Silver Bluff (38AK7)
18th Century Trading Post and Fort, South Carolina
Silver Bluff was the site of a trading post operated
by George Galphin for many years prior to the American Revolution.
It was occupied and fortified by the British (who renamed it Fort
Dreadnought) before being destroyed by American Forces in 1781.
Excavated portions of the site have revealed numerous wall trenches,
pits, postholes, and other archaeological features. Geophysical
survey results from unexcavated portions of the site show numerous
anomalies consistent with achaeological features that have been
found elsewhere on the site. Large scale patterning reveals much
of the layout of the site that would be unknown without extensive
excavation, which would be both costly and destructive.
Ground Penetrating Radar
Sandy soils with very high electrical resistance were ideal
for propagation of the radar signal. This data plot represents
the statistical variance of signal reflected from estimated
depths of 30-80cm. Although tree roots created significant
"clutter" in portions of the site, extensive rectilinear
patterning caused by architectural features is visible over
much of the survey area. Discrete "point" anomalies
may have a variety of sources, but many are consistent with
pit and postmold features found in previously excavated portions of the site.
Although fine detail associated with individual features is
not obviously visible in the resistance data, large scale
site patterning is readily apparent. Resistance anomalies
may be due to the distribution of organic components and disturbed
soils as well as architectural and other features. Although
many are faint, discrete resistance anomalies that correlate
with anomaies in the GPR dataset are likey to be of interest.
Magnetic Field Gradient
Magnetic survey results show a distribution of high-amplitude
(in the colored ranges of the scale) anomalies that is typical
of historic sites. Many of these anomalies are bipolar (having
both positive and negative components). This type of anomaly
is generally caused by historic or modern artifacts of metal
or brick. Excavators have found that a high percentage of
the metal recovered from the site was associated with the
18th century occupation. Substantial amounts of brick are
also present, and are thought to be associated with George
Galphin's residence. Comparison of magnetic survey results
with other datasets may identify metal and brick components
of features. Although the survey results are dominated by
this "scatter" of metal and brick, fainter rectilinear
anomalies and diffuse magnetic highs may represent architectural
and organically enriched features.
These surveys were performed by Archaeo-Physics as
part of "New
Approaches to the Use and Integration of Multi-Sensor Remote Sensing
for Historic Resource Identification and Evaluation"
a study sponsored by SERDP (Strategic Environmental Research and
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purposes; please cite or link to source page. This page last updated
February 9, 2012