Near Mount Liptrap, north and west of Walkerville, are areas where sand from the dunes to the west have been blown eastwards. This has formed a shallow mantle of sand over the original soil. The sand mantle covers the Inverloch mapping unit (Tertiary sediments) and the Kongwak mapping unit (Palaeozoic sediments).
Inverloch sand overlay has a very dark grey loamy sand surface soil (about 30 cm deep) overlying light grey sand. Mottled light grey and yellowish brown light to medium clays abruptly occur usually before 80 cm.