Top spot for an over nighter, I bobbed in on the way back from the Anne Beadell........
Pildappa Rock is a unique pink inselberg located 15 kilometres northeast of Minnipa. Situated in South Australia's granite country, locals proudly proclaim Pildappa to rival the more famous "Wave Rock" - a sandstone wave form located in Hyden Western Australia.
Formed about 1500 million years ago Pildappa Rock is part of the vast Gawler Craton - a geological shield structure covering central Eyre Peninsula, the Gawler Ranges and large parts of outback South Australia. Geologists refer to Pildappa Rock and other inselbergs in the area as belonging to the Hiltaba suite of rocks - basically orthoclase rich pink granites dating from Eyre Peninsula's Precambrian age.
Nearby the Gawler Ranges were formed as a result of volcanic action. Unlike the Gawler Ranges however, Eyre Peninsula's inselbergs were formed as Batholiths or granite domes some 7 kilometres below the earth's surface. Clearly much soil erosion has occurred during the past 1500 million years. Equally remarkably, Pildappa Rock and many other Australian inselbergs exhibit very slow rates of weathering - with numerous studies indicating exposed granite surfaces eroding at rates below 50 centimetres per million years.
Geologists believe the process of flare formation typically involves water runoff seeping into the soil at the base of granite rock faces. Over time, water and permanently moist soil conditions act together to chemically weather away highly reactive granite minerals such as orthoclase and mica. All this can take place at depths of up to 30 metres below the surface. In the case of Pildappa Rock soil levels have also gradually eroded away thereby exposing the prominent flare structure that we can see today.
Text from Nullabor net..
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Originally Posted by Plasnart
