Origin of miniature mogotes or mesas in granite, king rocks, southern yilgran block, Western Australia

Abstract

Miniature mogotes occur in profusion on one sector of the western slope of King Rocks, a granitic gneiss bornhardt located in the southern Yilgarn Block of Western Australia. They are remnants of plates delineated by polygonal cracks, which developed at the weathering front. The plates were reduced in area beneath the regolith by seepage from a vegetated basin located on the slope above. The mogotes are the survivors of this process. After the stripping of the regolith and exposure of the bedrock forms, a winding stream further eroded the slope and created a channel devoid of residuals. Raised rims bordering fractures aligned downslope are due to protection afforded by good drainage, and wavy rims trending across slope to induration of biotite-rich foliation layers.