Cumberland Plain

About

The Cumberland Plain, also known as Cumberland Basin, is a relatively flat region lying to the west of Sydney CBD in New South Wales, Australia. An IBRA biogeographic region, Cumberland Basin is the preferred physiographic and geological term for the low-lying plain of the Permian-Triassic Sydney Basin found between Sydney and the Blue Mountains, and it is a structural sub-basin of the Sydney Basin.

The Cumberland Plain has an area of roughly 2,750 square kilometres (1,060 sq mi), which lies on Triassic shales and sandstones. Shaping the geography of Sydney, it extends from 10 kilometres (6.2 mi) north of Windsor in the north, to Picton in the south; and from the Nepean-Hawkesbury River in the west almost to Sydney City, and includes parts of the Inner West and Northern Suburbs in the east. Much of the Sydney metropolitan area is located on the Plain. The Hornsby Plateau is located to the north and is dissected by steep valleys.