What happens is that the wind blows the sand up the shallow slope on the other side, and then, as each sand grain hits the top of the ridge, it cascades down on the inside of the crescent, and so the whole horn-shaped dune moves.
O vento sopra a areia declive acima até o outro lado, e quando os grãos de areia chegam ao cume, eles caem do outro lado da meia-lua, fazendo toda duna se mover.