Sandstone terrain in a semi‐arid littoral environment: the Lower Murchison Valley, Western Australia

Abstract

SUMMARY Stream and wave erosion have cut spectacular cliffs in the Tumblagooda Sandstone in the Murchison gorge and along the adjacent coast. The sandplain above the cliffs developed between the Late Cretaceous and the Mid Tertiary but whether it formed at low level and was then uplifted or was formed at its present elevation is not known. The upper 30 km of the gorge post‐dates the laterite on the sandplain. As there is little runoff from the sandplain, erosion is limited to the edge of the gorge. Joints have controlled erosion of small tributaries but have had very limited effect on the course of the Murchison proper. Facies changes within the sandstone are reflected in the form of the cliffs. Very extensive cavernous weathering on the cliffs is attributed to crystallisation of salt. Comparisons with sandstone terrains elsewhere suggest that lithology may be just as important as climate in controlling large‐scale spatial variation of landforms.