All particle-size analysis was conducted at the Environmental Pedology and Land Use

Laboratory, Soil and Water Science Department, at the University of Florida. Particle-size

distribution analysis was conducted using the pipette method (Gee and Bauder, 1986). Soil

samples of 50 g were treated with hydrogen peroxide and heated on hot plates to oxidize organic

material. The samples were then dispersed with sodium hexametaphosphate in de-ionized water.

Dispersed samples were immersed in a 200 C water bath and pipetted to retrieve the clay

fraction. The clay fractions retrieved were dried and weighed. Sand fractions were obtained

from the original sample and removed of remaining silt and clay, then oven-dried and shaken

through nested sieves. Silt content was derived by the subtraction of sand and clay weight from

the total sample weight.

Chemical Analysis

Organic carbon content, pH, EC, extractables P, Fe, and Al were all analyzed at the

Analytical Research Laboratory, Institute of Food and Agricultural Sciences, Soil and Water

Science Department, at the University of Florida. OC content was determined by a modified

Walkley- Black method of dichromate sulfuric acid (Soil Survey Staff, 1996). The calculation of

pH was done by 1:2 water to soil solution by glass electrode of pH meter and deionized water.









EC was determined by 2:1 deionized water to soil solution using a glass electrode. This

procedure was done because EC is directly related to the amount and distribution of ionic

charges in the soil (McNeill, 1980).

The procedure to determine extractables P, Al, and Fe was using a Mehlich 1 extraction

(Mehlich, 1953). This procedure entails 5 grams of soil sample to be added to 20 ml Mehlich 1

solution (0.05 M HCL and 0.0125 M H2SO4). The solution and sample are shaken for 5 minutes

and filtered through Whatman # 42 paper. The extract is then analyzed by an inductively coupled

plasma-atomic emission spectroscopy (ICP-AES) (EPA Method 200.7, Analytical Research

Laboratory 2006). Mehlich 1 was also used for the analyses of extractables Ca, K, Mg, and Na;

the extract is analyzed by atomic adsorption spectroscopy (AAS).

Statistical Analysis

Statistical analyses of the data was based on a standard two-tailed, paired t-Test. Analyses

of the soil data with a t-Test was used to determine whether two soil samples were likely to have

come from the same two populations that have the same mean. The dependent variables are

based on the pedogenic soils from the site. Anthropogenic soil samples are the independent

variable, measured with the dependent pedogenic soil samples. Data from physical and chemical

soil properties sampled from the site associated with GPR transects. The two-tailed t-Test was

performed to determine if soils from a potential anthropogenic site corresponds to the probability

of the known values of the pedogenic site. The statistical program used to perform the standard

two-tailed, paired t-Test was the Microsoft Office Excel 2003, statistical functions.

GPR Data Collection

Each research site was cleared of underbrush prior to GPR survey. Cleared transect paths

allow for an uninterrupted flow of data collection; thereby minimizing post-processing

corrections. Datum points were acquired for every site by a TOPCOM 3C total station and









TOPCOM SC data collector. Reference points were recorded from the datum points located in

the southwest corner of each site. A hand held GPS receiver was used to correlate spatial

coordinates of transects emanating away from the datum points. The GPS handheld receiver was

used along transects in all four field sites. Signal error due to tree canopy obstruction was

minimized by the GPS receiver being placed over known coordinates and physically rectified by

pull tape.

GPR transects for each site were collected in single line grid formation emanating from

datum point coordinates. A 100-meter pull tape laid out each transect in a north-south direction.

Direction and distance were corrected with the use of GPS and hand held SU7UNTOTM Sighted

compass. Pin flags were placed every one to two meters along each transect. Transects were

spaced in one-meter interval grid patterns. A one meter distance between transects was necessary

for complete site coverage with GPR. An antenna was walked along each transect and referenced

with corresponding intermediary trigger-switch marks associated with measured pin flag points.

The antenna was pulled along the same side of the line for consistency. All sites received the

same spatial reference methodology.

Each site contained different and varying soil properties, and thereby required different

range settings and RDP calibrations to determine time-depth conversions. An accurate

conversion of two-way travel time to depth is necessary before the interpretation of data can

commence. Time-depth calculation was determined by auguring to a known depth just off-site.

At one and two meter depths, water was added to the base of the auger hole and immediately

geo-referenced with the GPR with both 900-MHz and 500-MHz antennas. Ranges and dielectric

constants were established and set on each individual site location and date from this information

and referenced with known RDP ranges.









GPR Analysis

Analysis of GPR data often is conducted in a two-step process. The GPR technology used

in this research allowed for real-time data viewing in the field. This enabled the operator to take

corrective measures in equipment calibration and survey technique. In the field, GPR data files

were viewed using a Color Table of 2 and Color Xform of 2. These visual screen settings are

qualitative and subj ect to viewer preference for optimum data interpretation. Field interpretation

of visual GPR data was considered the preliminary step for overall data acquisition. Often times

transects were discounted and field data were reacquired based upon preliminary field

observations. Raw field data contain extraneous background noise or reflections that make

definitive interpretations difficult. Horizontal scale and vertical scales are often not coordinated

effectively in non-processed data.

GPR Post-Processing Analysis

Post-processing is an important step in GPR analysis and interpretation. Qualitative

assessments are greatly enhanced with the manipulation of GPR data; often images and

anomalies are not clear to the operator until the data has been processed. Interpretive strategies

and procedures for the processing of GPR data are numerous. There are fundamental procedures

in the rectification and manipulation of data sets. Spatial adjustment, both vertically and

horizontally, along with background filtering are primary procedures often employed by the

operator. Processing of GPR profiles required a minimum 4 different procedures in order to

interpret the raw data.

Horizontal adjustment was the first procedure for every GPR file. Linear correction is

necessary because the GPR antenna is not pulled across a transect at a constant speed.

Intermediary marks were created at prescribed intervals along each transect during the collection

of data. The known distances between each interval allows the software to the correct distances










between each mark. This step was a trace interpolation/resorting procedure. Vertical correction

was the next step taken for proper depth. GPR antennas are housed in a fiberglass box and

suspended above the ground surface. The actual distance between the antenna and the ground is

seen as an 'antenna ringing' noise that can be corrected. This 'ringing' is seen as a uniform

reflection image and is included in the original data as part of the profile depth. Elimination of

this noise will set the time transmission depth at 0 ns, as 0 meters; this is done through gain

compensation.

After vertical and horizontal adjustments are made, filtering the files of horizontal banding

is done. This process allows for enhanced viewing of anomalies and the removal of unwanted

clutter. Radar attenuation is filtered out, leaving continuous pedogenic horizons, planar and

point-source anomalies. This procedure is a combination of a running and background removal

process.

Study Sites

Newberry Cemetery

The Alfisols at the Newberry Cemetery are not considered highly suitable soil orders in

Florida for GPR application (Collins et al. 1996). Thus, GPR use for this site is not ideal from a

pedogenic context. However, this site was selected for availability, pedogenic diversity from

other selected soil orders and for the community need. The area is heavily wooded and

surrounded by planted pine. Cemeteries are confined to area no greater than 500 sq m; coupled

with a strict temporal range of less than 30 years. There are numerous occurrences of

bioturbation throughout the site that include animal burrows (krotovinas), tree stumps, root ball

inversion and roots. These subsurface anomalies are detected by the GPR and have varying

influences on both the 900-MHz and 500-MHz antennas.









A total of 24 transects were conducted in the cemetery every meter. Each transect was 20

m in length with marker flags placed every two meters for reference points. The general

cemetery area surveyed and staked at 27 m east to west and 21 m north to south by a previously

contracted survey team (Table 3-1). GPR surveys and soil sample collections were conducted

several times over a five-month period (October of 2005 to February of 2006).

Table 3-1. Data points for the four corners of the cemetery boundary. The proj section system used
was UTM, NAD 1983, Zone 17 North.
Northwest Comer: 17R 0344765 W Northeast Corner: 17R 0344786 W
3283016 N 3283015 N

Southwest Comer: 17R 034464 W Southeast Comer: 17R 0344886 W
3282990 N 3282989 N


Oakland Cemetery

The selection of Oakland Cemetery as a research site was a combination of soil

suitability, anthropogenic criteria and the need for mitigation before future development in the

area. The presence of unmarked graves outside the cemetery boundaries was not known by the

town residents or the local, affiliated church. A survey was conducted in order to determine if

any unmarked graves existed outside the historic boundaries of the Oakland Cemetery. This was

achieved through a combination of archived aerial photographs (Figure 3-3), ethnographic

accounts and a GPR survey.

