San Bernardino Mountains - Geography

Geography

The San Bernardinos run for approximately 60 miles (97 km) from Cajon Pass in the northwest – which separates them from the San Gabriel Mountains – to San Gorgonio Pass, across which lie the San Jacinto Mountains, in the southeast. The Morongo Valley in the southeast divides the range from the Little San Bernardino Mountains. Encompassing roughly 2,100 square miles (5,400 km2), the mountains lie mostly in San Bernardino County, with a small southern portion reaching into Riverside County. The range divides three major physiographic regions: the highly urbanized Inland Empire to the southwest, the Coachella Valley in the southeast, and the Mojave Desert to the north. Most of the range lies within the boundaries of the San Bernardino National Forest.

From its northwestern end, the crest of the mountains rises steadily until they are interrupted by the gorge of Bear Creek. The northern part of the San Bernardinos is a large upland plateau characterized by a series of extensive subalpine basins, including Big Bear Valley, and is home to several large water supply reservoirs. South of the Big Bear area the range is cut by the Santa Ana Canyon, the broad valley of the Santa Ana River, and rises dramatically to culminate at Mount San Gorgonio and eleven other peaks that exceed 10,000 feet (3,000 m) in elevation. The mountains feature a steep drop into the Coachella Valley and San Gorgonio Pass – the latter of which is one of the deepest mountain passes in the United States, exceeding the Grand Canyon's depth by over 2,000 feet (610 m).

Many cities lie at the base of the San Bernardino Mountains. These include San Bernardino, Redlands and Yucaipa in the south; Yucca Valley to the east; and Hesperia to the northwest. In addition, there are several mid-sized to large towns in the mountains themselves, including Big Bear City, Crestline, Lake Arrowhead and Running Springs. Cities within the San Bernardino Mountains total a population of about 44,000, with this number sometimes increasing tenfold during peak tourist season. Several regional streams and rivers also have their headwaters in the mountains. The principal drainage is provided by the Santa Ana River, which runs westwards into the Pacific Ocean in Orange County. Other streams flowing off the mountains include the Whitewater River, flowing southeast through the Coachella Valley into the Salton Sea, and the Mojave River, which drains northwards into the Mojave Desert.