Darling Scarp - Geology

Geology

The Darling Scarp originated as the local expression, in the Perth area, of the extensive Darling Fault, a major and ancient geological discontinuity separating the Archaean Yilgarn Craton in the east from the younger Pinjarra Orogen and overlying Phanerozoic Perth Basin to the west. The Darling Fault is exposed for over 1,000 km, from the area east of Shark Bay, to the southern coast of Western Australia east of Albany. The location of the scarp must once have coincided with the location of the fault, but the scarp has since eroded about 15 kilometres eastwards. The original location of the scarp is indicated in places by an unusual landform known as the Ridge Hill Shelf.

The Archaean granites and gneisses of the Yilgarn Craton form the high ground of the Perth Hills and can be observed in road cuts, with good examples in the Mundaring Weir area. The only exposed sediments of the Perth Basin, west of the fault, are of Cenozoic age, and comprise the material such as sandy limestone, travertine and dune sand on which the city of Perth is built, including sand dunes of Pleistocene age formed during the last Ice Age.

This area is also a distinct physiographic section of the larger Yilgarn Block province, which in turn is part of the larger West Australian Shield division.