On the eastern shoulder of the site area is a transition from the Lamellic Quartzipsamment

(Candler) down slope to the Grossarenic Paleudult (Apopka). Both of these series are ideal soils

orders in Florida for GPR applications in a pedogenic context (Collins et al. 1996). Typical

vegetation of these soils is sand pine (Pinus clausa), slash pine (Pinus elliottii), chapman oak

(Quercus chapmanii), live oak (Quercus virginiana, and saw palmetto (Serenoa repens). The area

is subj ect to krotovinas. At the base of the slope is a Spodic Psammaquent (Basinger), which is











seasonally flooded for extended periods of time. Naturally occurring vegetation includes


pondcypress (Taxodium ascendens), sweetgum (Liquidambar styraciflua) and scattered pond


pine (Pinus serotina).





















red.
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course of three days of surveying. The site was staked with survey markers (Table 3-2) in all four

corners prior to the GPR survey.

Table 3-2. Data points for the four corners of the cemetery boundary. The proj section system used
was UTM, NAD 1983, Zone 17 North.
Northwest Corner: 17R 0437596 W Northeast Corner: 17R 0437696 W
3158418 N 3158417 N
Southwest Corner: 17R 0437596 W Southeast Corner: 17R 0437696 W
3158285 N 3158347 N

Historic Archaeological Site

Research interest in the Marshall Creek site (8SJ3149) was based primarily on the historic

occupation component. The field site in St. Johns County contained Spodosols and peripheral

Entisols, which are two of the best soils orders in Florida for GPR applications in a pedogenic

context (Collins et al. 1996). The area is heavily wooded with numerous occurrences of

bioturbation that throughout the site that include; animal burrows (krotovinas), tree stumps and

roots. Large areas of underbrush were cleared to prepare the site and restrict the unwanted

influences of the GPR survey. Both the 900- MHz and 500-MHz antennas were used and had

varying influences on subsurface detection.

The research site at Marshall Creek was a collaborative effort with SEARCH.

Archaeological excavations were conducted in the area over a six-year period. A small scale

GPR survey was conducted in the August 2005 in a known multi-component site area. GPR data

collection was confined to 100 m2 area adj acent to a block excavation. The excavation units were

placed near previously tested units which contained abundant British period materials (Carlson

2005). The coordinates of site area is shown Table 3-3.

A total of 16 transects were placed in a grid pattern and ran in both north-south and east-

west directions. This was conducted to achieve a greater spatial context of any possible historic

features. Transects were 3 to 5 meters in length with half-meter intervals. Interval distance was










reduced due to the depth of potential targets and smaller elliptical radiation footprint. GPR

surveys and soil sample collections were conducted two times over a period of one month.

Table 3-3. Data points for the four corners of the historic archaeological survey area. The
proj section system used was UTM, NAD 1983, Zone 17 North.
Northwest Corner: 17R 0463935 Northeast Corner: 17R 0463926 W
3322503 3322502 N

Southwest Corner: 17R 0463933 Southeast Corner: 17R 0463925
3322494 3322493


Prehistoric Archaeological Site

Preliminary archaeological work at the Montverde site (8LA243) was conducted in 2004

due to possible future development. Independent to the research work, a contract archaeological

firm (SEARCH) began testing with a subsurface survey of 87 shovel tests throughout the proj ect

area. Prehistoric artifacts were recovered from 50 shovel tests; the center and the southwest

corner of the grove were the only areas void of cultural material (Austin 2005). Excavations units

were then placed in areas of high artifact concentration, along the eastern proj ect area. The units

were situated between the citrus grove edges and the lake shore. The site area extends about 25

hectares across an active orange grove. The site area has a marked slope (>5%) from west at 36

m to the lake shore at 21 m above mean sea level.

The scope of the GPR research site area was confined to potential archaeological

concentrations. A GPR survey was conducted from the block excavation areas between previous

T.U. 1 and T.U. 2. The survey began from an Orlando series (Inceptisol) and continued upslope

in to the Lake series (Entisols). A total of 24 transects were conducted in an east to west

direction in order to determine the transition of the umbric epipedon to an ochric epipedon.

Transects were one meter apart and restricted in grid size due to presence of orange trees, and

were referenced off existing excavation unit datum points and handheld GPS receivers.









CHAPTER 4
RESULTS

Results of interpreting GPR profiles and soil analyses are separated into sections covering

the four research sites. Each section will include: (i) physical and (ii) chemical analyses of

anthropogenic and natural soils, (iii) GPR profiles with the 500-MHz antenna and (iv) 900-MHz

antenna of anthropogenic and natural soils. Comparison of all four sites will be covered in the

discussion chapter. A summary of morphological pedon descriptions and selected physical and

chemical properties are given in Appendices A and C. Additional GPR profiles suing the 500-

MHz and 900-MHz antennas are given in Appendix D.

Newberry Cemetery

Located in western Alachua County, Florida, the Newberry cemetery was selected for this

study based on soil Order (Alfisols) and on anthropogenic context. Research was conducted to

see the effect of the soil on GPR to detect unmarked graves. In order to asses the suitability of

GPR with the soil properties, two different frequency antennas (900-MHz and 500-MHz) were

compared during the survey. The soils from the site area are mapped as well developed Alfisols

(Thomas et al. 1985). These soils are classified as a Pedro- Jonesville complex, with varying

depths of argillic horizon; which are so intermixed, that they cannot be separated at the scale of

mapping (Thomas et al. 1985). The marked graves are from the early twentieth century; several

unmarked graves are located within proximity of only a few meters. This site addressed several

obj ectives of the study: the application of GPR to verify the existence of a clandestine grave

while meeting the criteria of a specific Florida soil Order.

Soil Physical Analysis

Particle-size distribution of native soils at this site indicated soil texture ranging from fine

sand to clay textures. The Newberry cemetery natural soils (NCNS), native Arenic Hapludalfs,










were approximately 91% medium to very fine sand throughout the A and E horizons, with less

than 4% silt or clay. The Ap horizon had a silt content of 3.5 % with a decrease to 2.3% in the E

horizon. The amount of clay increased from < 4% in the Ap and the E horizons to >21% in the

Bt horizon. The silt content increased to < 6% in the Bt horizon for the native soils.

The particle-size distribution of the Newberry cemetery anthropogenic soils (NCAS)

ranged from medium grain sand to a clay fraction. The mixed horizons of the NCAS varied

widely in particle-size distribution. Soils from suspected surveyed graves were ranged

approximately from 86% to 91 % medium to very fine sand in the Ap horizon, with ranges of

4%-6% silt and 3%-6% clay. Soils from the altered El horizon (45-60 cm) had a backfill

scattering that ranged from 11.6% to 42.2% clay. (Figure 4-1).





45
40-
35-
30 o-% Clay
251 (Anthropogenic)
e, 20-
[L15 -m-% Clay
10 V (pedogenic)


0-15 (A) 45-60 (E1) 83-98(E2) 130-142(Bt)
Depth (cm)

Figure 4-1. Depth distribution of total clay content of natural transectt 17) and anthropogenic
transectt 14) soils at the Newberry cemetery.

Medium to very fine sand ranged from 64.2% to 85.1% and the silt content was 5%-6% in the

soil from the anthropogenic altered E horizon. Clay content increased in the associated Bt

horizon in the anthropogenic soil to 41.2%. When the percentage of clay is compared with depth,

clay increased in the NCAS at 45-60 cm along transect 14










Soil Chemical Analysis

The acidity of the NCNS ranged from a pH 5.2 to 8.5 (Appendix C-1). The NCNS along

transect 17 had a pH range of 5.2 to 6.1, with lower pH values located in the E horizon and

higher pH associated with A and Bt horizons. The Bt horizon had 10% regolith, indicating

underlying limestone. Soil acidity was contingent upon depth to limestone. Soil samples

collected near the limestone had pH values higher than any other horizon.

