INTEGRATED GEOPHYSICAL STUDIES OF A LATE 18TH CENTURY AFRICAN-AMERICAN HOMESTEAD IN ACADIA NATIONAL PARK, MAINE

In order to establish the extent of the 18th century Thomas Frazier homestead and locate structures of a 19th century settlement the area was subjected to a geophysical survey employing ground penetrating radar (400 mHz antenna), 24 probe electrical resistivity system (pole-dipole array), and dual frequency (14kHz, 9kHz) electromagnetic induction surveys. Thomas Frazier, freedman, was, perhaps, the first African-American to settle in downeast Maine. His presence is recorded as early as 1776. The remains of his homestead, on the Schoodic Peninsula at Acadia NP, consists of a shallow cellar hole and a scatter of period artifacts located adjacent to a recently constructed rest room and paved parking area. The site was also the location of a small 19th century settlement abandoned and torn down during the early 20th century. The site, although small, contains three distinct surfaces. Paved parking areas were surveyed with the GPR and EM. Heavily vegetated/wetland areas were accessible only to the resistivity equipment. Grassy areas were surveyed with all equipment. In addition, a seismic refraction survey was conducted to determine depth to bedrock. The survey grid was established and detailed elevation data collected which allowed topographic correction of the geophysical data as well as preparation of a site map with a 10cm contour interval. Grid density varied from .5 to 1 meter. Site geology consists of 1 – 3 meters of silty sand overlying glacially smoothed granites of the Mt. Desert intrusive complex. All surveys were calibrated using the existing cellar hole as a reference. Site conditions for all three methods were good with GPR providing the most detailed data. The most useful EM frequency proved to be 9kHz in vertical dipole orientation with good resolution of structures although all methods detected the same additional structures. Two additional structures were located as well as several anomalous features which lacked the regularity of a building foundation footprint. The survey demonstrated the need for redundant systems to survey a site with varied surface and subsurface conditions.