Geophysical investigations
were performed to provide subsurface images
using a
400MHz GSSI SIR 3000 GPR system and a Geometrics
G-858 magnetometer in
gradiometer mode. Lines
were spaced at 1.5ft to provide complete
coverage of the survey area.
Several
magnetic anomalies were observed in the
survey blocks.
Some of these were attributed to
surface features (well head) or known
subsurface features (cistern), but others of
these features need additional investigation
to determine the source.
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Magnetic
results of one of the surveys in September
2016
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GPR results showing the concave reflector
from the January 2016 survey
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Foundation
stones should appear as hyperbolic
reflections in the GPR profiles due to the
discrete nature of the stone in the soil and
the diffraction of the radar energy off the
edges of the stones.
Several
hyperbolic reflections were identified in
the analysis of the GPR profiles, but plots
of the locations of these reflections did
not correspond to the general shape of a
building.
Another category
of GPR anomaly was observed at this site: a
high amplitude, concave reflection.
This anomaly
occurred only in a single survey block and
the size of the anomalies may correspond to
the approximate size of buildings.
However,
conclusive interpretations are not possible
with the geophysical data collected,
particularly in this location where
anthropogenic disturbance of the soils have
occurred recently.
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