Stephen Hack explored the range in 1856 and in 1857 the first pastoral lease was taken up in the area,[5]Yardea, which was set up on the site of a former Aboriginal camp and included a freshwater spring later used as the station's water source. More sheep stations were soon established, including Hiltaba and Paney Station.[2] Two good seasons followed in 1857 and 1858, with pastoralists reporting permanent freshwater lakes on their runs. Stations were required to stock 50 sheep per square mile (19 per square kilometre) but soon properties such as Nonning were shearing flocks of 90,000.[5]
The first mail service from Port Augusta to Yardea commenced in 1876, with the telegraph service to Western Australia that passes through the range commencing in 1903[5]
Geology
Pink granite at Hiltaba Nature ReserveAcraman Salt Lake with Gawler Range in backgroundConical Hill Track in the Gawler Range
The rocks within the ranges were formed by volcanic activity between ~1595-1592 Ma, when the Gawler Range Volcanics (GRV) were erupted.[6] Approximately 30 000 km3 of dominantly rhyolitic and daciticlava were rapidly extruded, and their eroded remnants preserve one of the most voluminous felsic magmatic events preserved on earth. Basaltic and basaltic-andesite comprise a remarkably minor component of the magmatism (<1%). The Gawler Ranges Volcanics were also erupted at remarkably high temperatures (~950-1100 °C) for felsic magmas, and this, coupled with their very high halogen (particularly F and Cl) compositions resulted in low viscosity (runny) magmas when compared to typical rhyolites and dacites which are generally several hundred degrees cooler. This low viscosity resulted in emplacement as a series of lobate flows with a stacked pancake-like morphology which cooled rapidly resulting in porphyritic textures and widespread columnar jointing. The ranges are a small part of the Gawler Craton which is a craton rich in mineral resources, although many are only recently discovered and not yet fully exploited.[citation needed]
At approximately 580Ma the Gawler Ranges were impacted by a large meteorite which excavated the Acraman impact crater, in which the modern Lake Acraman now sits. The original crater was possibly as large as 90 km in diameter and flung fist-sized debris several hundred kilometres to the east, where it has been preserved in sediments which now comprise the Flinders Ranges.[citation needed]
Geomorphology
The highest point is Nukey Bluff at 465 metres (1,526 ft) above sea level.
Bornhardts dominate the landscape.[8] Soils are invariably dominated by the weathering products of the volcanics, and are typically red in colour due to abundant oxidised iron weathering in the arid environment. No major rivers drain the ranges, however several internal catchments feed the modern playa lakes Gairdner, Acraman, Everard, McFarlane, Harry and Island Lagoon.
^Pankhurst et al., 2011 A Mesoproterozoic continental flood rhyolite province, the Gawler Ranges, Australia: the end member example of the Large Igneous Province clan
^Deborah Furbank (2010): Briefing note on the Southern Hairy-nosed Wombat. Yorke Peninsula Natural Resource Management Group PDFArchived 2012-03-25 at the Wayback Machine
