Outback stands for the vast, dry, sparsely settled territory beyond the areas of local government. Few South Australians have experience of the Outback, except what they may see as travellers on the Barrier Highway to Broken Hill, the Eyre Highway to Perth, or the road to Coober Pedy opal field.
The Outback, including the Flinders Ranges, is about 85% of the State's area and yet had only 0.75% of its population in 1981. In that year it contributed 4.7% of the value of the State's farm output.
From E.J. Eyre's first expedition in 1839 until the end of the nineteenth century, the arid interior offered fascination, challenge and ultimately disappointment to South Australians. Early hopes of finding rich resources were seldom fulfilled. By 1890, much of the central areas were grazed, as it still is, sparsely. Mining, mostly of recent discoveries, now yields more income than pastoralism.
The region has three major deserts. Sturt Stony Desert in the north-east is a vast extent of small round stones or gibbers. The Simpson Desert, which extends into the State from the Northern Territory and Queensland, consists of long parallel dunes of red sands. In the west, The Great Victoria Desert is an extension of the Western Australian shield of ancient rocks eroded to a surface of gently undulating gibber plains, salt-pans and sand-ridges.
In the centre of the region, low hills and gently sloping plains extend from the Flinders Ranges to the deeply weathered Musgrave Ranges in the far north-west. Here is the highest point in the State - Mount Woodroffe, at 1435 metres. Bordering the Ranges are a number of extensive salt lakes which seldom hold water and normally appear as depressions with a clay or salt encrusted surface.
The Outback's annual rainfall is low and extremely variable. Mean annual falls range from 250 mm to less than 150 mm in the Lake Eyre Basin, the driest part of the Australian continent. Much of the pastoral land is shrubland of saltbush and bluebush, or open woodland of mulga. Some areas have not yet recovered from severe over-grazing during the late nineteenth and early twentieth centuries.
A distinctive feature of the Outback is the line of mound springs extending in a great arc from the ruined Dalhousie homestead north of Oodnadatta south-east to Lake Frome. These springs, some flowing, others extinct, mark the approximate south-western edge of the Great Artesian Basin and are suitable for stock watering. For thousands of years they provided reliable water for Aborigines. In European times they influenced the routes of early exploration, and the citing of pastoral homesteads and some of the repeater stations on the Overland Telegraph.
The western part of the region is remote and sparsely populated. After the Second World War, British and Australian governments used it to test rockets and atomic weapons. Since 1948, activities have been based at Woomera (population 1658 in 1981), and a restricted area of 130,000 square kilometres established for trials, exercises and training. Narrungar, a joint United States-Australian Defence Space Communications Station at Island Lagoon near Woomera, is said to play an important part in monitoring Soviet defence systems.
The central and eastern part of the Outback has seen important mining developments in this century. Coober Pedy (population 2078). Australia's largest opal field was discovered in 1915 and attracts thousands of visitors each year. Almost two million tonnes of coal per year is mined from the Leigh Creek district. Natural gas comes from the Cooper Basin in the far north-east where more than 100 exploration and production wells have been drilled since 1963. A huge mineral resource was identified in 1975 by Western Mining Corporation Ltd at Olympic Dam on Roxby Downs pastoral station. It may become a major world supplier of copper, uranium, gold and rare-earth metals if market conditions allow.