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The Great Artesian Basin
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| When white pioneers set out to explore Australia's interior, they thought they would find an ' inland sea ' . As it turns out they were only partly wrong. Early explorers were devasted to find an apparently 'impassable' horseshoe of salt lakes. But beneath the surface lays an ancient water source that now sustains wildlife; a significant pastoral industry and a thriving tourism industry. |
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| The Great Artesian Basin (GAB) is one of the world's largest underground water reservoirs, with an estimated 64,900 million megalitres of water storage. Underlying 22% of Australia, the Basin formed between 100 and 250 million years ago. |
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Water enters the basin in 'intake beds' on the western edge of the Great Dividing Range on Australia's east coast, and slowly flows downwards at an average of less than three metres a year. It is estimated that water currently coming out at tyhe south western end of the GAB is around two million years old.
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The Oodnadatta Track lies on the western margins of the Great Artesian Basin. In many places the Basin water has squeezed to the surface in the form of natural springs. Many of the GAB springs are known as 'mound springs' because of the characteristic mounds associated with them. The mounds have been formed by mineralised material coming to the surface with the ancient water. You can also see extinxt mound springs along the track, most notably at Hamilton Hill and Beresford.
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There are more that 1,700 individual springs in 23 complexs found within the South Australian part of the GAB. The largest group is the renown Dalhousie complex, where more than 60 springs are located. Most springs are not 'moundsprings' but small inconspicuous soaks in the ground. The water of the GAB is generally alkaline and saline with high concentrationsof dissolved solids such as carbonates, sulphates and chlorides.
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Many of the springs have great signifigance for the local Aboriginals whose ancestors relied on them as watering points and as sacred sites for important ceremonies. There are many Dreamtime stories associated with the Springs. Emerald Springs and Blance Cup were the first GAB springs to be located by the white explorers.
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Another standout feature on the Oodnadatta Track is the Algebuckina Waterhole. This waterhole has never dried up in living memory. It is the largest refuge waterhole in the Neales-Peake river system and crucial to the survival of both wildlife and stock.
The Neales is one of the western rivers of the Lake Eyre Basin. The rivers and creeks of Lake Eyre are considered to be some of the last 'wild' river systems in the world. These rivers are capable of extreme variability in flow - generally short periods of high flow following rain and extended periods of no flow. The Neales has small flows most years, and experiences large floods every 7-10 years.
The enormous Algebuckina Bridge demonstrates the extent of flooding possible in this region and the enigeering feats necessary to construct the railway around such flood conditions.
These waterholes and springs opened the way for European settlement and by 1859 the first pastoral leases were established in this region.
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Information Courtesy of
Arid Areas Catchement Water Board
Government of South Australia
South Australian Tourism Commission
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