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The Seven Coloured Earths, Mauritius

The Seven Coloured Earths, a geological formation and a major tourist attraction found in the Chamarel plain of the Rivière Noire District in south-western Mauritius. It is a relatively small area of sand dunes is covered in surreal stripes of blue, yellow, purple, red, brown, green and violet. The main feature of the place is that since these differently coloured sands spontaneously settle in different layers, dunes acquire a surrealistic, striped colouring. This phenomenon can also be observed, on a smaller scale, if one takes a handful of sands of different colours and mixes them together, as they'll eventually separate into a layered spectrum. Another interesting feature of Chamarel's Coloured Earths is that the dunes seemingly never erode, in spite of Mauritius' torrential, tropical rains.

Image Credit Allan Beaufour

The ~7500 m2 is a small area of strikingly bare landscape showing well-developed rills and various shades of red, brown, grey, and purple. Curiously, it is located within a large, dense forest. Prevalent misconceptions are that the landscape formed due to a volcanic eruption, or from volcanic ash. Whereas the bedrock is undoubtedly an old volcanic rock "basalt", the colors are due to weathering of the basalt and the formation of secondary iron oxides and hydroxides in it, and the rilling is a result of deforestation and sheet erosion, i.e., human modification of the landscape. Such features, inadequately described in the literature so far, also occur in Papua New Guinea, and may be common in tropical, high-rainfall regions with volcanic bedrock. [source]

The place has become one of Mauritius' main tourist attractions since the 1960s. Nowadays, the dunes are protected by a wooden fence and visitors are not allowed to climb on them, although they can look at the scenery from observation outposts placed along the fence. Curio shops in the area sell small test-tubes filled up with the coloured earths. [source]