The NCAS had a wide pH range of 5.3 to 8.4 across the site area (Figure 4-2). Cemetery

samples had a discernible pattern of pH change based on sample depth. Soil pH increased along

transect 14, from 7.5 at the Ap horizon (15 cm) to 8.4 at a depth of 115 cm. The pH range for

soils sampled from suspected burials is higher due to the mixing of soil horizons, including

limerock and possible diagenesis of bone.





6 -o pH Anthropogenic
5 -1 soil
4 -( -m- pH Natual soil





15 45 85 115 145
Depth (cm)
Figure 4-2. Depth distribution of Transect 14 pH values and Transect 17 pH values at the
Newberry cemetery

The OC content of NCNS, determined by Walkley-Black digestion, was < 5 g/kgl in all

horizons (Table 4-1). The OC content decreased with depth until the Bt horizon. The NCNS Ap

horizon contained 2.61 % OC. This decreased in the E horizons to approximately 0.35 %

average. The OC content increased in the NCNS Bt to 1.25%. Anthropogenic soil OC content









was similar with the natural soils. The Ap horizon contained 2.8 % OC. A decrease in the E and

Bt horizon occurred to approximately 0.48% and 0.42 % of OC respectively.

The EC (EC) of the NCNS had low values (Table 4-1), ranging from 0.74 to .04 ds/ml

The EC values decreased with depth in the NCNS E horizon, .04 to .06 ds/m- The Bt horizon's

highly conductive clay media had the highest values of .41 ds/m l. The EC of the anthropogenic

soils had a higher range of values. The values for the Ap horizon were .74 ds/m- The EC values

for the E/Bt mixed horizons had a smaller decrease to .35 ds/ml on average.

Table 4-1. Selected soil chemical analysis of the Newberry Cemetery natural and anthropogenic
soils along transects 14 and 17. The EC (EC), extractable (Ext.), Organic carbon
(OC), of the Newberry cemetery natural soils (NCNS), and Newberry cemetery
anthropogenic soils (NCAS).
Soil Depth Horizon EC Ext. P Ext.Ca Ext. Mg OC
(cm) ds m-1 mg/kg mg/kg mg/kg %
NCNS 0-15 Ap 0.28 12.72 188.72 28.06 2.61
Transect 45-60 El 0.06 9.88 60.13 3.94 0.48
17 85-100 E21 0.06 11.96 12.69 3.5 0.23
116-131 E22 0.04 7.1 8.56 1.51 0.23
145-160 Bt 0.41 40.12 1209.4 21.22 1.25
NCAS 0-15 Ap 0.74 32.1 2693.1 53.2 2.8
Transect 45-60 El 0.4 189.8 2141.4 17.2 0.48
14 83-98 E2 0.28 36.6 1167.7 13.1 0.48
115-130 Bt 0.38 80.5 978.6 27.7 0.42



Ext P contents in the NCNS (Table 4-1) ranged from 7.1 to 40.12 mg/kg-l and increased in

depth except between the Ap and El horizons. The Bt horizon had a four-fold increase of Ext P

than from the overlying El and E2 horizon. Overall, the NCAS contained greater values of

extractable P than the NCNS (Table 4-1). Ext P content increased markedly in the El horizon

and reduced to lower values in both the overlying Ap and underlying E2 horizons. The greatest

values of Ext P occurred where the mixing of soil horizons was most pronounced. Ext P content

increased again in the Bt horizon, more than twice as much than the overlying E2 horizon.









Concentrations of Ext Ca in the NCNS ranged from 8.5 to 1209.4 mg/kg with the lowest

value occurring in the E2 horizon and the highest amount in the underlying Bt horizon (Table 4-

1). Proximity of the underlying limerock to the Bt horizon facilitates increased values of Ca in

NCNS. The Ap horizon contained higher values of Ca than that of the underlying El horizon.

Overall values of Ca in the anthropogenic soils were significantly higher in all recorded depths.

Ca content for the NCAS samples were at the high end of the range of all soils in the site area.

Unlike the NCNS, the overall Ca values decreased with depth; both the natural and

anthropogenic soil samples had similar Ca values in the Bt horizon.

Both the natural and anthropogenic soils contained comparable amounts of Mg throughout

(Table 4-1), with the highest values occurring in the Ap horizon and lowest in the El and E2

horizons. The content of Mg in both soils increased in the Bt horizon from overlying El and E2

horizons.

Soils chemical analyses were conducted to determine the differences between natural and

anthropogenic soils. The NCNS have low values of P, and Mg; while increased Ca values are

associated with depth to limestone. The NCAS have increased values of P, Mg, and Ca from

suspected buried remains. The means of these three elements from natural soils were compared

to those of anthropogenic soils by calculating t-tests (Appendix E)

Samples were collected from both natural and anthropogenic soils at the Newberry site

area. The NCNS from the site were used as the control for determination of potential natural

soils. The NCNS from the site area were lower in extractable P concentrations than from the

anthropogenic soils (t = -3.04, p = 0.01019) (Appendix E-1). The mean average for native soils

was 20.5 mg/kg, while the NCAS had a mean average of 68.4 mg/kg. The overall Ca values of

both the NCNS and NCAS were significantly different. Mixing of the anthropogenic soil









horizons fundamentally altered the concentrations of Ca (t = -3.92, p = 0.00153) (Appendix E-1).

Variability of Ca values throughout the soil horizons is reflected in the standard deviation that is

more than double the NCNS. Concentrations of Mg did change between the NCNS and the

NCAS (t = -2.53, p = 0.09874) (Appendix E-1), but not to the extent of the P and Ca

concentrations.

GPR-Soil Results for Newberry Cemetery

The 500-MHz antenna

Data acquisition of both NCNS and the NCAS soils with the GPR using the 500-MHz

antenna created approximate profiles with distinctive reflections caused by contrasting soil

properties. The NCNS has a planar stratification with occasional voids from the karst subsurface

(Figure 4-3). Multiple, continuous contrasting layers in the NCNS soil represent the presence of

an argillic (Bt) horizon. The depth to argillic horizon in Figure 4-3 is approximately 0.9 to 1.1 m.

Soils associated with Typic and Arenic Hapludalfs are often not stratigraphically homogenous.

Bioturbation, such as animal burrows and tree roots, will frequently alter soil horizons.

Processing steps for the horizontal and vertical correlation of the NCNS and NCAS

profiles include marker interpolation for distance (meters) and static correction time cuts for the

removal of antenna ringing and velocity adaptation (Figure 4-3a). The lines superimposed on the

GPR profiles in Figure 4-4 are manual velocity adaptation picks displayed to highlight the

argillic horizon. After the soil surface and horizontal alignment was determined, a background

filter was applied to the transect profile. In order to accentuate and highlight a horizon interface,

spectral whitening was applied to the GPR profiles when necessary (Figure 4-3b).

A discernable difference in interpreting GPR profiles is from the color scale; this is often

the preference of the GPR operator. However by viewing multiple color scales, subtle images

may become enhanced. In the anthropogenic soils, differences in color scale assisted in the









overall interpretation. The profiles viewed in Rainbow 2 color scale from Figure 4-3a is shown in

Grey 1 color scale (Figure 4-3c).

Energy decay was a final processing step chosen for select GPR profiles to augment data

interpretation. The process extracts an energy decay curve of the line and applies the inverse of

this function on the data. By activating this function a gain curve in the time direction (y-axis) is

applied on the complete profile based on the mean amplitude decay curve. This step was

primarily for highlighting the presence or absence of altered, heterogeneous anthropogenic soils

(Figure 4-4). A pick was inserted into selected profiles to highlight subsurface amplitude value

changes. Such changes included the interface of overlying horizons and the argillic horizon

(Figure 4-3a, c).

The GPR profiles of the NCAS produced distinct non-point source anomalies in both the

E2 and Bt horizons. Due to the soil properties associated with the anomaly and stratigraphic

break of the horizons, radar scatter occurred in the GPR profile (Figure 4- 4a). A low-amplitude

reflection with little or no energy returned to the 500-1VHz antenna. This is demonstrated with

the absence of pronounced horizontal banding within the anomaly. Application of specific

processing procedures may either highlight or mask the selected feature. The processing step of

energy decay enables the operator to both highlight the grave and the backfill overburden (Figure

4-4b). With the application of spectral whitening, used for the NCNS profiles, the subtle image

of overburden is less pronounced (Figure 4-4c). GPR profiles with Grey 1 color scale augment

energy decay and spectral whitening processing features while reducing background noise

(Figure 4-5).











