This looks like a dry riverbed. The ground is dry and cracked, just like the rocks themselves.
It looms like an ancient city. The road to Monument Rocks was much better to drive than Castle Rock. The only problem was...there were people at this one! But they were okay.
When I saw these kids climbing down the rock, I realized how easy it would be to climb to the top. The following pictures were taken from there. If I wasn't traveling alone, I might have pictures of me on the rock, but there are none.
Across the road there's another small city of these sandy walls.
People had carved names and dates into the stone on top of the wall. I didn't bother taking any pictures of those though.