Ground-penetrating radar mapping in clay: Success from South Carolina, USA

A ground-penetrating radar (GPR) survey conducted in a clay-rich floodplain of the Savannah River, South Carolina, produced what were very difficult to interpret reflection profiles caused by energy coupling changes. These changes were caused by deep hardened plow furrows at the ground surface that caused antenna movement to be irregular, and energy to be transmitted into the ground at various angles, and with different properties. A dense clay layer also attenuated much of the radar energy at about 50 cm, further obscuring the profiles. Despite these ambiguous data, amplitude mapping at slices below the clay layer yielded images of distinct circular and linear features, which proved to be palisade walls dating from about the late Mississippian to Early Contact period (AD1400-1740).This survey illustrates that it is possible to obtain good GPR results even when energy passes through dense clay and when reflection profiles are obscured by attenuation and coupling changes. Copyright (c) 2006 John Wiley & Sons, Ltd.