The Huachucas are one of nearly forty mountain ranges in the borderland region called “sky islands,” for they stand like islands surrounded by a desert “sea.” This series of mountains, arranged like stepping stones across the land, is often termed an “archipelago.” Nurtured by a temperate to subtropical climate, the sky islands exhibit exceptional biological wealth. The Sierra Madre and associated ranges of southeast Arizona have been identified as one of three centers of megadiversity on our planet.

The memorial contains 4,750 acres with elevations ranging from 7,825 feet to 4,825 feet protects the Montezuma Canyon watershed, which drains most of the memorial into the San Pedro River to the east. Very steep mountain side slopes and nearly vertical cliffs and escarpments are typical of the northwestern portion of the memorial. The northern portion of the Memorial consists of a prominent ridge that generally trends west to east. Inside the park, this ridge is dissected with numerous canyons draining to the south and southeast into Montezuma Canyon.

The southeastern part of the memorial is a broad, gently sloping fan terrace dissected by numerous drainageways. Riparian zones are most distinctive in the main drainages, but what little permanent or semi-permanent water there is occurs in a few isolated seeps and steel cattle tanks.