Application of Magnetic and Geotechnical Methods for Archaeological Site Investigations

Abstract : The overall objective of this research was to develop and use methods to measure and assess vehicle impacts on buried archaeological deposits. The need for this stems from the large number of archeological resources located on U.S. Department of Defense (DOD) sites where training includes vehicular activities. Specifically, the objectives of this research were to verify the quantitative relationship between soil compaction and changes in magnetic susceptibility, to develop a geotechnical model of subsurface compaction under a vehicle rut, to evaluate various compaction and deformation measurement methods in a controlled setting, to apply these measurements at the field scale, and to use magnetic modeling to interpret results. Multiple experiments were conducted, with each experiment building on the results of the previous ones. The first experiment was a core compaction test that verified the relationship between bulk density and magnetic susceptibility. Then a geotechnical model was developed, which provided a tool for estimating the compaction profile under a rut based on stress curves under footings with static loading. The accuracy and shortcomings of the geotechnical model were demonstrated in later tests. The first series of tests provided a detailed investigation of compaction of uniform soil within a large wooden box. These experiments were used to refine the measurement techniques, to verify the geotechnical model, and to develop a better understanding of the depth and distance that a surface impact could propagate into the subsurface. Overall, the results of the experiments demonstrated that cone penetrometer and down-hole volumetric magnetic susceptibility measurements could be used to accurately determine the magnitude of compaction, and that the geotechnical model accurately predicted compaction in the homogeneous soil.

[1]  C. Frederick,et al.  Proton magnetometer investigations of burned rock middens in west-central Texas: Clues to formation processes , 1990 .

[2]  Braja M. Das,et al.  Introduction to Geotechnical Engineering , 1985 .

[3]  Robert F. Butler,et al.  Paleomagnetism: Magnetic Domains to Geologic Terranes , 1991 .

[4]  Lewis E. Somers,et al.  Geophysical Surveys in Archaeology: Guidance for Surveyors and Sponsors , 2003 .

[5]  John A. Dearing,et al.  Frequency-dependent susceptibility measurements of environmental materials , 1996 .

[6]  Pierre-Etienne Mathé,et al.  Soil anomaly mapping using a caesium magnetometer: Limits in the low magnetic amplitude case , 2006 .

[7]  Inversion of anomalies due to remanent magnetisation: an example from the Black Hill Norite of South Australia , 2011 .

[8]  T. Yonetani,et al.  Magnetic susceptibility. , 1972, Methods in enzymology.

[9]  Subir K. Banerjee The regional and temporal significance of primary aeolian magnetic fabrics preserved in Alaskan loess , 2004 .

[10]  Lisa Tauxe,et al.  Paleomagnetic principles and practice , 1998 .

[11]  J. Schön,et al.  The influence of soil moisture on magnetic susceptibility measurements , 2006 .

[12]  François Lévêque,et al.  High resolution magnetic survey for soil monitoring: detection of drainage and soil tillage effects , 2003 .

[13]  P. Parkes Current scientific techniques in archaeology , 1988 .

[14]  L. Tauxe,et al.  Relative paleointensity in sediments: A Pseudo‐Thellier Approach , 1995 .

[15]  B. Marwick Element Concentrations and Magnetic Susceptibility of Anthrosols: Indicators of Prehistoric Human Occupation in the inland Pilbara, Western Australia , 2005 .

[16]  L. Tauxe,et al.  Depositional remanent magnetization: Toward an improved theoretical and experimental foundation , 2006 .