Geology
Sediments at Lake Mungo have been deposited over more than 100,000 years. On the eastern shore of the lake are the 'Walls of China', a 26 km long series of lunettes, about thirty metres high, formed over thousands of years. There are three distinct layers of sands and soil forming the Walls. The oldest is the reddish Gol Gol layer, formed between 100,000 and 120,000 years ago. The middle greyish layer is the Mungo layer, deposited between 50,000 and 25,000 years ago. The most recent is the Zanci layer, which is pale brown, and was laid down mostly between 25,000 and 15,000 years ago.
The Mungo layer, which was deposited before the last ice age period, is the most archaeologically rich. Although the layer corresponded with a time of low rainfall and cooler weather, more rainwater ran off the western side of the Great Dividing Range during that period, keeping the lake full. It supported a significant human population, as well as many varieties of Australian megafauna.
During the last ice age period, the water level in the lake dropped, and it became a salt lake. This made the soil alkaline, which helped to preserve the remains left behind in the Walls of China. Although the lake completely dried up several thousand years ago, ground vegetation remained on the Walls, which helped to stabilise them and preserve them. With the arrival of European settlers in the area since the 1880s, introduced species, notably rabbits and sheep, have destroyed the vegetation cover. Herds of feral goats are also present in the region. This has led to increased erosion of the dunes. However, this erosion has led to the uncovering of many human and animal remains. Wind has moved sand and soil eastwards from the Walls, forming a mobile sand dune which moves further east every year.
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