Cumberland Plain. Though there are a few hilly or relatively elevated regions on the plain. Western Sydney Parklands and the surrounding suburbs (such as Cecil Hills and Horsley Park), for instance, lies on a prominent ridge that is between high. Bringelly Shale and Minchinbury Sandstone are often seen in the Plain's west. Ashfield Shale is observed in the inner western suburbs. These components are part of the Wianamatta Shale group. Rivers Rivers in the Cumberland Plain are salient. The Nepean River rises to the south in the Woronora Plateau, and wraps around the western edge of the city. Parramatta River's headwaters are several local creeks including Toongabbie Creek and Hunts Creek, part of the upper Parramatta river catchment area. Hunt's creek flows from Lake Parramatta, a few kilometres North of Parramatta. Warragamba River flows north-east from the Warragamba Dam spillway to its confluence with the Nepean River. The south and southwest of Sydney is drained by the Georges River, flowing north from its source near Appin, towards Liverpool and then turning east towards Botany Bay. The other major tributary of Botany Bay is the Cooks River, running through the inner-south western suburbs of Canterbury and Tempe. The Georges River estuary separates the main part of Sydney's urban area from the Sutherland Shire. The Woronora River, on the southern edge of the Sydney Plain, flows in a steep-sided valley from the Woronora Dam to the eastern estuary of the Georges River. Minor waterways draining Sydney's western suburbs include South Creek and Eastern Creek, flowing into the Hawkesbury, and Prospect Creek draining into the Georges River. Ecology Flora The most predominant plant communities in the Cumberland Plain are grassy sclerophyll woodlands, with over 830 native species. Dry and wet sclerophyll forests generally lie on the Hornsby plateau, an elevated region north of the Plain. Dry sclerophyll forests contain eucalyptus trees which are usually in open woodlands that have dry shrubs and sparse grass in the understory. In 1820s, Peter Cunningham described the country west of Parramatta and Liverpool as "a fine timbered country, perfectly clear of bush, through which you might, generally speaking, drive a gig in all directions, without any impediment in the shape of rocks, scrubs, or close forest". This confirmed earlier accounts by Governor Arthur Phillip, who suggested that the trees were "growing at a distance of some twenty to forty feet from each other, and in general entirely