ANDSCAPE L INES

INTRODUCTION

Geophysical survey techniques indirectly measure the presence of resources concealed within the earth’s subsurface as a result of geologic

processes or human disturbances. Geophysical survey techniques detect

subsurface contrasts, including mass-density relationships, ionic or electrical

potentials, magnetic susceptibilities, and elemental decay. The surveys can

reveal the location of archeological resources and lead to their identification.

Geophysical survey equipment is used to investigate buried prehistoric

and historic structures and artifacts. The use of geophysical survey

equipment and computer aided interpretation has increased the accuracy of archeological surveys to the point where potentially destructive,

random excavations can be minimized.

Geophysical survey techniques cannot positively identify a buried cultural

resource, but they can provide data for interpretation from which strong

inferences can be made. Geophysical surveys use remote sensing

techniques, which examine earth features from a distant platform

situated above a target area and usually employ high altitude aircraft or

satellites. From a platform situated on or just above the earth’s surface,

geophysical survey equipment remotely sense earth features in a target

area located beneath the earth’s surface. APPLYING GEOPHYSICAL SURVEY TECHNIQUES TO CULTURAL LANDSCAPE RESEARCH

Geophysical survey techniques are either passive or active. Passive

techniques measure naturally occurring earth-related processes, such

as the earth’s electromagnetic or gravitational field. Magnetometry is

a passive geophysical survey technique. Active techniques involve

6

transmitting an electrical, electromagnetic, or acoustic signal into the

Geophysical Survey Techniques
2 L A N D S C A P E L I N E S

subsurface. Interaction of the input signal with

subsurface materials produces a modified return

signal that can be measured. A familiar, amateur

active technique is the metal detector. Other

active geophysical techniques include ground

penetrating radar, electrical resistivity, and electromagnetic conductivity.

Geophysical techniques were used in an archeological survey of Virginius Island, a nonextant, nineteenth

century industrial community in Harpers Ferry

National Historical Park. (See Figure 1.) Geophysical

services were contracted to determine the location

of twelve, nineteenth century residential structures

and their associated outbuildings, buried within four

acres of river terrace landscape. (See A Guide to

Cultural Landscape Reports: Appendices, “Appendix

J: Project Agreements.”) The general location of

these residences was derived from historical documentation, maps, and photographs, but the precise

location of the outbuildings and their yards was

unknown. The project agreement for the geophysical survey specified ground penetrating radar and

electromagnetic conductivity, but allowed for the

possibility of using additional techniques to verify the

location of a feature. The results of the geophysical

survey led to the excavation or “ground-truthing” of

specific sites to produce an accurate site plan of

Virginius Island. Results of the survey facilitated

development of a treatment plan, which included

an interpretive program. (See Figures 2 and 3.)

Passive Geophysical Survey Techniques

Passive geophysical survey techniques measure

naturally occurring, local, or planetary fields

created by earth processes. Passive techniques

IMPLEMENTATION AND LIMITATIONS OF A

GEOPHYSICAL SURVEY

Successful implementation of a geophysical survey depends

on the following:

• A comprehensive survey design that specifies the set of

techniques chosen for a survey (multiple techniques are

requisite for a thorough site investigation), the order in

which the techniques are implemented, the size and

location of the survey grid applied, and the compatibility of

the techniques with the site (that is, compatible with

geology and physical access).

• An experienced geophysicist contractor who is skilled in

multiple geophysical methods and knowledgeable about

the physical and historic context of the survey and the

nature of the expected results.

Possible limitations of geophysical surveys include the

following:

• Geophysical surveys are equipment-intensive and may be

expensive to conduct.

• Geophysical survey equipment cannot distinguish between

cultural and geologic anomalies.

• Geophysical survey techniques are limited to near-surface

detection. There are limits to the depth and scale of

resolution.

• Geophysical survey equipment may not detect subtle

contrasts or weak signals. If the contrast between the

sought-after archeological material and incubating soil is

small, detection is hindered.

• Erroneous readings may occur as a result of distortion

from nearby cultural entities with physical or electromagnetic properties, such as subterranean utilities, powerlines,

metal fences, transmission towers, buildings, roads,

railroads, aircraft, and two-way radios.

include magnetic surveying with a magnetometer

and gravity surveying using a gravitometer. A

magnetometer measures the earth’s total magnetic field. It is useful for detecting buried ferrous

objects or magnetic anomalies in soils. A

gravitometer measures the anomalous acceleration of gravity due to mass/density relationships of

buried features. Currently, the technique has

limited use because detection is very subtle.
G E O G R A P H I C A L S U R V E Y T E C H N I Q U E S 3

Magnetometry

Magnetometry is used within a large landscape

area to detect the presence and location of

archeological resources with magnetic properties.

