Engineers Australia

The geomorphology of the Perth region, Western Australia

Karl-Heinz Wyrwoll

Abstract

An overview of the geomorphology of the wider Perth region is presented in the context of issues relevant to geotechnical engineering. The region is divided into the erosional terrains of the Darling Scarp and the Cenozoic depositional landforms of the coastal plain. Attention is drawn to claims of possible neotectonic activity associated with the Darling Fault, and the likely geomorphological expression of recent events. The soil, geomorphological and stratigraphic divisions of the Cenozoic coastal deposits are discussed, and the importance of the Tamala Limestone is stressed. The stratigraphic and geomorphological details of the coastal sequences are provided and evaluated in the context of global Late Cenozoic sea-level events. The alluvial deposits of the coastal plain are described and an overview of the controls on deposition and the resultant alluvial architecture is provided. The stratigraphic architecture of both the coastal and alluvial deposits has important implications for hydrogeology and contaminant movement. In closing, the paper draws attention to specific geomorphological events and processes of direct relevance to geotechnical engineering, which may not have received sufficient attention.