Figure 2. Excerpts of a 200-MHz GPR profile collected over the western flank of a dune in the Namib Desert. Excerpts of data are shown encircled. For depth conversion we used a dielectric constant of 6 (0.12 m/ns), yielding a vertical resolution of 15 centimeters. A dielectric constant of 6 is similar to values used previously for dunes in the Namib Desert and is consistent with a dry, quartz sand deposit.