It is useful for a preliminary level of a subsurface

investigation and is particularly suitable for detecting brick structures and metallic artifacts.

Magnetometry, or magnetic surveying, uses the

proton magnetometer to measure the magnetic

susceptibility of buried materials. The earth’s total

geomagnetic field can be measured and used as a

control point of reference to compare local

magnetic interferences. When compared to the

total geomagnetic field, local disturbances or

anomalies can indicate the position of ferrous

objects, displaced soils, and earthen structures.

The magnetometer is a highly sensitive instrument, capable of measuring perturbations or

anomalies with an accuracy of one part in

100,000. The proton magnetometer is one of the

simpler, less expensive, and more accurate

geophysical instruments, and consequently is used

frequently for geophysical surveys. Acquisition of

spatial data over large areas is relatively easy, and

qualitative interpretations can be made rapidly

with relatively less geophysical experience. (See

Figure 4.)

Active Geophysical Survey Techniques

Active geophysical survey techniques involve

transmitting electrical currents, electromagnetic,

or acoustic energies into the earth’s surface.

Figure 1. This photograph of Virginius Island shows the proximity of the former industrial community to the Shenandoah River. The

nineteenth century buildings were largely destroyed by successive floods by the turn of the century. A geophysical survey of selected

areas of the island yielded information about the location of ruined residences and outbuildings. This information was used in

developing a treatment plan for the cultural landscape. Harpers Ferry National Historical Park. (NPS, 1865)
4 L A N D S C A P E L I N E S

Figure 2. Proposed treatment plan for the cultural landscape of Virginius Island. Data from geological surveys, archeological site

investigations, and historical research contributed to the development of this plan. Harpers Ferry National Historical Park. (NPS, 1992)

Figure 3. Proposed management zones for Virginius Island. The management zones are based upon historic land uses on the island,

which were identified through historical research and archeological site investigation. Harpers Ferry National Historical Park. (NPS,

1992)
G E O G R A P H I C A L S U R V E Y T E C H N I Q U E S 5

Active techniques include ground penetrating

radar, electrical resistivity, and electromagnetic

conductivity. Earthen material, such as soil or

rock, are generally considered to be relatively

poor conductors of energy. Much of the

energy that geophysical equipment introduces

is dissipated into the subsurface. Often geophysical receivers magnify the return signal to

compensate for the poor conduction of energy. A comparison of amplitude, frequency,

wavelength, and time delay between the input

and return signals leads to the detection of

buried cultural resources.

Ground Penetrating Radar

Ground penetrating radar (GPR) is used to

determine the depth and physical properties of

buried cultural and geologic features. It can

effectively map soil layers, depth to bedrock,

cavities, buried stream channels, burial sites,

underground utilities, structures (including concrete structures), and metallic objects.

GPR is most often used to measure reflected

low frequency electromagnetic energy, which is

introduced into the subsurface via a surfacecontact, transmitting antenna. (See Figure 5.) As

the energy passes through the earth, it may

encounter buried materials of varying electrical

properties. At these electrical interfaces, energy

may be either reflected or attenuated. A receiving antenna on the earth’s surface detects

reflected energy. The receiving antenna is

positioned in close proximity to the transmitting

antenna. Comparison of the return signal time

delay with the input signal (in billionths of a

second) is a function of the speed of the signal as

it passes through the buried material. This

comparison can be used indirectly to calculate

the depth of the buried material. A comparison

of the amplitude and frequency of the reflected

signal with the input signal provides information

about the physical properties of the buried

material.

Site-specific conditions may limit the success of

GPR in geophysical surveys. The presence of

highly conductive clay soils in proportions of 10

percent or more is probably the greatest limiting

factor affecting radar signals. Highly conductive soil

conditions result in the attenuation of electromagnetic energy, a reduction in signal velocity, and a

decrease in depth of signal penetration. Watersaturated soils also produce a highly conductive

environment. Seasonal groundwater level variations may be relevant in timing a ground penetrating radar survey.

Figure 4. A magnetic survey using a GEM 19 magnetometer.

