Using GPR for micro-analyses of soils and karst features on the Chiefland Limestone Plain in Florida

Abstract

Karst and sand/limestone and sand/clay/limestone interfaces were investigated in two study plots on the Chiefland Limestone Plain in west-central Florida. The Chiefland Limestone Plain has many recently formed sinkholes and solution pipes that mark the landscape. Paleokarst features, such as relict sinkholes and solution pipes (with soils burying them), are not obvious due to the lack of surface expression. Prior to the development and use of ground-penetrating radar (GPR), accurate location of the paleokarst features, as well as determination of their configuration, was nearly impossible. Knowledge of the location of these features is important because the presence of these features indicates areas of subsurface instability. Additionally, in order to optimize the capability of GPR on karst, documentation of the effects of selected soil properties on the radar output, and the examination of the relationships of the clay layer, bedrock, and surface topography are imperative. The objectives of this study were: (1) to analyze selected soil properties and compare these properties to GPR performance in resoluting the sand/limestone (C/R horizons) and sand/clay/limestone (E/Bt/R horizons) interfaces; (2) to use GPR graphic data to identify paleo-sinkholes and solution pipes using computer-simulated diagrams of the limestone interface; and (3) to discuss implications for the association between the clay layer, bedrock, and surface topography in two study plots on the Chiefland Limestone Plain.