DISTANCE [MIETER]
8 9 10 11 12 13 14 15 16 17 15 19


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lessened depth of penetration. Radar signals were affected by both the type of anomaly and

depth. Coherent signals were attenuated with specific anthropogenic features.

The 900-MHz antenna was also affected by the depth to the argillic horizon. The depth of

the argillic horizon influenced the higher frequency antenna. On many transects the argillic

horizon was barely visible, or not detected using the 900-MHz antenna (Figure 4-6), but was

strongly evident with the 500-MHz antenna (Figure 4-3).

DISTMNCE *ETER]
OT1 20O


DISTANCE pETER]


Figure 4-5. Ground-penetrating radar profile of anthropogenic altered Arenic Hapludalf using
the 500-MHz antenna along transect 14. A) Filtering of horizontal banding and
background clutter is enhanced in Gray 1 color scale. B) Overburden is more
prominent when the energy decay processing step is applied in the Gray 1 color scale.
C) Note the very low amplitude reflection at the 9.5 to 12 m transect range is more
discernable when the Gray 1 color scale is used.










DISTRACE[MUETEF]
10 20


DIsTarrcE[MUETER]


Figure 4-6. Ground-penetrating radar profile of natural Arenic Hapludalf using the 900-MHz
antenna along transect 17. Velocity adaptation pick is inserted to highlight the argillic
horizon. A) Filtered profile reduces horizontal banding. The argillic horizon is less
discernable than from the 500- MHz antenna. B) Spectral whitening step is added to
filtered profile, highlighting the Argillic horizon. C) Filtering with spectral whitening
process combined with gray scale reduces horizontal banding significantly.

Anomalies detected by the 900-MHz antenna from the NCAS along transect 14 (Figure 4-7) are

discernable with post-processing procedures. Filtered profiles with energy decay processing

applied are more discernable than with just the filter alone; both with Gray 1 and Rainbow 1

color scales (Figure 4-6 b, c). Even filtered, numerous micro-reflections are evident throughout

the GPR profile. This background 'noise' may draw focus from subtle sub-surface features.












OIST~CE ~UIEIER]
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A I =

i
8:5
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'= -
:i=~i

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f"iv~ r- ~c;


DISTANCE IUETER]
10


DISTANCE IUETER]


Figure 4-7. Ground-penetrating radar profile of anthropogenic Arenic Hapludalf using a 900-
IVHz antenna along transect 14. A) Background filter reduces subsurface
discontinuities throughout the profile. Low amplitude reflection from a feature is
discernable between the 9.5 to 12 m range along transect from 0.5 to 1.6 m in depth.

B) Energy decay processing step is added to background filtering, highlighting the
scattering effect of low amplitude reflections. Overburden is discernable overlying

grave. C) Energy decay with background filtering using Gray 1 color scale further
reduces subsurface discontinuities and isolates the overburden and underlying grave.









Oakland Cemetery

The Oakland cemetery is located south of Lake Apopka in western Orange County,

Florida. This site was selected for the native soils (Entisols) and the anthropogenic context

(cemetery). The soils from the site area are mapped as both Entisols and Ultisols (Doolittle and

Schellentrager 1989). These soils are classified as a Candler-Apopka complex; the mapped areas

consist of generally 66% Candler soil (Entisols) and similar soils, with about 31% Apopka soil

(Ultisols) and similar soils. This soil complex is too mixed to be mapped separately (Doolittle

and Schellentrager 1989). The marked graves are from the late nineteenth to early twentieth

century; several unmarked graves are located within proximity of the existing cemetery. This

site, similar to the Newberry cemetery, addressed several objectives of the study: the application

of GPR to verify the existence of a clandestine grave while meeting the criteria of a specific

Florida soil Order.

Soil Physical Analysis

Particle-size distribution of Oakland cemetery natural soils (OCNS) was dominated in all

samples by the medium grain to very fine grain sand (Appendix A). The soil data were compared

to the information from the Orange County Soil Survey (Doolittle and Schellentrager 1989). The

site area has been mapped as Candler and Apopka-Candler complex. Candler soils are a

hyperthermic, uncoated Lamellic Quaritzipsamments. The Candler soils series consists of

excessively drained soils, an ochric epipedon, approximately 90% medium to very fine sand in

the A and C horizons, and less than 3% silt and 2.5% clay. The ochric epipedon had an average

silt content of 1.8%. The Candler series at the Oakland cemetery has clear, wavy lamellae at

approximately 1.0 to 1.2 m in depth. The amount of clay content increased from < 1.2% in the

Ap horizon, to 2.5% in the C3 horizons in association with the lamellae. At the Oakland site

area, the Candler soil series is associated with the Apopka series. Apopka soils are loamy,









siliceous, hyperthermic Grossarenic Paleudults. These two soils are morphologically very similar

in the upper 1.5 m. The Apopka series has an argillic horizon within 2.0 m of the surface.

Physical soil analyses from the site determined the absence of a Bt horizon, with the default

classification being a Candler soil series. Further discussion of taxonomic and morphological

classification of the Oakland cemetery soil will be addressed in Chapter 5 and Appendix A.

Oakland cemetery anthropogenic soils (OCAS) were dominated in all samples by medium

to very fine sand. Associated with OCNS, the mixed horizons of the altered soils did not change

noticeably in particle-size distribution. Particle-size distributions of the OCAS horizons were

dominated in all samples by the sand fraction, with a range of 95.1 to 97.9%, with low values of

silt (< 2.7%) and clay (< 2.6%). Potential surveyed graves displayed no significant change in

physical properties from the OCAS.

Soil Chemical Analysis

The acidity of the Oakland cemetery soils ranged from a pH 5.9 to 7.1 (Figure 4-8). The

OCNS had a pH range of 4.9 to 5.3, with lower pH values located in the Ap horizon and higher

pH associated with Cl horizons. Soil acidity for the OCNS was not significantly variable, with a

pH range of 4.9to 5.3 of all horizons. Orange groves are located within 75 meters upslope on the

east and north sides of the site area (Figure 2-3). This tertiary influence on pH and other

chemical analyses will be discussed in the next chapter.

The OCAS had a pH range of 6.0 to 7.2 across the site area. Cemetery samples had a

pattern of pH change based on sample depth. Soil pH increased varied from 6.0 in the lower C

horizon (85cm) to 7.2 (50 cm) at two grave samples (Figure 4-8). The pH range for soils sampled

from suspected burials is higher due to the mixing of soil horizons, including possible diagenesis

of bone.
















I- pH Antropogenic soil
-m- pH natural soil





15 50 85 120
Depth (cm)

Figure 4-8. Depth distribution of pH values for Transect 2 at the Oakland cemetery.

The OC content of OCNS, determined by Walkley-Black digestion, was < 2 % in all

horizons along transect 2 (Table 4-2). The OC from the OCNS samples decreased with depth

until the C3 horizon. The Ap horizon contained of 1.32 % OC. This decreased in the Cl horizon

to 0.1 %, C2 horizon to 0.16 % and to a 0.29 % in the C3 horizon. The OCAS OC content was

slightly higher than native soils in the Cl horizon and C2, with lower values in the C3 horizon.

The Ap horizon in the OCAS had lower values of OC, with 0.55 %. A decrease in the

anthropogenic Cl horizons occurred to approximately 0.42 % of OC, with 0.48 % in the C2

horizon. The OCAS C3 horizon had lower values than the OCNS C1, C2 horizons with

approximately 0.03 % of OC.

The EC (EC) of the OCNS had low values from transect 2 (Table 4-2), ranging from 0.34

to 0.06 ds/m- The EC values in the Ap horizons of the OCNS were approximately 0.34ds/m l,

and decreased with depth in the Cl horizons, C2 horizons and C3 horizons from .08 to .06 ds/m

1. The EC of the OCAS had a lower range of values. The EC mean average for the Ap horizons

was .14 ds/m- The EC values decreased to .14 ds/m-l in the Cl horizons, .06 ds/m-l in the C2

horizons and increased slightly to.26 ds/m-l in the C3 horizons.









