This is an area of Navajo sandstone that sort of defies conventional wisdom. The color in sandstone is supposedly deposited by water carrying oxides through the rock after the original sand dunes have been turned to stone. With the well-defined colors associated with specific layers of stone, though, one would think that the colored oxides were actually laid down with the blowing sand and were already present as the rock formed. But from what I read, that's not the case. The color comes later, well after the lithification process. While it's maybe difficult to imagine what happened in the genesis of this particular formation, there's little doubt that it's quite unique.