Bornhardt inselbers in the Salt River Valley, south of Kellerberrin, Western Australia (with notes on a tesselated pavement in granite and pinnacles in laterite)

Abstract

Several prominent bornhardts, or dome-shaped granitic hills, occur in or near the valley of the Salt River, south of Kellerberrin, Western Australia. They originated as subsurface bedrock rises projecting into the base of a regolith produced by fracture-controlled weathering beneath a lateritised land surface in Cretaceous and earlier Mesozoic times. They were exposed during the Early Cainozoic by the stripping of the regolith by a rejuvenated Salt River and its tributaries. By the Miocene, the river had cut a bedrock gorge below the present valley, but this has since been infilled and buried. Some effects of weathering by and in the lateritic carapace are noted.