Ext P content in the OCNS (Table 4-2) from transect 2 ranged from 12.8 to 4.29 mg/kg-l

and was variable in depth between the C1, C2 and C3 horizons. The Ap horizon had a value of

12.8 mg/kg- with the C3 horizons having the next highest overall Ext P concentration at 10.41

mg/kg- The OCAS contained greater values of extractable P than the OCNS (Table 4-2). Ext P

content of anthropogenic soils increased markedly in the Ap, with 58.84 mg/kg- with 70.48

mg/kg-l and in the Cl horizon. Lower values of Ext P occurred in C2 with 6.87 mg/kg- and 4.69

mg/kg-l in the C3 horizon. The greatest values of Ext P occurred at a depth of 0-50 cm, where

the mixing of soil horizons was most pronounced.

Concentrations of Ca in OCNS from transect 2 ranged from 26. 14 to 65.45 mg/kg-l with

the lowest value occurring in the lower C2 horizon and the highest amount in the Ap (Table 4-2).

Ext Ca decreased with depth until the C3 horizon (13 5 to 150 cm) with a value of 46.3 8 mg/kg- .

Overall values of Ext Ca in the OCAS were significantly higher in the upper 0.5 m. Ext Ca for

the OCAS ranged from 148.29 mg/kg-l in the Cl horizon to 10.92 mg/kg-l in the C3 horizon.

The OCNS contained lower overall values of Mg than the anthropogenic soils. (Table 4-2).

Ext Mg in OCNS ranged from 25.21 to 9.49 mg/kg- with higher values in the upper 0.5 m and

the lowest values occurring between 0.85 to 1.00 m. Ext Mg in the anthropogenic soils decreased

with values of 14.91 mg/kg-l in the C2 horizon and to 6.01 mg/kg-l in the C3 horizon.

Soils chemical analyses were conducted to determine the differences between natural and

anthropogenic soils. The OGSN have low values of P, Ca, and Mg. Anthropogenic soils have

increased values of P, Mg, and Ca from suspect buried remains. These means of these three

elements from NCNS were compared to those of the NCAS by calculating t-tests









Table 4-2. Selected values of chemical properties of the Oakland Cemetery natural and
anthropogenic soils along transect 2. The EC (EC), extractable (Ext.), Organic carbon
(OC), Oakland cemetery natural soils (OCNS), Oakland cemetery anthropogenic soils
(OCAS).
Soil Depth Horizon EC Ext. P Ext.Ca Ext. Mg Org. C
(cm) ds ml mg/kg mg/kg mg/kg %
OCNS 0-15 Ap 0.34 12.8 65.45 25.21 1.32
Transect 35-50 Cl .08 8.02 47.49 12.46 0.1
2 85-100 C2 .06 4.29 26.14 9.49 0.16

135-150 C3 .06 10.41 46.38 13.05 0.29

OCAS 0-15 Ap 0.14 58.84 127 25.21 0.55
Transect 35-50 Cl 0.14 70.48 148.29 20.22 0.42
2 85-100 C2 0.06 6.87 29.91 14.91 0.48
135-150 C3 0.26 4.69 10.92 6.01 0.03


Samples were collected from both natural and anthropogenic soils at the Oakland cemetery

area. The OCNS from the site were used as the control for determination of suspect

anthropogenic soils. The OCNS from the site area were lower in extractable P concentrations and

variability than from the anthropogenic soils (t = -2.62, p = 0.1853) (Appendix E-2). The mean

for OCNS was 8.26 mg/kg, while the impacted soils had a mean of 34.4 mg/kg. The overall Ca

values of both the OCNS and OCAS were markedly different. Mixing of the anthropogenic soil

horizons altered the concentrations of Ca (t = -1.89, p = 0.2329) in the upper 0.5 m. Variability

of Ca values is limited to the upper soil horizons; this is reflected in the standard deviation that is

more than double that of the natural soils. Concentrations of Mg did change significantly

between the OCNS and OCAS (t = -1.69, p = 0.1625) (Appendix E-2).

GPR-Soil Results for Oakland Cemetery

The 500-MHz antenna

The OCNS has a homogenous matrix with little variation in physical properties (Figure 4-

9). The Candler series at this site has clear, wavy lamellae at approximately 1.0 to 1.2 m in depth









that is evident in the GPR profile with the 500-MHz antenna. Bioturbation, such as animal

burrows and tree roots, will be evident at depths less than 2 meters in the OCNS. Anomalies at

depths greater than two meters often entail targets larger than most bioturbation. Both OCNS and

OCAS GPR profiles are along the same transect.

Identical processing steps for the horizontal and vertical correlation of the GPR profiles at

the Newberry cemetery were used for the Oakland cemetery. This included marker interpolation

for distance (meters) and static correction time cuts for the removal of antenna ringing (Figure 4-

9a). After the soil surface and horizontal alignment was determined, a background filter was

applied to the transect profile. In order to accentuate and highlight a horizon interface, spectral

whitening was applied to profiles when necessary (Figure 4-9c). This step was primarily for

highlighting the presence or absence of altered, heterogeneous anthropogenic soils, but was also

used for the homogenous nature of the soils at the site area. Spectral whitening decreased the

hyperbolic tail associated with the anomalies in transect 2

The GPR profiles of anthropogenic soils at the Oakland cemetery produced distinct point

source anomalies in both the Cl and C2 horizons. Due to the soil properties associated with the

elongated and suspect graves, noticeable reflection hyperbolas occurred in the GPR profile

(Figure 4-9a). Medium to high-amplitude reflections with significant energy returned to the 500-

MHz antenna, enabling a distinct signal return separate from the surrounding matrix. This is

demonstrated with the presence of pronounced horizontal banding within the anomaly.

Background filters allow for a clearer image of an already distinct anomaly. With the application

of spectral whitening, the image becomes more pronounced (Figure 4-9c). A pick was inserted

into selected profiles to highlight subsurface amplitude value changes. Such changes included

the start of the lamellae from 1.0 to 1.5 m in depth.










DISTANCE hnETER]
10 20 30






01T ETR




E~ 07





Ol:T 0 10 20 30







Fiur 4-9. Grudpntaigrdrprfl sn h 0-2 atnawt w upc




bacgrondfilerignote hencrese conras ofsspectgrae and\ te reucio
of- hprboli tal )Bcgon itri pled nen os srmvdadGa
t colo scl sue.Cnrs i nacdadhprolcti sicesd















MFz anenna9 (Figurdee 4-9; wile thea inroieaused rsltion fromz athen 900-Hz atenn wasoffst










by shorter hyperbolic tails in processed profiles. The use of higher frequency antennas may limit

the operator to locating and interpreting anomalies at varied depths along a transect profile.

Anomalies detected by the 900-1VHz antenna from the anthropogenic soils along transect 2

maybe more discernable with post-processing procedures, but not necessary. Filtered profiles

with spectral whitening processing applied are no more discernable than with just the filter alone

(Figure 4-10 b); both with Gray 1 and Rainbow 2 color scales (Figure 4-10 a, c). Filtered, with

spectral whitening allows for less numerous micro-reflections throughout the profile. As with the

500-1VHz antenna profiles, velocity adaptation picks were inserted to the processed profiles to

highlight the lamellae from 1.0 to 1.5 m in depth (Figure 4-10).

Prehistoric Archeological Site

The prehistoric archaeological site is located in eastern Lake County, Florida on the

southwest shore of Lake Apopka. This site was selected for the study based on the both the soils,

(Inceptisol) and on the anthropogenic context (prehistoric). There are two soils are mapped with

the site area; a well-drained Orlando series (Inceptisol) and a very well-drained Entisols

classified as the Lake soil series (Furman et al. 1975). The Orlando series is the predominate soil

for this study. Two prehistoric archaeological components have been previously excavated in

this study area. Associated features within the prehistoric midden date as early as 1600 B.C.

(Austin 2006). This site addressed several objectives of the study: the application of GPR to

verify the extent of prehistoric anthropogenic influences while meeting the criteria of a specific

Florida soil Order.










DIsTaNlCE [FlER]n


"DSTNC [MBER]04



20-




DIsTaNCE [IunlER

10 00a:~ o


r016
10 02


C os
10l!c' 05;7 ,5 1





Figure 4-10. Ground-penetrating radar profile using the 900-MHz antenna of two suspect graves
in a Lamellic Quartzipsamment. A) Background filter is applied and antenna noise is
removed. Horizontal banding is still prevalent. B) Spectral whitening processing step
is added to background filtering, note the increased contrast of anomalies and the
reduction of hyperbolic tail. C) Background filter is applied, antenna noise is removed
and Gray 1 color scale is used. Contrast is enhanced and hyperbolic tail is increased.

