The origin of the Loe hole of Matsieng

The Loe hole of Matsieng, one of the best preserved Tswana 'creation' sites, and the large hole adjacent to it, are excellent examples of gnammas, formed by a two-stage weathering process. The first is one in which weathering penetrated the parent Waterberg sandstone irregularly, to give a sharp but gently undulating basal surface of weathering. Humid conditions are implied. Following a climatic change towards greater aridity and a more seasonal climatic regime, the overburden was removed, exposing the undulating fresh rock. The relatively minor depressions became deepened and enlarged under subaerial conditions. Water retention in the depressions promoted aggressive weathering within them, bio-corrosion being implicated as a major process.