The Arkaroola 4WD Ridgetop Tour
In April 2012 most of the 60,000 hectare Arkaroola pastoral property was made a Protected Area by the South Australian Government. It even has its own Act of Parliament! Why? What is so darned special about this area that this piece of privately owned land should be protected from mining exploitation?
If you really want to find out, the best way is to take a half day Ridgetop Tour. The tours leave at 8am and 1pm daily and is 4-5 hours in duration with several lookout stops along the route. There is a 30min morning/afternoon tea stop at Sillers lookout which includes the world famous “Arkaroola Lamingtons”
The Ridgetop country is amazing. This is the oldest part of the Flinders Ranges, much of it is granite. But the Ridgetop also includes some even more ancient sedimentary rock that was laid down in an ancient sea nearly 1600 million years ago; almost a billion years before much of the rest of the Flinders Ranges was created from sediment collected in a 600 km trough, called the Adelaidian Rift Complex ( formerly known as The Adelaide Geosyncline ), which is represented at the surface as a series of hills, mountains and uplands from eastern Kangaroo Island to just south of Oodnadatta in the far north of South Australia.
The ancient granite terrain starts just north of the Arkaroola Creek and is about 1,580 million years old. This landscape is really wild and rugged, and like other parts of Arkaroola, it contains some plants unknown elsewhere. They are specially adapted to these rock and soil types. Other plants also survive as remnants from wetter periods in history thanks to the relatively cooler and wetter conditions up in the mountains compared to the surrounding semi-desert plains.
The granites were fractured and impregnated with uranium and thorium around 440 Ma (million years) ago. These radioactive elements heated the overlying 12km rock blanket until some of it melted to form another granite body, the Mawson Plateau. The heat also caused an enormous geyser explosion about 299Ma during an Ice Age, with hot pools in the ice and quartz crystals at Mt Gee. This heating phenomenon has not been found anywhere else in the world.
Much of the uranium that once was in Arkaroola has since been dissolved from the rocks and dumped on the eastern plains where it is recovered at the Beverley uranium mine a few kilometres out on the plains below Sillers Lookout.
The Freeling Heights, a magnificent ring of saw toothed blue mountains that fringe the Mawson Plateau, form part of the stunning view you will have at your tea break at Sillers overlooking the 1,000 metre deep Yudnamutana Gorge, Lake Frome salt lake and the plains.