Soil Physical Analysis

All horizon designations for this site were described morphologically and subdivided for


sampling purposes. The primary numerical suffixes are denote subdivisions within a master

horizon; e.g., Al, A2, C1, C2, and C3. Secondary numerical suffixes denote the sampling

subdivision within the horizon modifier. Particle-size distributions of the prehistoric

archaeological natural soils (PANS) at this site were dominated in all samples by medium to very

fine sand (Appendix A). The soil data was compared to the information in the Lake County Soil









Survey (Furman et al. 1975). The soil survey area has been mapped as a well-drained sandy,

siliceous, hyperthermic Psammentic Dystrudepts, with an umbric epipedon, approximately

93.5% coarse to fine sand throughout the A and C horizons, and less than 1% silt and 5.7% clay.

The umbric epipedon had an average silt content of 0.8% with a decrease to 0.3% in the C

horizon. The amount of clay content increased slightly from < 5.9% in the A horizon to 6.4% in

the C horizon.

Physical properties of the prehistoric archaeological anthropogenic soils (PAAS) at the

prehistoric site were very similar to the PANS. Both the PANS and PAAS had no morphological

differences in any of the horizons, except an A/C horizon at 0.9 to 1.05 m. The PAAS were

dominated with approximately 94.2% coarse to fine grain sands, less than 1% silt and 6.6% clay

in the A and C horizons. The silt content varied less than 0.7% among the A and C horizons.

Less than a 1% difference in clay content occurred among the A and C horizons in all

anthropogenic samples.

Chemical Analysis

The acidity of the all prehistoric site soils ranged from a pH 4.3 to 6.9 (Figure 4-11). The

PANS had a pH range of 4.3 to 5.5, with lower pH values located in the A horizon and higher pH

associated at a depth of 0.35 to 0.75 m. Soil acidity for the PANS was variable, with a pH range

of 4.4 to 4.6 below 0.75 m. Orange groves are located within 5 to 10 meters upslope on the west

side of the site area (Figure 2-6). This tertiary influence on pH and other chemical analyses will

be discussed in the next chapter.

The PAAS had a pH range of 6. 1 to 6.9 along selected GPR transects (Figure 4-1 1).

Samples had a pattern of pH change, increasing with sample depth. Soil pH increased from 6. 1 at

the surface (0-15 cm) to 6.9 at the base of the C horizon (1.8 to 1.95 m). The OC content of the

PANS, determined by Walkley-Black digestion, was < 2.5 % in all horizons (Table 4-3). In










general OC amounts decreased with depth. The Al horizon contained 2.4 g/kgl OC. This

decreased in the A2 horizon to approximately 1.32 %, with 0.34 % in the C horizons. The PAAS

OC content was slightly higher than native soils in the C horizon. The A horizon in the PAAS

had slightly lower values of OC (1.96%) than the PANS (Table 4-3). A decrease in the PAAS A2

horizons occurred to approximately 1.55 % of OC, with 0.44 % in the C horizons. The PAAS C

horizon had slightly higher values than the PANS C horizons.








5 -o- IpH (natural soils)
..4
-m- pH (anthropogenic
soilIs)



15 45 75 105 135 165 195
Depth (cm)

Figure 4-11. Depth distribution of pH values for transects at the prehistoric archeological site.

The EC (EC) of the PANS had values (Table 4-3), ranging from 1.36 to 0.04 ds/m-1. The

EC values in the Al horizons were approximately 1.36 and 0.62 ds/m-1, and decreased with

depth in the A2 horizons. The values in the C horizons were from 0.04 to .48 ds/m-1. EC of the

anthropogenic soils had slightly lower range of values. The EC values for the Al horizon was 0.4

to 0.28 ds/m-1. The EC values decreased to 0.26 to 0.22 ds/m-1 in the A2 horizons. The values

in the C horizons ranged from 0. 18 to 0. 14 ds/m-1. Overall values decreased with depth in both

the PANS and PAAS horizons. Ext P content in the PANS (Table 4-3) ranged from 343.2 to 70.9

mg/kg-1 and decreased in depth between the Al2 and C13 horizons. The Al2 horizon had

highest value of 353.5 mg/kg-1, with the C13 horizons having the lowest overall extractable










phosphorus concentration at 70.9 mg/kg-1. Anthropogenic soils contained much greater values

of Ext P than the PANS. Ext P content of anthropogenic soils increased markedly in the Al2 and

A21 horizons with lower values in C horizons.

Table 4-3. Selected values of chemical properties from natural and anthropogenic soils at
prehistoric archaeological site. The EC (EC), extractable (Ext.), Organic carbon (OC),
prehistoric archaeological natural soils (PANS), and prehistoric archaeological
anthropogenic soils (PAAS). Soil horizons subdivided for sampling depths.
Soil Depth Horizon EC Ext. P Ext. Ca Ext. Mg Org. C

PANS cm ds ml mg/kg mg/kg mg/kg %
0-15 All 1.36 278 310.4 28.4 2.4
30-45 Al2 0.62 343.2 353.3 36 1.62
60-75 A21 0.32 278 231.2 21.6 1.49
90-105 A21 0.38 203.6 112.6 13.3 1.1
120-135 C11 0.04 167.2 80.7 13.2 0.78
150-165 C12 0.6 78.4 39.9 10 0.13
180-195 C13 0.48 70.9 38.6 9.9 0.13
PAAS
0-15 All 0.4 1400.2 2085 81.4 2.07
30-45 Al2 0.28 1617 2278.1 80.9 2.27
60-75 A21 0.26 1633.5 2347.4 64.7 2.07
90-105 A22 0.22 759.2 801.4 37.4 0.65
120-135 C11 0.18 710 648.6 34.3 0.58
150-165 C12 0.18 449.2 379.5 28.8 0.39
180-195 C13 0.14 388.4 303.4 24.3 0.19

The greatest concentrations of Ext P occurred at a depth of 0.30 to 0.75 m with values of 1617

and 1633.5 mg/kg- Concentrations of Ext P in the anthropogenic C horizon were lower than the

overlying the soil horizons.

Concentrations of Ca in the PANS ranged from 353.3 to 39.9 mg/kg-l with the lowest value

occurring in the lower C horizon and the highest amount in the Al2 (Table 4-3). Ext Ca

decreased with depth. Overall values of Ext Ca in the PAAS were significantly higher in all

horizons. Ext Ca contents for the PAAS ranged from 2347.4 mg/kg-l in the A21 horizon to









303.48 mg/kg lin the C13 horizon. Similar to the PANS the overall Ca values decreased with

depth throughout all horizons.

The PANS contained lower overall values of Mg than the PAAS (Table 4-3). Ext Mg in

the PANS ranged from 36.04 to 9.9 mg/kg-1, with higher values in the Al and the lowest values

occurring in the C horizon. The concentration of Mg in the PAAS decreased with depth with

values from 81.4 mg/kg-1 in the Al horizons to 24.3 mg/kg-1 in the lower C13 horizons.

Native Quartzipsammentic Haplumbrepts from the site were used as the control for

determination of potential anthropogenic soils. Elevated overall concentrations of extractables P,

Ca, and Mg were present throughout the site area; the potential reason for such high values will

be covered in the following chapter. The PANS from the site area were much lower in Ext P

concentrations and variability than from the PAAS (t = -4.71, p = 0.00597) (Appendix E-3). The

mean for the PANS was 224.73 mg/kg, while the impacted soils had a mean of 994 mg/kg. These

values are quite high in both the PANS and the PAAS. The overall Ca values of both the PANS

and the PAAS were noticeably different. Concentrations of Ext Ca in all horizons (t = -1.72, p =

0.01706) (Appendix E-3) were distinct. Variability of Ca values is not limited to any soil

horizons; this is reflected in the standard deviation that is more than five fold that of the PANS.

Concentrations of Mg did change between the PAAS and the PANS (t = -0.541, p = 0. 109), but

not with the significance of both the Ext P and Mg.

