They say White Sands is a beach without the ocean. In fact, it is a dry lake with huge white dunes consisting of gypsum and sand. Wind rubs down the gypsum/sand from the (quite hard) bottom and forms the dunes, sun bakes the surface and thus somewhat stabilises the dunes, but it won't get completely hard like plaster due to the large amount of sand in the mix.

New Mexico, February 2014