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The Painted Desert in South Australia is an area of coloured clays with white, orange, yellow and pink predominating. There are also mesa formations with
a layer of red brown rock often protecting the softer underlying clay from weathering. Broken, angular pieces of rock lie
around on the surface. Vegetation is sparse in this arid region with an average rainfall at nearby Oodnadatta (closest site with
long-term weather records) of 173 millimetres a year. Hottest
month is January with average maximum of 38°C. Coolest month is July with average maximum of 20°C.
There can be confusion between the Painted Hills and the Painted Desert. Both are in South Australia; the name Painted Desert has been applied to coloured hills around Mt Arckaringa and the Arckaringa Floodplain south west of Oodnadatta while the term Painted Hills, which seems equally suitable to the Mt Arckaringa area, has been applied to similarly coloured hills in the Woomera Prohibited Area. The Painted Hills can be viewed only from an aircraft as public access into the Prohibited Area is not available, while the Painted Desert was declared as the Arckaringa Hills State Heritage Area in 1985 and can be reached by 4WD vehicle on dirt and gravel roads.
The State Heritage Area is bounded by 27° 42' 00"S, 27° 56' 00"S, 134° 36' 00"E and 134° 57' 00"E. The southern boundary runs close to Arckaringa Homestead and the road from Cadney to Oodnadatta passes through the southern part of the heritage area. According to the heritage documentation the Arckaringa Hills State Heritage Area is geologically significant as a site illustrating the effects of prolonged weathering and is a striking example of Badlands or Breakaway topography where the dissected plateau of Cretaceous mudstone and younger rock displays a range of strata coloured red, brown and yellow oxides in the eroded escarpments.
There are no facilities in the Heritage Area. Camping is available at nearby Arckaringa Homestead.
|The road from Cadney Homestead Roadhouse (on the Stuart Highway) to Oodnadatta passes the turnoff to Arckaringa Homestead 82 kilometres from Cadney. About nine kilometres further on a Public Access road off to the left (when heading towards Oodnadatta) goes along a line of outcrops to a carpark from which a walking track goes to the top of Mt Arckaringa.|
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The road to Oodnadatta continues to a lookout east of Mt Arckaringa which the Heritage Documentation calls a "...lookout east of the Public Access Route..." but which bears the less mundane local name of Mt Batterbee on a rough sign at the lookout.
Mt Batterbee (27° 53' 44"S, 134° 51' 10"E, elevation 196 metres) lookout has spectacular views onto the Painted Desert; the visitor can see south-west across the floodplain of Arckaringa creek or north-west to Mt Arckaringa and associated mesa outcrops. Immediately below the lookout, white clay slopes runs down to dry creekbeds with sharp, broken brown stones and boulders covering the ground or gathered in piles.
The explanation for this terrain lies millions of years in the past when the region was wetter and silica minerals in the soil were dissolved in water and subsequently precipitated as a solid. One explanation is that monsoon rainfall dissolved the silica then evaporation during succeeding dry seasons caused the dissolved silica to precipitate as silcrete but there are other theories. What is clear is that the silica was deposited as silcrete in layers up to several metres thick.
Silcrete is extremely hard and resists chemical weathering. Once formed, the silcrete layer protected the underlying, softer, material from weathering and erosion for hundreds of thousands of years. Eventually, large scale earth movement cracked the silcrete layer and weathering processes began breaking up the silcrete, washing away the now exposed softer underlying material. Removal of the underlying material, which was supporting the silcrete, hastened the break-up.
The Painted Desert is the outcome of these processes with rounded, eroded outcrops of soft coloured clays and the residue of the former protrective silcrete layer; a silcrete cap is still protecting some parts of softer clay but much of the silcrete has been broken up and is now piled on slopes and valleys. The brown colouring on photographs of the Painted Desert is piled broken silcrete.
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¶ http://www.environment.sa.gov.au/heritage/shas/sha_arckaringa.html accessed 13 Dec 09.
¶ Buraeu of Meterology at http://www.bom.gov.au - accessed 13 Dec 09.
¶ http://http://www.environment.sa.gov.au/heritage/pdfs/surveys/oodnadatta/part_2.pdf - accessed 13 Dec 09.
¶ Soil Formation by N. van Breemen, P. Buurman, Google Books - accessed 13 Dec 09.
¶ Geomorphology of Desert Environments By A. J. Parsons, A. D. Abrahams, Google Books - accessed 13 Dec 09