GPR-Soil Results for the Prehistoric Archaeological Site

The 500-MHz antenna

The PANS has little variation in physical properties. The Orlando series at this site has a

clear, morphological horizon separation; this depth is evident in the 500-MHz antenna GPR

profile (Figure 4-12). Even in the PANS, punctuated human disturbances are clear throughout

this site area. The GPR profiles of the PANS are along different transects than the GPR profiles









of the PAAS, but run through active orange groves. The GPR transects of the PANS were

conducted upslope and away from the known archaeological site areas, which were situated

along the lake shore. The differences between GPR profiles of the PANS and PAAS are in

context to archaeological significance for this study. Both soils have been altered through human

activities; the difference is temporal instead of spatial and will be covered in the discussion

chapter.

Identical processing steps for the horizontal and vertical correlation of the GPR profies of the

previous sites were used for the prehistoric site. This includes marker interpolation for distance

(meters) and static correction time cuts for the removal of antenna ringing. After the soil surface

and horizontal alignment is determined, a background fi1ter was applied to each transect profie.

In order to accentuate and highlight a horizon interface, spectral whitening was applied to GPR

profiles when necessary. This step was primarily for highlighting the presence or absence of

altered, heterogeneous anthropogenic soils, but was also used for the homogenous nature of the

epipedon at this site.

The GPR profiles of both the PANS and PAAS produced distinct point source anomalies

and planar subsurface interfaces in both the A2 and C horizons. Due to the soil properties

associated with the elongated and perpendicular anomalies of subsurface irrigation lines,

noticeable reflection hyperbolas occurred in the GPR profile (Figure 4-13a). Medium to high-

amplitude reflections with significant energy returned to the 500-MHz antenna, enabling a

distinct signal return separate from the surrounding matrix.

With planar stratification in the soil horizons, removal of horizontal banding greatly

enhances any anomalies. Background filters also allow for a clearer image of an already distinct











anomaly. With the application of spectral whitening, images become more pronounced and non-


point source anomalies are highlighted (Figure 4-13c).

DISTANCE [MIETER]
0 10 20


A Horizon
10
D i"06 I



DISTACE [ETER



A~ Horizon on -


DISTANCE [MIETER]
10


Figure 4-12. Ground-penetrating radar profies of a natural Psammentic Dsystrudepts using the
500-1VHz antenna. A) Background fi1ter is applied and antenna noise is removed.
Velocity adaptation pick is inserted to highlight the C horizon. B) Spectral whitening
processing step is added to background filtering, note the increased contrast between
the A and C horizon. C) Background fi1ter is applied, antenna noise is removed and
Gray 1 color scale is used. Contrast is enhanced between the A and C horizon with
velocity adaptation pick is inserted.










DISTahce PRER]n
0 10 20
Irrigation Dine -

03


DISTA~CE nEER]


]|STANCE PETER]


Figure 4-13. Ground-penetrating radar profiles of an anthropogenic Psammentic Dsystrudepts
using the 500-MHz antenna. A) Background filter is applied and antenna noise is
removed. B) Spectral whitening processing step is added to background filtering, note
the increased contrast between the A and C horizon. C) Background filter is applied,
antenna noise is removed and Gray 1 color scale is used. Hyperbolic tail and contrast
between the A and C horizon is enhanced. Feature banding is highlighted with change
in color scale.


Varying color scales accentuate subtle changes within the GPR profile, allowing the

operator multiple views for data interpretation. A difference in interpreting GPR profiles when

subsurface variation is nominal, offers an advantage with specific sites. In the anthropogenic


soils at this site differences in color scale assisted in the overall interpretation of subsurface

features.











The 900-MHz antenna

The GPR profie of the PANS using the 900-MHz antenna exhibited no distinct reflections


from all horizons. Data acquisition of both PANS and the PAAS with the GPR using the 900-

MHz antenna created shorter wavelengths, thereby increasing resolution of radar images (Figure


4-14).

DISTANCE IAETER]
0 10 20

I~~l _1 4 Horznnn ji




DITN;pRR
,.10 20





DITNE MTR




10202
CL. -Or+Or- 1 er
10~~~- A oizn
-II:L I i E06



f ~SC Horizon 1
13
30 .l1 5






noise is furhe reovd C) Bakron 1ter is apied anea H znos isreovd




Figuran spectra whin-pntening randa Gray color sal iAs usmed.Futher contrat ips usomewhat




apparent. Contrast is enhanced between the A and C horizon with velocity adaptation
pick is inserted.











DISTANCE lulETER]


Irrivaton DiceFeature12
,r- ~132
14


DISTANCE [MIETER]
0 10 20
0 00

10
1'02
PC



Irrigation Dine Fealture r 1
30 1 5
s: :,;5; '.. 1,6,

Figure ~ ~ ~ ~ ~ ~ 3 4-15. Grudpnertn raa rflsoa nhooei smetcDytuet
using~~~~~~~~~~~~~~ th 0-Mzaten.A) Bckgon fite s plidan ntnaosei
reovd B) Spcrlwieigpoesigse saddt acgon trnnt

the~~~~~~~~~ inrese cotatbtenteAadChrzn.C akrudfle sapid
antnn nos srmvdadGa oo cl i sd yeblcti srdcdi







Thgue -5 GPRon-etrig a profiles of th ASpoie nl difuethratigrapic resoluntion Anystubetle

changes ing GPrflswthe 0~ ditnctiena refectirounsasd byte i cotastlieng soiln proerie s wr


aparntinthe anthrops ognic soil usieng the 900-M z antenona C (Figuren 4-1).The increased,






apresoltion from atheooi 900-M s antenna wa ofet by~ shotern hypeurboi tails ofthe irrigation ip









in processed GPR profiles of the PAAS. A pick was inserted into selected profiles to highlight

subsurface amplitude value changes. Such changes included the A and C horizon interface. A

suspected feature is located near the irrigation pipe; this might be associated with the excavation

of the pipe (Figure 4-15). This suspected feature is less prominent in the GPR profile using the

900-MHz antenna, then with the 500-MHz antenna.

Historic Archeological Site

The British Period occupation site is located in northeastern St. Johns County, Florida,

west Tolomato River. This site was selected for the study based on the both the soils,

(Spodosols) and on the anthropogenic context (historic). The two soil Orders mapped in the site

area are weakly to moderately developed Spodosols with associated Entisols; and are classified

as either Myakka/Immokalee (Spodosols) with Paola (Entisols) soils (Readle 1983). The

Immokalee series is the predominate soil for this study. The archaeological context of this site is

primarily the British Period (1763-1784 A.D.), with Spanish and prehistoric components

associated with the site area. This site addressed several objectives of the study: the application

of GPR to verify the extent of historic anthropogenic influences while meeting the criteria of a

specific Florida soil order.

Soil Physical Analysis

The particle-size distribution of the historic archaeological natural soils (HANS) at this site

was dominated in all samples by the medium to very fine sand fraction throughout (Appendix

A). The soil data was compared to the information from the St. Johns County Soil Survey

(Readle 1983). The sampled site area has been mapped as the Immokalee, sandy, siliceous,

hyperthermic Arenic Alaquods series with approximately 95% medium to fine sand in the Ap

and El, E2, and E3 horizons, with less than 2.5% silt and 3% clay. The underlying Bh horizon is

from 0.74-0.93 m, with 2.4% silt and 2.8% clay. The ochric epipedon had an average silt content









of 1.7% with a linear decrease to 0.9% in the E3 horizon. The amount of clay and silt content

increased slightly in the Bh horizon.

The historic site area has another associated soil, a hyperthermic, uncoated Spodic

Quartzipsamment. This soil is the St. Johns series and has very similar morphological

characteristics to the Immokalee. Due to the depth of water table, the St. Johns series may be

more closely relevant to the site. However, from a morphological interpretation, the Immokalee

series will be referred in this chapter as the dominant soil series.

The human impacted soils at the historic archaeological site were dissimilar to the native

Arenic Alaquods. The historic archaeological anthropogenic soils (HAAS) had soil color

differences, lower values and chroma (Appendix A-4) in the horizons El and E2 horizons from

0.2 to 0.45 m. The HAAS were dominated with approximately 93.7% medium to fine sands, with

values of less than 6.0% silt and 3.5% clay in the A, El, and E2 horizons. The Ap horizon had a

mean average of 3.4% silt and 0.9% clay. The El horizon, from 0.20 to 0.25 m, had a mean of

1.9% silt and 1.6% clay; while the underlying E2 horizon had 1.5% silt and 1.7% clay at 0.40 to

0.45 m below surface. Overall silt and clay values are elevated in the El and E2 horizons when

compared to the HANS.

