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'. These are a 26 km long series of lunettes, about 30 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 between 25,000 and 15,000 years ago.