Arkaroo Rock car park is located 3 kilometers off Flinders Ranges Way, along the Arkaroo Rock Road and about 40 kilometers north from Hawker.
Arkaroo Rock is a significant site for the Adnyamathanha people. The paintings depict aspects of the Muda (Dreaming) for Ikara (Wilpena Pound). One of the Dreaming Ancestors was Akurra, a powerful water snake who created many features of the Ranges landscape. The bodies of two Akurras from the walls of the Wilpena Pound.
In the Adnyamathanha Yura Muda, the unformed land was shaped by the Akurra, an immense maned and bearded water snake. Two Akurras, a male and a female, feature in the creation history for Wilpena Pound while the regions earth tremors are explained as rumblings from Akurra's water-filled belly. The activities of travelling ancestral spirits further shaped the land. The White-winged Fairy-wren threw a boomerang which created the cleft in Mount Chambers. An argument between a Euro and a Red Kangaroo led to the creation of the rocky northern Flinders Ranges, separated from Lake Frome by the sweep of the kangaroo's tail. Waterholes and springs along the eastern side of the ranges were created by the Thumping Kangaroo. Land, rocks and minerals are all manifestations of the Yura Muda.
Aboriginal Engravings
Geologists use science to explain how the Flinders Ranges were formed. The Adnyamathanha people of the Flinders Ranges have their own creation histories for the land and the life it supports. The creation histories and geology complement each other, enriching our knowledge of the landscape.
Scientists believe that the Flinders Ranges began to form about 800 million years ago when a great depression, known as the Adelaide Geosyncline, developed as the earth's crust stretched and thinned. The sea flooded in and, for 300 million years, huge amounts of rock debris, stripped from the land was deposited in the deepening depression to thicknesses of many kilometres.
About 500 million years ago the rock layers were squeezed and folded into a long mountain chain, much higher than today's ranges. The great bulk of the ancestral Flinders Ranges was then eroded over millions of years. Resistant quartzite now forms the highest peaks and ridges of the Flinders Ranges while the softer mudstone, siltstone and shale have been worn away to form valleys and gorges. Occasional earth tremors today indicate that the mountains continue to be uplifted.
Flinders Ranges from the the sky
The area is part of the Adelaide Geosyncline. Despite early amateur theories that it was some kind of ancient volcano, the actual Pound is sedimentary rock in the form of a large syncline, with the fold axis running NNW-SSE through Edeowie Gorge at the northern end and Rawnsley's Bluff at the southern. A corresponding anticline is located in the adjacent Moralana Gorge, with the Elder Range on the downturned western limb. The area has given its name to the Wilpena Group of sedimentary rocks making up the younger sediments of the geosyncline, and names of further subdivisions also originate from the area: particularly the Pound Subgroup, made up of Rawnsley Quartzite and Bonney Sandstone, which were laid down during the Ediacaran Period.
In structural geology, a syncline is a fold with younger layers closer to the center of the structure. Synclines are typically a downward fold, but synclines that point upwards, or perched, can be found when strata have been overturned and folded (an antiformal syncline).
Antecline & Syncline
Quartzite is a hard, non-foliated metamorphic rock which was originally pure quartz sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of iron oxide. Other colors, such as yellow, green, blue and orange, are due to other mineral impurities. When sandstone is cemented to quartzite, the individual quartz grains recrystallize along with the former cementing material to form an interlocking mosaic of quartz crystals.
Quartzite
These questions can be answered when you reach Arkaroo Rock and follow the circle trail back to the car park.
Questions
Q1 At the posted coordinates, describe the inside of the rock (where the engravings are) in colour and texture.
Q2 Stage 2 will bring you to a another significant rock. Describe the outside of the rock and compare it to the cut out. What would you compare the 'shell' to (anything that comes to mind).
Q3 Stage 3 will take you to another large rock. Describe the colour and texture of the wall that the coordinates brings you to. Does it differ to the others?
Q4 Quartzite is a hard, non-foliated metamorphic rock which was originally....?
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References ~ australiannationalparks.com, walkingsa.org.au, Wikipedia