Roadside Geology of Arizona

The rise of mountains and the spread of deserts has marked the geologic history of Arizona. Landscapes of the past, and because of tremendous forces deep within the earth, forces that carry continents into collisions and then drag them apartagain, forces of heat and pressure and the slow churning boil of the earth's interior. Landscape features result, too, from more comprehensive, more recent forces: the unending attack of water and wind and frost, the building of volcanoes, the short-term geologic happenings like landslides and rockfalls, earthquakes and floods, and a gopher digging a hole....