What causes the seven coloured earth of chamarel in Mauritius?

I think they are tinted every night to fool tourists [I'm not very sure, though]

Chuck Norris was passing by and accidentally hit a rainbow which fell there creating these colored soils.

HeHe joke

This is due to the different rates of weathering of the different mineral constituents of the volcanic tuffs in the area. (Volcanic rocks are made up of different minerals each one being different in colour and so as the rocks break down, different coloured earths are formed.)