Sydney Basin

The Sydney Basin is both a structural entity and a depositional area, now preserved on the east coast of New South Wales, Australia and with some of its eastern side now subsided beneath the ocean.

It has also lost area on its western side by erosion. Confusion may arise because geologists use the term "Basin" both to mean an area in which deposition is occurring and at other time to mean the rocks formed by that deposition - which are slightly different 'takes' on the matter.

The Sydney Basin consists of Permian and Triassic sedimentary rocks. It is named for the city of Sydney which is centred within it and stretches from Newcastle in the north to Batemans Bay in the south, and west to the Great Dividing Range. The basin is also home to the major centres of Newcastle and Wollongong, and contains economically significant reserves of coal. Sydney’s famous harbour and the sculptured cliffs of the Blue Mountains are signature formations of relatively hard upper strata of sandstone. The basin contains the UNESCO World Heritage-listed Greater Blue Mountains Area.

Definitions of the boundaries and what comprises the Sydney basin vary significantly. The Australian Government classifies the basin as an interim Australian bioregion consisting of 3,629,597 hectares (8,968,930 acres).

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