Fort Laramie National Historic Site. (NPS, 1993)
6 L A N D S C A P E L I N E S

Electrical Resistivity

Electrical resistivity uses electrical resistance

(poor conductivity) properties to identify buried

cultural resources. A highly refined electrical

resistivity survey may be the most revealing

geophysical technique, but it is expensive to

perform because it requires a high number of

readings per unit area.

Resistivity experts interpret electrical resistivity

patterns to identify the presence of nearly all

forms of constructed features, such as foundations, paths, and roads. The technique can also

reveal compacted soils, indicative of a former

pathway, and disturbed soils, such as those found

at burial sites and cultivated fields. Electrical

resistivity is useful for measuring depth to bedrock

and is often performed before GPR in geophysical surveys involving multiple techniques. Depth

to bedrock measurements are useful in calibrating

GPR equipment.

Electrical resistivity uses current electrodes to

introduce into the soil an electrical current of

known amplitude (amps) and frequency (volts),

and potential electrodes with an ohmmeter to

measure resistance changes in the soil, vertically

and horizontally. (See Figure 6.) Measurements of

vertical changes in resistivity are called “soundings” and measurements of horizontal changes in

resistivity are called “profiling.” The technique

requires at least three individuals to move two

current electrodes and two potential electrodes

along a survey grid. It is assumed that the incubating soil has a homogeneous resistivity (due to an

assumed even distribution of soil and water) and

that buried cultural resources can be identified as

anomalous readings of resistance.

Along survey gridlines, changes in resistance

readings are used to create “contour maps” of soil

resistivity. On the map, concentric contours

emanating from a location (called a “spot elevation”) represent material of lowest conductivity,

Figure 5. A ground penetrating radar being pulled across the

ground. Lockwood Stage Stop, Pinon Canon Maneuver Site,

Colorado. (NPS, 1991)

Figure 6. An electrical resistivity survey using a Gossen resistivity

meter. Scott Air Force Base. (NPS, n.d.)
G E O G R A P H I C A L S U R V E Y T E C H N I Q U E S 7

or conversely, greatest resistance. Because soil

conductivity is directly related to the presence of

water, locations measuring the greatest resistance

will have a lower soil-water content. Nonsaturated soil conditions reveal more contrasts

between potentially buried cultural resources

(that have lower water content) and native soil

material (having higher water content).

Ideally, electrical resistivity tests should be

performed in more than one season with

varying soil-water conditions. In some geologic

conditions the native soil may have a lower

water content and therefore higher resistivity

than buried cultural resources. Because resistivity is directly related to permeability, degree of

saturation, and the chemical nature of entrapped

fluids, prior knowledge of indigenous geologic

conditions is requisite to accurately interpret

resistivity data.

Electromagnetic Conductivity

Electromagnetic conductivity, also called EM and

induction, is used to detect and differentiate

metallic artifacts buried near the earth’s surface.

The technique locates near-surface cultural

features (structures, compaction, excavation, and

habitation sites) by their various water saturations

(their conductivity). A conductivity measurement

is the reciprocal of resistivity, so in theory the

results of a lateral conductivity survey should

mirror the results of a resistivity profile.

The main advantage to using conductivity over

resistivity is that the measuring instrument does

not require surface contact. Two individuals are

required to perform the technique, but the

conductivity instrument can be moved from

station to station by one operator. Resistivity

requires a crew of at least three to move and

place electrodes in the ground along a survey line.

(See Figure 7.)

Electromagnetic conductivity uses a nonsurface

contacting radio transmitter and receiver. The

transmitter induces an electromagnetic field in

the earth, causing an electrical current to flow.

The electrical current generates a secondary

magnetic field that causes the flow of an electrical current signal in the receiver. The receiver

signal is measured for conductivity by a voltmeter incorporated in the EM instrument. The

voltmeter is calibrated to measure the soil as

having a homogeneous level of conductivity. It is

assumed that buried cultural resources cause

anomalies in the homogenous level of conductivity detected along survey lines. Large fluctuations in conductivity are indications of highly

conductive subsurface materials, such as buried

Figure 7. An electromagnetic conductivity survey using a Geonics

EM38 soil conductivity meter. Fort Laramie National Historic

Site. (NPS, 1993)
8 L A N D S C A P E L I N E S

utilities. Observing the physical extent and orientation of the anomaly can provide clues to its

identification.

