A Landscape Built by Fire — a stop on the Coronado Trail Scenic Byway.
The mountains around you are volcanoes — worn down, extinct, and much bigger than they look.
This is the edge of the White Mountains volcanic field, and it was seriously active from a few million years ago until, geologically speaking, quite recently. Escudilla, which we passed, is a shield volcano. Much of the rock you'll see in the roadcuts today is basalt — dark, fine-grained lava — and in places you can pick out individual flows stacked on each other like layers in a cake, each one a separate eruption with soil formed in between.
Further south, as we drop, the rock changes completely and gets much older and much stranger: rhyolite and volcanic tuff from enormous explosive eruptions, then, right at the bottom around Clifton and Morenci, ancient rock shot through with mineral-rich fluids — which is precisely why there is one of the world's largest copper mines down there. The geology and the economy are the same story.
Watch the roadcuts. On a road with this many curves, you get an unusually good cross-section of what's under Arizona, sliced open every few hundred yards. Look for the columns — basalt cools into hexagonal columns, and there are some beautiful examples along here.