Soil Chemical Analysis

The acidity of the all prehistoric site soils ranged from a pH 4.7 to 7.8 (Appendix C-4).

Representative samples were taken from a HANS transect and a HAAS transect (Figure 4-16).

The HANS had a pH range of 4.7 to 5.4, with lower pH values located in the E horizons and the

higher pH values associated with the Ap horizon. The HAAS had a higher pH range of 6. 1 to 7.8

across the site area (Appendix C-4). Samples had a pattern of pH change, increasing with

sample depth. Selected soil pH from transect 1 increased with 6.1 at the surface (0-5 cm) to 7.5

and 7.6 in the E horizons (20 to 45 cm) (Figure 4-16).

















5 1 -o ~pH (natural soils)
a.4-
-m- pH (anthropogenic
soilIs)



5 25 45 65 85
Depth (cm)

Figure 4-16. Depth distribution of selected pH values for transects at historic archaeological site.
Historic site data did not exceed 0.50 m.

The OC content of the HANS, determined by Walkley-Black digestion, was < 6 % in all

horizons (Table 4-4). The OC content decreased with depth in the El and E2 horizons, and

increased in the underlying E3 and Bh horizons. The Ap horizon contained 5.07 % OC. This

decreased to approximately 0.32 %, with 0.26 % in the El and E2 horizons. The Bh horizons

increased to 1.8 %. Both the PANS and anthropogenic soils did not differ significantly in the Ap

horizon. Anthropogenic soil OC content was higher than native soils in the El horizon.

Decreases in the anthropogenic E2 horizon occurred to approximately 0.64 % of OC, yet was

double that of the PANS E2 horizon with 0.25%.

The HANS had values of EC (Table 4-4), ranging from .42 to .02 ds/m- The EC values

in the Ap horizons had the highest PANS values with approximately .42 ds/m l, and decreased

with depth in the E2 horizons, and E3 horizons from 0.04 to 0.02 ds/m- A slight change

occurred in the Bh horizon to a value of 0.06 ds/m- The EC of the anthropogenic soils had

slightly higher range of values. The EC mean average for the Ap









Table 4-4. Selected mean values of chemical properties from PANS and anthropogenic soils at
prehistoric archaeological site. Electrical conductivity (EC), extractable (Ext.),
Organic carbon (OC), historic archaeological natural soils (HANS), historic
archaeological anthropogenic soils (HAAS).
Soil Depth Horizon EC Ext. P Ext. Ca Ext. Mg Org. C
(cm) ds m-1 mg/kg mg/kg mg/kg %
HANS 0-4 Ap 0.42 14.3 7.4 47.6 5.07
4-16 El 0.02 1.1 5.1 3.4 0.32
16-46 E2 0.04 1.2 3.2 2.1 0.26
46-74 E3 0.02 1 3.5 1.4 0.26
74-93 Bh 0.06 27.8 23.4 8.7 1.8
HAAS 0-5 A 0.80 64.3 759.8 130.1 4.49
20-25 El 0.42 383.2 1390.8 50.9 1.28
40-45 E2 0.14 130.8 339.7 9.8 0.64

horizons was 0.80 ds/m- The EC mean values decreased to 0.42 ds/m-l in the El horizons, and

0.14 ds/m-l in the E2 horizons. Overall values decreased with depth in both the PANS and

anthropogenic soil horizons in the upper 0.5 m.

The HANS had Ext P contents that ranged from 1.1 to 27.8 mg/kg-l and decreased in depth

from the Ap to E3 horizons. In the Bh horizon the concentration of Ext P increased. The Ap

horizon had a value of 14.3 mg/kg- with the values stabilizing in the El, E2, and E3 horizons at

1.1 to 1.2 mg/kg- The highest concentrations occurred in the Bh horizon with mean values of

27.8 mg/kg- The HAAS contained more Ext P than the HANS (Table 4-4). Extractable P

content of anthropogenic soils increased distinctly in all horizons. The greatest value of

extractable P occurred in the E2 horizon with 383.2 mg/kg- where morphological alteration was

most prominent. Concentrations of Ext P in the HAAS for the A horizon was 64.3 mg/kg-l and

130.8 mg/kg-l for the E2 horizon.

Concentrations of Ext Ca in the HANS ranged from 3.2 to 23.4 mg/kg-l with the lowest

value occurring in the E2 and the highest amount in the Bh horizon (Table 4-4). Concentrations

of Ext Ca decreased with depth from the Ap horizon (7.4 mg/kg- ), until the Bh. Overall values

of Ext Ca in the HAAS were significantly higher in all horizons. Concentrations of Ext Ca









content for the anthropogenic soil ranged from a low of 339.7 mg/kg-l in the E2 horizon to

1390.8 mg/kg- soils in the El horizon. The Ap horizon also had an elevated concentration of

extractable Ca in the HAAS.

The HANS contained lower overall values of Mg than the HAAS. (Appendix C-4).

Concentrations of Ext Mg in the HANS ranged from 1.4 to 47.6 mg/kg- with higher values in

the Ap and the lowest values occurring in the E3 horizon. The concentration of Ext Mg in the

HAAS also decreased with depth with values from 130.1 mg/kg-l in the Ap horizons to 9.8

mg/kg-l in the E2 horizons (Table 4-4).

The HANS from the site were used as the control for determination of suspected

anthropogenic soils. The HANS from the site area were much lower in extractable P, Ca and Mg

concentrations and variability than from the anthropogenic soils (Appendix E-4). Extractable P

values differed in the HANS than from the HAAS (t = -2.97, p = 0.0934) (Appendix E-4). The

mean for the HANS was 9.65 mg/kg, while the HAAS had a mean of 85.6 mg/kg. The overall Ca

values of both the HANS and the HAAS were significantly different. Concentrations of Ca in all

horizons (t = -2.87, p = 0.0601) varied between soils. Variability of Ca values is reflected in the

standard deviation that is more than ten fold that of the HANS (Appendix E-4). The overall

concentrations of Mg did change between the HAAS and the HANS (t = -1.71, p = 0. 1751i), but

not with the significance of Ext P and Ca.

GPR-Soil Results for the Historic Archaeological Site

The 500-MHz antenna

The natural soil of the HANS has a diverse matrix with variation in physical properties

between the E and Bh horizon (Figure 4-17). The Immokalee series at this site has clear, abrupt

spodic horizon at approximately 0.74 to 0.93 m. This Bh horizon is evident in the GPR profile

from the 500-MHz antenna. Bioturbation, such as tree roots, are evident at depths less than 1









meter (Figure 4-17). The GPR profiles of the HANS and the HAAS are along different transects,

but with 25 m of each other. The length of the GPR transect for the HANS is 3 meters; while the

GPR transects of the HAAS are 2 to 3 meters in length. The length of the anthropogenic GPR

transects were based on the size of excavation unit coverage. In the GPR profile, wall fall debris,

wall footer and a floor from a structure are highlighted in Figures 18 and 20.

Identical processing steps for the horizontal and vertical correlation of the GPR profiles for

the natural soils and the anthropogenic soil at the Newberry cemetery, Oakland cemetery and the

prehistoric site were used for the historic site. This includes marker interpolation for distance

(meters) and static correction time cuts for the removal of antenna ringing (Figure 4-17a-c). In

order to accentuate and highlight the Bh horizon interface, spectral whitening was applied to

profiles when necessary (Figure 4-17b). This step was primarily for highlighting the presence or

absence of the altered, heterogeneous HAAS, but was also used for the homogenous nature of

the soils at the site area. A pick was inserted into selected profiles to highlight subsurface

amplitude value changes. Such changes included a Bh horizon and wall footer. The GPR profiles

of anthropogenic soils at the Historic site produced distinct planar anomalies in both the El and

E2 horizons. Medium to high-amplitude reflections with significant energy returned to the 500-

MHz antenna, enabling a distinct signal return separate from the surrounding matrix. This is

demonstrated with the presence of pronounced horizontal banding within the anomaly

Background filters allow for a clearer image of an already distinct anomaly. With the application

of spectral whitening, any contrast between archaeological features and the overlying soil is

enhanced (Figure 4-18c). The use of Gray 1 color scale enables the operator alternate data

interpretation.