Formation of the Pinnacles: Soil and Calcrete Formation
Step 2: During the Pleistocene, the climate in Western Australia was very Mediterranean. This climate is typified by cool wet winters and hot dry summers. During the wet winters, rain dissolved and leached the calcite from the upper levels of the dunes and precipitated the calcite as cement in lower levels of the dune. Plants began to grow on the surface and produce an acidic, humus rich layer which accelerated the leaching process. At the base of the soil horizon, a layer of calcrete formed effectively isolating the lower portion of the dunes from the surface layer.