ABSTRACT
The principal physiographic units within the Sydney region are the Cumberland Plain and the Hornsby Plateau. Most of the recent inland alluvial deposits in the Sydney region occur on the Cumberland Plain. These alluvial deposits commence at about Chullora and extend downstream through Canterbury and Arncliffe, with the river outlet into Botany Bay just south of Mascot airport. The two major tributaries of the Cooks River are Wolli Creek, which feeds from Earlwood in an easterly direction towards Tempe, and a now infilled tributary which once flowed in a south-westerly direction from Marrickville towards Tempe; this infilled tributary covers much of the area of Marrickville and Sydenham. The Georges River is the major drainage course for the south-western portion of Sydney. The main tributaries to the Parramatta River are Toongabbie Creek, which generally contains few organic deposits and consists of reasonably competent alluvial soils, and Duck River which feeds the Parramatta River from as far south as Chester Hill.
