Case Study
3030 Winchester
Archaeo-Physics LLC was contracted by GCM Services,
Inc. to perform geophysical survey as part of archaeological investigations
at the 30-30 Winchester Site (48CA3030), a prehistoric campsite
in Campbell County, Wyoming. Magnetic field gradient survey was
successful in detecting several anomalies that were thought to be
caused by prehistoric hearths (later verified by excavation). In
general, the site had very little magnetic "clutter" due
to modern metal or geologic variance. The standard deviation of
magnetic data after processing was 0.4nT. Anomalies thought to be
caused by hearths have amplitudes up to several nanoTeslas and contrast
starkly with the very uniform background.
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A cluster of several roughly circular magnetic highs
appear in the southeastern part of the survey area, which is adjacent
to the bank of the nearby creek. These anomalies were though to
be caused by hearths associated with the prehistoric occupation
of the site. This was later confirmed by excavation.
The high-amplitude bipolar anomaly near the center
of the magnetic map was excavated as well, but no apparent source
was dicovered. Laboratory testing of soil samples and the geometry
of the anomaly has shown it to be an example of lightning-induced
remanent magnetization (Verrier et al.).
Related content:
Geophysical survey
as an approach to the ephemeral campsite problem
Lightning-induced anomalies on archaeological
sites
