Research has shown that the water can take up to 1.5 to 2 million years to travel from the recharge areas in eastern Queensland to the discharge areas around Lake Eyre in SA, which means that the water in this region is fossil water. Arrows represent water flow paths. Due to the size and complexity of the GAB, it supports many spring complexes where the groundwater is forced to the surface. The south-western region of the GAB around Lake Eyre contains the largest number of active and unique springs. Some springs have characteristic mounds which have been formed by the combined action of water, sand, silt and clay and the deposition of limestone from the groundwater.
Arrows represent water flow paths.
Due to their isolation in the desert over many millennia, they have developed unique ecology with many rare and endangered species of flora and fauna. The springs form wetlands and small creeks, with the size being dependent on the flow rate from the spring. These wetlands are important in the ecology of the arid lands, and are especially important in times of drought. As the primary source of water for the interior of Australia, the springs were important centres for Aboriginal communities. This is demonstrated by the large abundance of stone chips, grinding stones and other artefacts in their vicinity.