SOURCES OF GEOPHYSICAL

PROSPECTING EQUIPMENT

AND SURVEYORS

United States Governmental Agencies

United States Geological Survey

United States Bureau of Reclamation

United States Bureau of Mines

Environmental Protection Agency

State Agencies

Geologic Surveys

Health & Environmental Agencies

Universities and Colleges

Geological Departments

Geophysical Departments

Engineering Departments

Private and Nonprofit Organizations

Private Concerned Citizens

Geophysical Equipment Manufacturers

Geophysical Equipment Rental Companies

Geophysical Consultants

For access to the last five groups, acquire a

copy of the Geophysical Directory, published

each March. This directory provides the most

comprehensive listing of sources of equipment

and geophysical survey experts available.

The Geophysical Directory

2200 Welch Avenue

P.O. Box 130508

Houston, TX 77219

Phone 713-529-8789

Fax 713-529-3646

REFERENCES

Contracting Archeological

Services Reference

Jameson, J.H. Jr. et al. 1990. Federal Archeological Contracting: Utilizing the Competitive Procurement Process. Technical Brief, no. 7, ISSN

1057-1574. Georgia: USDI, NPS, Interagency

Resources Archeological Services Division,

Southeast Regional Office.

General References

Lyons, T.R., and J.L. Elbert, eds. 1977. Remote

Sensing: A Handbook for Archeologists and Cultural

Resource Managers. Washington, DC: USDI, NPS,

Cultural Resources Management Division.

Lyons, T.R., R.K. Hitchcock, and W.H. Wills.

1978. Remote Sensing: Aerial Anthropological

Perspectives: A Bibliography of Remote Sensing

in Cultural Resource Studies, Supplement No.3.

Supplement to “Remote Sensing: A Handbook

for Archeologists and Cultural Resource Managers.” Washington, DC: USDI, NPS, Cultural

Resources Management Division.
G E O G R A P H I C A L S U R V E Y T E C H N I Q U E S 9

Morain, S. A., and T.K. Budge. Remote Sensing:

Instrumentation for Non-destructive Exploration

of Cultural Resources, Supplement No.2. Supplement to “Remote Sensing: A Handbook for

Archeologists and Cultural Resource Managers.”

Washington, DC: USDI, NPS, Cultural Resources

Management Division.

Wood, W.R., R.K. Nickel, and D.E. Griffin.

1984. Remote Sensing: The American Great

Plains, Supplement No.9. Supplement to “Remote Sensing: A Handbook for Archeologists

and Cultural Resource Managers.” Washington,

DC: USDI, NPS, Cultural Resources Management Division.

Magnetometry References

Barrows, L., and J.E. Rocchio. Summer 1990.

Magnetic Surveying for Buried Metallic Objects.

Ground Water Monitoring Review: 204-209.

Bennet, C.B., and J.W. Weymouth. 1982.

Magnetic Reconnaissance Program in the

Dolores Archeological Project: Interpretation of

Data Collected During the Field Season 1980.

Colorado: University of Colorado Dolores

Archeological Program.

Burns, P.K. 1981. Magnetic Reconnaissance in

the Dolores Archeological Program. Master’s

thesis. Nebraska: University of Nebraska,

Lincoln, Department of Anthropology.

Burns, P.K., R. Huggins, and J.W. Weymouth.

1983. Study of Correlation Between Magnetic

Reconnaissance and Excavation in the Dolores

Program. Dolores Archeological Program

Technical Reports, Report No. DAP-078. Utah:

USDI, Bureau of Reclamation, Salt Lake City.

Heimmer, D.H. 1992. Near Surface, High

Resolution Geophysical Methods for Cultural

Resource Management and Archeological

Investigations. Denver: USDI, NPS, Rocky

Mountain Regional Office, Interagency Archeological Services.

Huggins, R. 1981. Magnetic Reconnaissance

Program in the Dolores Archeological Program:

Interpretation of Data Collected During Field

Years 1981 and 1982. Colorado: University of

Colorado Dolores Archeological Program.

________. 1983. Magnetometer Results.

Dolores Archeological Program: Field Investigations and Analysis—1978. 193-251. Edited by

D. A. Bretevnitz. Denver: USDI, Bureau of

Reclamation.

Kaczor, J., and J. Weymouth. 1981. Magnetic

Prospecting: Preliminary Results of the 1980

Field Season at the Toltec Site, 3LN42. Southeastern Archeological Conference Bulletin 24:

118-123.

