Perkiomen Geophysics Results

Laura Sherrod - 2016

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.

Magnetic results of one of the surveys in September 2016


GPR results showing the concave reflector from the January 2016 survey

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. 


David Vales operates the magnetometer in January 2016 Kurtis Brown operates the GPR in September 2016 David Maguire operates the GPR as Ricky McDermott takes notes in September 2016  

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