A procedure for the rapid and accurate mapping of the depth to the texture contrast horizon of duplex soils was trialled. Data were collected using ground-penetrating radar with a 250 MHz antenna at 4 sites in the Esperance region of Western Australia. The contrast at the B horizon was identified using a ‘picking’ process similar to seismic surveys. The GPS data were integrated and depth to B horizon maps produced by kriging. The results were related to core data taken for sites and showed that GPR can provide accurate and detailed subsurface maps with ±0.1 m accuracy for B horizon depth. The influence of B horizon material composition on GPR response was also investigated using amplitude mapping. The spacing between GPR transects can affect map quality, particularly if the lateral variation in the B horizon depth is not adequately sampled by the line spacing selected. With further integration of the data collection and post-processing procedures, this would prove to be a useful tool for farmers and natural resource managers.