The mountain ranges that make up southeastern Arizona’s Sky Islands are high enough and cover enough area to support forests at their higher elevations. Each forested mountaintop is an island unto itself, separated from the others by the surrounding “sea” of desert. The highest of all the Sky Island ranges is the Pinaleños. These mountains have 7,000 feet of vertical relief and are the only Sky Island range that reaches elevations over 10,000 feet. The high point is the summit of Mount Graham at 10,720 feet. The high life, indeed.
A small arroyo behind my house leads eventually to Mescal Wash and, from there, through ever widening washes until eventually reaching the Santa Cruz River, about forty miles to the west. Also near my house, there is this low ridge just a few hundred yards to the east. On the other side of its low crest is an arroyo called Cornfield Wash, and it leads a scant few miles to the nearby San Pedro River. That means that this modest ridge line marks a divide between two major river valleys in southern Arizona; the San Pedro drainage to the east, and the Santa Cruz to the west.