Archaeo-Physics, LLC - geophysical survey and subsurface mapping

Case Study

Odessa Yates Site

1998 Field Season Results

See also: Summary page - 2000 Field Season - 1999 Field Season - the University of Oklahoma Odessa Yates website

In 1998, Archaeo-Physics conducted a preliminary survey as part of an ongoing research project by the University of Oklahoma. Both resistivity and magnetic were collected on a portion of the site. Several apparent architectural features were identified from the geophysical data. The results were verified by conducting limited excavation and coring.

The green circles on the resistance map to the left represent high-resistance anomalies, interpreted as prehistoric architectural features.

Ground Truthing (sub-surface testing) was performed on the anomalies marked A and B. This testing confirmed the cultural origin of these features (see below).

The composite map to the left shows magnetic and elevation data overlaid as contours on the electrical resistance data image map. White lines represent elevation contours, while colored lined represent magnetic gradient contours (red+, yellow-, interval 2nT)

Ground truthing
Test excavation unit showing collapsed mud brick wall associated with resistance anomaly B.

Ground truthing
Testing geophysical anomalies with a truck mounted hydraulic coring rig.
Ground truthing
Soil core showing dark staining with charcoal and bison bone from an apparent living floor associated with resistance anomaly A.

Ground truthing

Testing of geophysical anomalies, or "ground truthing", was conducted on a sample of the geophysical anomalies at the Odessa-Yates Site using a combination of non-invasive and invasive techniques. The objective was to identify the source of the geophysical anomaly in the least invasive and least time consuming manner.

Ground truthing began with the creation of a 1:100 scale map with grid lines at one meter intervals in the North-South and East-West directions. This map was used to locate the precise position of each anomaly within our grid system.

Among the Anomalies selected for testing were the anomalies labeled as A and B on the resistance map (the map shows only a portion of the survey). Both were presumed to be architectural features. Anomaly A has associated magnetic anomalies and B does not.

Once the position of the anomaly was located on the ground, testing was conducted using the following three methods:

  • Ground penetrating radar survey
  • Systematic soil coring
    (3" diameter truck mounted hydraulic core)
  • One square meter test excavation units

Because of the high conductivity of the soil and limited dielectric contrast, the ground penetrating radar yielded inconclusive results.

Coring of anomaly A revealed level floor with a dark organic cultural deposit containing much charcoal and bone.

Coring of anomaly B was inconclusive, but excavation showed it to be a structure made of very friable mud brick, but without associated cultural material.

top home Case studies Methodology Survey inquiries Contact Search

Website ©Archaeo-Physics LLC. Unless otherwise noted, materials from this website may be reproduced for nonprofit educational purposes; please cite or link to source page. This page last updated February 9, 2012