Case Study
Mission San Antonio de Padua
Monterey County, California
San Antonio de Padua is a historic mission located
in Monterey County, California. The investigation conducted by Archaeo-Physics
consisted of electrical resistance, ground penetrating radar (GPR),
and magnetic field gradient surveys over over portions of the archaeological
remains of a large adobe communal housing structure that was originally
built to provide housing for married Salinan neophytes.
The primary objective of this geophysical investigation was to provide
baseline data using established geophysical methods for comparison
with two relatively new geophysical survey methods, thermal imaging
and diving wave seismic refraction tomography, being assesed by
MSE Technology Applications, Inc. A secondary objective of the investigation
was to provide geophysical imagery in support of ongoing archaeological
investigations being conducted at the site by Dr. Robert Hoover,
of California Polytechnic State University.
The investigation was successful in identifying a number
of geophysical anomalies that appear to represent historic archaeological
features. Each of the three methods applied during this investigation
are sensitive to contrasts in different material properties, as
might be expected, the resulting images vary somewhat in resolution
and detail.
Electrical resistance and GPR survey methods were quite successful
in mapping the main structure stone foundations, interior adobe
room blocks, possible tiled room floors, and previously unknown
adjacent structures to the grid north of the main structure. Additionally,
the deeper GPR time slices have detected linear anomalies oriented
about 45 degrees from the main structure that may represent earlier
archaeological features. Magnetic field gradient survey successfully
detected portions of the main structure, although signal clutter
from numerous high amplitude thermoremanent fields prevents detailed
interpretation of the magnetic images.