Mason, R.J. 1984. An Unorthodox Magnetic

Survey of a Large Forested Historic Site. Historical Archeology 18(2): 54-63.

Tabbagh, A. 1984. On the Comparison Between

Magnetic and Electromagnetic Prospection

Methods for Magnetic Features Detection.

Archaeometry 26(2): 171-182.
10 L A N D S C A P E L I N E S

Von Frese, R.R.B. 1984. Archeomagnetic Anomalies at Midcontinental North American Archeological Sites. Historical Archeology 18(2): 4-19.

Von Frese, R.R.B., and V.E. Noble. 1984. Magnetometry for Archeological Exploration of Historical

Sites. Historical Archeology 18(2): 38-53.

Von Frese, R.R.B., and B. Bevan. 1983. Combined Magnetic and Ground Penetrating Radar

Survey of an Archeological Site in Oklahoma.

International Geoscience and Remote Sensing

Symposium. San Francisco, digest, vol. I, section

WP.3. New York: IEEE.

Ground Penetrating Radar References

Amato, L., and G. Di Maio. 1990. Ground

Penetrating Radar for the Identification of the

Volcanoclastic Sequence of AD 79 Vesuvian

Eruption—Pompeii—Southern Italy. Third

International Conference on Ground Penetrating

Radar, Lakewood, Colorado.

Annan, A.P., J.L. Davis, and D. Gendzwill. 1988.

Radar Sounding in Potash Mines, Saskatchewan,

Canada. Geophysics 53(12): 1556-1564.

Bevan, B., D.G. Orr, and B.S. Blades. 1984.

The Discovery of the Taylor House at the

Petersburg National Battlefield. Historical Archeology 18(2): 64-74.

________. 1979. A Ground Penetrating Radar

Survey at the Deer Creek Site. Report prepared

for the US Army Corps of Engineers, Tulsa

District, Tulsa, Oklahoma.

________. 1980. A Second Season at Deer

Creek: Radar and Electromagnetic Surveys.

Report prepared for the US Army Corps of

Engineers, Tulsa District, Tulsa, Oklahoma.

________. 1991. The Search For Graves.

Geophysics 56: 1310-1319.

Bevan, B., and J. Kenyon. 1975. Ground Penetrating Radar for Historical Archeology. MASCA

Newsletter 11(2): 2-7.

Butler, Dwain K., ed. March 1992. Miscellaneous

paper GL-92-40. In Proceedings of the Government Users Workshop on Ground Penetrating

Radar Applications and Equipment. Vicksburg,

Mississippi: Department of the Army, Waterways

Experiment Station, COE.

Daniels, J. March 1988. Locating Caves, Tunnels

and Mines. Geophysics: The Leading Edge of

Exploration.

________. 1988. Fundamentals of Ground

Penetrating Radar. Symposium on the Application of Geophysics to Engineering and Environmental Problems. Golden, Colorado.

Davis, J.L., and A.P. Annan. 1989. Ground

Penetrating Radar for High-Resolution Mapping

of Soil and Rock Stratigraphy. Geophysical

Prospecting 37: 531-551.

De Vore, S.L. 1990. Ground Penetrating Radar as

a Tool in Archeological Investigations: An Example

from the Fort Laramie National Historic Site. The

Wyoming Archeologist 33(1-2): 23-38.
G E O G R A P H I C A L S U R V E Y T E C H N I Q U E S 11

Fischer, P.M., S.G.W. Follin, and P. Ulriksen.

1992. Surface Interface Radar Survey at Hala

Sultan Tekke, Cyprus. Studies in Mediterranean

Archeology 57: 495-508.

Geophysical Survey Systems, Inc. 1989. Radan

Instruction Manual. MN43-101 Release 3.0.

________. 1991. Surface Interface Radar 10

Manual. New Hampshire, New Salem.

Heimmer, D.H. 1992. Near Surface, High

Resolution Geophysical Methods for Cultural

Resource Management and Archeological

Investigations. Denver: USDI, NPS, Rocky

Mountain Regional Office, Interagency Archeological Services.

Heimmer, D.H., G.C. Davenport, J. Lindemann,

and J. Gilmore. 1989. Geophysics for Archeological Assessment: Ft. William Discovered? Fort

Laramie National Historic Site, Wyoming. Symposium on the Application of Geophysics to

Engineering and Environmental Problems.

Golden, Colorado.

