The Schlumberger array is used to determine near surface resistivities of various lithologies within the Boonah area, southeast Queensland. The project aims to distinguish factors having significant effect on weathering layer parameters. Previous investigations around the world show that any underlying rock has a unique effect on the resistivity of the overlying soil profile and weathered layer. However, little work has been done in areas with a subhumid-subtemperate climate.
Results from the Boonah area support findings from previous investigations. The resistivity of the weathered layer is found to increase with the increase in silica content of the parent rock, increase of resistance to weathering of the parent rock, and increased depth to the water table. In addition, electrical properties of the weathered layer are found to be intrinsically related to the weathering regime, which in turn is dependent on topography and climate.
In terrains with little or no fresh rock outcrop resistivity techniques could prove very useful in mapping the underlying geology and investigating groundwater accumulations.