It is delimited by Arizona State Route 86, from east-to-west on the north separating it from the Avra Valley which then trends northwesterly, merging into the plains and drainage of the Santa Cruz River.

The ranges were broken up by Basin and Range faulting, and leaving wide areas of bajadas or graben-type valleys, sometimes with obvious horst-type mountain ranges; even extreme volcanic cones can form on these horst boundaries, like the seven minor volcanoes at the northern end of the Mohawk Mountains The Buenos Aires National Wildlife Refuge borders the southeast Altar Valley and covers half the valley's length.

The lower elevation Cerro Colorado range borders the refuge to the northeast, the similar San Luis Mountains to the southeast.

These two areas of southwest Arizona and northwest Sorona are most inhospitable and dangerous in summer months.

(The Barry M. Goldwater Air Force Range uses the Arizona region because of its remoteness and yeartime usage abilities by flight.)