Figure 1. Left (a), 400-MHz GPR profiles from Andros Island. Letters indicate reflective domains referred to in the text and in Figure 1b. Depth conversion was based on a dielectric constant of 18.4 (0.07 m/ns). This provides a vertical resolution of 4-5 centimeters. These and subsequent profiles were processed using software generously provided by a Landmark (Halliburton) university grant. Middle (b), depth slice averaged over 0.1 m depth from GPR 3-D volume in Andros with location of profiles A and B noted; right, same as middle, but with no vertical averaging, which provides enhanced precision.