North American Database of Archaeological Geophysics
North American Database of Archaeological Geophysics
Abstract/Summary:
Project Name: Petaluma Adobe State Historic Park (CA-Son-2294/H), CA;
Reference: Silliman, S.W., Farnsworth, P., and K.G. Lightfoot (2000). Magnetometer Prospecting in Historical Archaeology: Evaluating Survey Options at a 19th-Century Rancho Site in California. Historical Archaeology 34(2):89-109. (used with permission).
Silliman, S.W. (2000). Colonial Worlds, Indigenous Practices: The Archaeology of Labor on a 19th-Century California Rancho. Ph.D. Disseration, University of California-Berkeley.
Geophysical surveys were conducted at Petaluma Adobe State Historic Park in northern California in June of 1996 and September of 1997. The main objective of the study was to compare magnetic results obtained using various instruments and methods of collection. The variables that were examined included instrument type (alkali-vapor versus proton precession), types of sensors (total field versus vertical gradient), sensor height, sampling interval, and basestation correction procedures. The results of the comparisons were used to determine the best methods for magnetic data collection with regard to such factors as survey speed, labor, and cost. Based on these criteria, it was determined that the alkali-vapor gradiometer is the best suited for historical archaeological research. Likewise, the importance of such variables as sensor height, gradiometer configuration, and basestation correction in obtaining high-quality magnetic data was demonstrated.