The Sierra Mazatán (also known as the Sierra Huerfana by locals) is at the southern edge of the Sky Island region. The range is on Sonora's coastal plain and the nearest high country to Hermosillo. It is dominated by thorn-scrub on slopes and oak woodland at higher elevations.
The Sierra Mazatán is composed of granite and is geologically one of the newest Sky Islands. It is a broad, flat-topped Sierra that tops out at around 1550 meters. Few Sky Islands can compare with the Mazatán in terms of flat, level high country. Generally the mountain is about 12 x 12 km with somewhat steep slopes with a mesa-like top that is generally between 1300 and 1500 meters.
The Mazatán barely protrudes above the thorn-scrub that dominates its flanks. If one drops into one of the range’s few large canyons, the transition from oak forest to thorns-scrub begins quickly.
The mountain is dominated by Quercus chihuahuensis as well as hosting abundant Quercus oblongifolia. Higher areas with deeper soil and more mesic conditions have nice stands of Quercus vimenea. Since these are the nicest parts of the mountain they are also where ranches are located. Apparently there are also three individual Quercus arizonica near the numerous microondas that sit on the highest peak. Quercus tuberculata is not uncommon in canyon bottoms at the transition zone between thorn-scrub and oak woodland.
Due to the relatively level nature of the mountain, there are numerous ranches and heavy cattle grazing in many areas. One primary dirt road, with a few rough sections, traverses the mountain range from northeast to southwest.
This mountain is kept alive by the summer monsoons! After summer rains begin, a barren soil surface erupts with abundant forbs while lifeless looking oaks and other plants rapidly put on new growth, forming a very green landscape.