Mellett, J., and J. Geismar. 1990. GPR Survey of

an African-American Cemetery in Little Ferry,

New Jersey. Third International Conference on

Ground Penetrating Radar. Lakewood, Colorado.

Sheets, P.D., W.M. Loker, H.A.W. Spetzler,

R.H. Ware, and G.R. Olhoeft. 1985. Geophysical Exploration for Ancient Maya Housing at

Ceten, El Salvador. National Geographic Society

Research Reports.

Ulricksen, C.P. 1983. Application of Impulse

Radar to Civil Engineering. Hudson, New

Hampshire: Geophysical Survey Systems.

Vickers, R.S., and L.T. Dolphin. 1975. A Communication on an Archeological Radar Experiment at Chaco Canyon, New Mexico. MASCA

Newsletter 11(1): 6-8.

Electrical Resistivity References

Atkinson, R.F.C. 1963. Resistivity Surveying in

Archeology. The Scientist and Archeology. 1-30.

Edited by E. Pyddoke. London: Phoenix House.

Bevan, B. 1991. A Resistivity Survey at the

Lockwood Stage Station. Denver: USDI, NPS.

Carr, C. 1977. A New Role and Analytical Design

for the Use of Resistivity Surveying in Archeology.

Midcontinental Journal of Archeology 2: 161-193.

________. 1982. Handbook on Soil Resistivity:

Interpretation of Data from Earthen Archeological Sites. Illinois: Evanston, Center for American

Archeology Press.

Ellwood, B.B. 1990. Electrical Resistivity Surveys

in Two Historical Cemeteries in Northeast

Texas: A method for delineating unidentified

burial shafts. Historical Archeology 24: 91-98.

Ford, R.I., and R.O. Keslin. 1969. A Resistivity

Survey at the Norton mound Group, 20KT1,

Kent County, Michigan. The Michigan Archeologist 15(3): 86-92.
12 L A N D S C A P E L I N E S

Goodyear, Frank H. 1971. Archeological Site

Science. Chapter 8, “Wood and Charcoal.” New

York: American Elsevier Publishing.

Heimmer, D.H. 1992. Near Surface, High

Resolution Geophysical Methods for Cultural

Resource Management and Archeological

Investigations. Denver: USDI, NPS, Rocky

Mountain Regional Office, Interagency Archeological Services.

Hranicky, W.J. 1972. Application of Resistivity

Surveying to American Archeology. The

Chesopiean 10: 43-50.

Huggins, R., and J.W. Weymouth. 1981. A

Probe Resistivity Survey and Analysis at the

Deer Creek Site (34KA3), Oklahoma. Report

submitted to the US Army Corps of Engineers,

Tulsa District, Oklahoma.

Electromagnetic Conductivity

References

Bevan, B. 1983. Electromagnetics for Mapping

Buried Earth Features. Journal of Field Archeology 10(1): 47-54.

Heimmer, D.H. 1992. Near Surface, High

Resolution Geophysical Methods for Cultural

Resource Management and Archeological

Investigations. Denver: USDI, NPS, Rocky

Mountain Regional Office, Interagency Archeological Services.

Howell, M. 1966. A Soil Conductivity Meter.

Archaeometry 9: 20-23.

McNeill, J.D. 1980. Electromagnetic Terrain

Conductivity Measurement at Low Induction

Numbers. Ontario, Canada: Geonics Limited.

________. 1985. Operating Manual for EM31-d

Non-Contacting Terrain Conductivity Meter.

Canada: Mississauga, Geonics Limited.

Musson, C.R. 1968. A Geophysical Survey at

South Cadbury Castle, Somerset. Using the

Howell Soil Conductivity Anomaly Detector

(SCM). Prospezioi Archeologiche 3: 115-121.

Parchas, C., and A. Tabbagh. 1979. Simultaneous Measurements of Electrical Conductivity

Prospecting. Archaeo-Physika 10: 682-691.

Tabbagh, A. 1986. Applications and Advantages

of the Slingram Electromagnetic Method for

Archeological Prospecting. Geophysics 51: 576-

584.

Tite, M.S., and C. Mullins. 1970. Electromagnetic

Prospecting on Archeological Sites Using a Soil

Conductivity Meter. Archeometry 12(1): 97-104.

The mission of the Department of the Interior is to protect

and provide access to our Nation’s natural and cultural

heritage and honor our trust responsibilities to tribes.

U.S. Department of the Interior

National Park Service

Cultural Resources

Park Historic Structures & Cultural Landscapes