There is an interesting phenomenon that can be observed at Eureka Dunes. From a distance, the sand appears to be plain gray. At a closer look, though, youŽll find that the dunes consist of two different sorts of sand grains: dark, anthracite colored ones and a second sort that is light gray. The amazing thing is that there must be some physical parameter distinguishing both (density, I guess) which prevents them from forming the uniform mixture you would expect to form. Rather, it looks as if mixing and separating would be competing, resulting in patches of two-colored patterns formed by the wind. You can see an example of such a pattern in the attached JPG, together with a closeup (actually, an extreme crop from the original 5x7 slide) where you can distinguish the two different sorts of sand grains.
Who said that entropy always wins?