Karst within the Confining unit of the Floridan Aquifer: A Geophysical Investigation

Occurrences of surficial karstic depressions in south-central Georgia are generally attributed to the dissolution within the Floridan aquifer even though it is overlain by a confining unit of varying thickness. This study explores the karst development within the carbonate layers of the confining unit using geophysical investigation techniques, namely electrical resistivity tomography (ERT), and ground penetrating radar (GPR). Surveys at sites of observed surficial depressions reveal shallow karst development which is unrelated to the deeper karst processes within the Floridan aquifer. The overlying unit, generally comprised of impermeable siliciclastic sediments, appears to have lower degrees of confinement at sites of increased karst development where carbonate layers are present. This has important implications not only for structural stability of the area, but also for the environmental sensitivity of the Floridan aquifer.