Aerial View Maps

What is this white stuff on aerial photography of fields?

Looking at Google maps I see all this white stuff on fields in South Dakota. At first I thought it was a winter photograph and that it was snow, but looking at some other photography (from July) I see that it's still there. Below is an example. Any thoughts? http://maps.google.com/?ie=UTF8&ll=45.376478,-103.417804&spn=0.009888,0.022724&t=k&z=16

Public Comments

1. rocky area, Dirt i thinks its just rocky formations on the ground, like a change in terrain. or a dirt covered patch of land...
2. ROCKS
3. its the badlands in South Dakota. just the color of the rock here is a pic http://en.wikipedia.org/wiki/File:HellsHalfAcre.JPG
4. It might be agricultural lime. They spread crushed limestone to neutralize pH.