Great Artesian Basin

The Great Artesian Basin, located in Australia, is the largest and deepest artesian basin in the world, stretching over 1,700,000 square kilometres (660,000 sq mi), with measured temperatures ranging from 30–100 °C (86–212 °F). The basin provides the only source of fresh water through much of inland Australia.

The Basin underlies 23% of the continent, including the states and territories of Queensland (most of), the Northern Territory (the south-east corner of), South Australia (the north-east part of), and New South Wales (northern part of). The basin is 3,000 metres (9,800 ft) deep in places and is estimated to contain 64,900 cubic kilometres (15,600 cu mi) of groundwater. The Great Artesian Basin Coordinating Committee (GABCC) coordinates activity between the various levels of government and community organisations.

This area is one of the distinct physiographic provinces of the larger East Australian Basins division, and includes the smaller Wilcannia Threshold physiographic section.

The water of the GAB is held in a sandstone layer laid down by continental erosion of higher ground during the Triassic, Jurassic, and early Cretaceous periods. During a time when much of what is now inland Australia was below sea level, the sandstone was then covered by a layer of marine sedimentary rock shortly afterward, which formed a confining layer, thus trapping water in the sandstone aquifer. The eastern edge of the basin was uplifted when the Great Dividing Range formed. The other side was created from the landforms of the Central Eastern Lowlands and the Great Western Plateau to the west.

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