The Burrup Peninsula and surrounding Dampier Archipelago, in Western
Australia, contain the world's largest known gallery of rock art
engravings (petroglyphs), estimated to number up to 1 million images.
The peninsula is also the site of major industrial development and there
are concerns that industrial emissions may adversely affect the
stability and longevity of the rock art. We have studied
... [Show full abstract] the natural
processes and rates of weathering and erosion, including the effects of
fire, that affect the stability of rock surfaces and hence the longevity
of the rock art, using cosmogenic nuclides. The concentration of
10Be in quartz yields erosion rates in the range
0.15-0.48 mm/1000 years on horizontal rock surfaces and
0.34-2.30 mm/1000 years on vertical rock faces. The former,
largely caused by mm-scale surface flaking, are amongst the lowest
erosion rates measured by cosmogenic nuclides anywhere in the world. The
latter are inferred to represent a combination of mm-scale flaking and
very rare centimetre- to metre-scale block falls, controlled by failure
along joint planes. Such low erosion rates result from a combination of
resistant rocks, low relief and low rainfall, favouring long-term
preservation of the petroglyphs - long enough to encompass the
known period of human settlement in Australia.