Calico Cliffs, right??
Red rocks are hard and I have the bad paintings to prove it! Over time I've learned that you need to avoid curves in the rocks or they end up looking like potatoes. Or at least mine did. Also, I think your highlights are a bit too white, unless you're going for snow. You've caught the colors of that formation beautifully- if I were painting it I think I'd mute the blues in the crevices just a tad.
Hope you enjoyed Red Rocks! Looks like you did, even w the spotty weather that day. Most people who visit Vegas have no idea that place exists!
Oh and one other thought. I was struggling w a work from a trip to Zion w a somewhat similar rock wall. It was not working and I ended up wiping it off - the result was exactly what I was looking for! http://www.wetcanvas.com/forums/show....php?t=1102262
The painting is totally different from what you're going for here, but you might find the rocks interesting. Call me the accidental artist.