Some geologic materials that may have a relatively higher resistivity include, for example: air-filled voids, sands and gravels, and bedrock. In general, relatively low resistivity areas (high conductivity) are represented as shades of blue, intermediate resistivity areas are represented by yellow and green, and relatively high resistivity areas (low conductivity) are represented as shades of orange and red.
The resistivity of a material is simply the inverse of the conductivity.
The change in voltage measured by the potential electrodes allows for the resistivity of the subsurface materials to be calculated. The electrical resistivity method consists of the injection of electrical current into the subsurface by current electrodes, and measurement of the change in voltage by potential electrodes. This study is of interest to the Carroll Cave Conservancy (CCC) and the Carroll Cave Survey (CCS) because if this geophysical technique was found to be useful, it may be utilized by the CCS in the future for surficial exploration of unknown cave passages. The purpose of this reconnaissance study was to determine the applicability of the electrical resistivity geophysical method in surficial exploration for subsurface voids. University of reconnaissance electrical resistivity survey was conducted over portions of known cave passage of Carroll Cave in Camden County, Missouri, in late summer 2003. (unpublished report submitted to the Carroll Cave Conservancy)
A Reconnaissance Electrical Resistivity Survey Over Carroll Cave,
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