Good stuff (again!). I grew up in Southern California and spent a large part of my summers in the desert along the Colorado River near Parker, AZ. The desert is, indeed, an alien landscape in many ways, but a very beautiful one nonetheless.

There are similar petroglyphs near Albuquerque, NM. It's amazing what a wide range the peoples of that early time had (even if they were different tribes at the time). Of course, the climate might have been much different then and not as harsh in these regions.