The Transition Highlands, or Central Mountains, consist of numerous rugged low mountains marking the boundary between the tablelands of the Colorado Plateau and the southern deserts of the Basin and Range physiographic zone.  In the Southwest, the Transition Highlands are dominated by the Mogollon Rim, a massive break in the earth’s topography stretching diagonally across Arizona and into New Mexico.  In places, the Rim is a sheer escarpment nearly 2,000 feet high.

Area:  33,735 sq. miles.

Precipitation:  Average 25- 51 cm (10-12 in); above 1,524 meters (5,000 ft) in elevation, much of the annual precipitation in the Transitional zone falls as snow.  On the Mogollon Rim, precipitation averages 50 cm (21 in).

Temperature:  Temperatures in the Transition Highlands are relatively moderate; summer temperatures reach the low 90s and winter temperatures drop into the mid-20s.

Elevation: The elevation of the Transition Zone averages between 1,200 – 1,500 meters (4,000 – 5,000 feet), but exceeds 2,130 meters (7,000 ft) along the Mogollon Rim.

Life Zones:  Upper Sonoran

Vegetation:  Open ponderosa pine forests dominate much of the Transition Zone, but oak woodlands, chapparal, oak-pine woodlands, and pinyon-juniper woodlands also form the vegetative regimes of the region.

Geology:  The geology of the Transition Zone includes sedimentary, igneous, and metamorphic rocks.  The geological conditions of the region have resulted in extensive deposits of copper, which is mined around Clifton and Globe. 

Prehistoric Cultures: Mogollon, Salado, Mimbres Mogollon, and Southern Sinagua.

National Parks and Monuments: Tuzigoot, Montezuma’s Castle, Tonto, and Gila Cliff Dwellings.

External links:
Mogollon Rim Executive Summary