As here in Enneri Blaka, Niger, the sand is constantly abrading the sandstone against which it is violently hurled by the wind. Swollen by the material it has loosened, it enriches the dunes of the great erg. Over time, however, the sand from which the dunes are formed begins to solidify and become sandstone again! This is an unexpected form of self-regeneration.
As here in Enneri Blaka, Niger, the sand is constantly abrading the sandstone against which it is violently hurled by the wind. Swollen by the material it has loosened, it enriches the dunes of the great erg. Over time, however, the sand from which the dunes are formed begins to solidify and become sandstone again! This is an unexpected form of self-regeneration.