Seeing red: Some aspects of the geological and climatic history of the australian arid zone

The iconic Red Centre of Australia broadly corresponds with the driest part of the continent - the Australian arid zone - suggesting that redness is related to aridity. However, the history of redness in Central Australia is longer than that of the Australian arid zone. In this chapter, I describe some aspects of the geological and climatic history of the Australian arid zone that led to its current form. There is palaeobotanical evidence of seasonal dryness from about 40 million years ago, but the first truly arid landscapes, the stony deserts, did not form until 3-4 million years ago, while the oldest dated sand dunes are around 1 million years old. The formation of red rocks and regolith is more constrained by atmospheric oxygen levels than by aridity and may extend back hundreds of millions of years.