The Central Lowland of Australia

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The Central Lowland of Australia includes the gently sloping western flank of the Eastern Highlands and also the low-lying basins tributary to the Gulf of Carpentaria on the north and to Spencer Gulf on the south. An area of about a million square miles or onethird of the continent is included; most of it lies below the 500-foot contour, and nearly all is less than 1000 feet above sea level.

The Central Lowland experienced no major geologic change in recent times as did the Eastern Highlands. Large amounts of alluvial material have been brought down by streams from the adjoining uplands and deposited over its ancient surface. Winds have moved much of this material about from place to place. The northermost part of the Central Lowland has been submerged to form the Gulf of Carpentaria. Its margins are shallow and muddy and should be avoided by even small ships. The southern end of the Central Lowland has likewise undergone partial submergence, and Spencer Gulf and the Gulf of St. Vincent penetrate deeply in the direction of Lake Torrens and Lake Eyre. Lake Eyre has an elevation of 39 feet below sea level.

The Central Lowland is divided into several drainage basins by low saddles or uplifts that connect the Eastern Highlands with the Western Plateau. The Cloncurry ( Mt. Isa) uplift separates the drainage area tributary to the Gulf of Carpentaria from the Lake Eyre basin. In similar fashion the Cobar-Broken Hill uplift separates the Darling River basin from that of the Murray River in the south. The Great Artesian Basin underlies all the Central Lowland to the north of the Cobar-Broken Hill uplift. It includes an area of 550,000 square miles and is the greatest example of its kind in the world.

The Mt. Lofty-Flinders Range extends northward from Adelaide for a distance of nearly 400 miles, thus further separating the DarlingMurray rivers basin from the Spencer's Gulf-Lake Torrens subdivision. The area tributary to Lake Eyre is extremely dry, and much of the watershed of the Darling River is likewise subjected to arid-land erosional processes. Even the Murray River and its important tributaries, the Murrumbidgee and Lachlan, are unable to carry the loads of sediment that reach their courses. As a consequence, their channels shift about continuously through the intricate maze of "billabongs" (anabranches), swamps, and marshes that parallel the drainage courses.