North American Database of Archaeological Geophysics
North American Database of Archaeological Geophysics
Abstract/Summary:
Project Name: Monticello, VA;
Reference: Heath, B.J. and M. Strutt. (1991). Applications for Remote Sensing: Testing a Cemetery at Monticello. The Thomas Jefferson Memorial Foundation and The Corporation for Thomas Jefferson's Poplar Forest. Presented at the 1991 Society for Historical Archaeology Meeting, Richmond, Virginia.
During the fall of 1990 the authors, assisted by Dr. Bill Hanna of the US Geological Survey and staff archaeologists at Monticello, combined the techniques of gradiometer survey, surface mapping, and core sampling in an effort to confirm the existence of a burial ground on the Monticello property. Oral tradition identifies the area, located in the center of what is today the major visitor parking lot for the museum, as a slave graveyard dating to Jefferson's lifetime. By combining a series of non-intrusive or minimally intrusive methods of investigation, this study attempted to both define the pattern and extent of disturbances, and to further test and refine the use of remote sensing as a viable method for locating shallow, small features such as historic period graves.
Surface mapping and coring tend to support oral accounts that the survey area served as a burial ground in the past. The size and positioning of the depressions, both in north-south rows, and perhaps more significantly, in east-west alignment, strongly suggests that they are cultural rather than natural phenomena, matching Western burial customs. The positioning of stones at the "head" and "foot" of one depression, and at the eastern end of another, follows the historic practice of marking graves with field stones. While core samples could neither confirm nor deny function, they did indicate that at least 25% of the features were characterized by deep disturbances, and 100% of the depressions tested were filled with disturbed subsoil. An overlay of the map of depressions, stones, a utility line and trees with the gradient map reveals some possible correlation between the depressions and subsurface magnetic anomalies. While it is not possible to match depressions to anomalies exactly, the gradiometric data clearly shows areas of disturbance that match those areas mapped as graves.
Non-intrusive or minimally intrusive investigations revealed twenty-four features in an area measuring roughly 60'x70'. Although we are unable to date these features, we now have strong evidence that they are indeed graves. We have also demonstrated the strengths and limitations of gradiometer survey for locating graves in a fairly disturbed, highly magnetic area. We have found that while straight magnetometer surveys in areas of high surface magnetic disturbance do not yield useful data, gradiometer surveys do. Utility lines, traffic, and magnetic soils contributed to, but did not negate, the validity of the survey. Further refinements of grid interval and sensor height may make the gradiometer a more efficient tool for remote sensing in graveyards.