San Bernardino Mountains

San Bernardino Mountains
The San Bernardinos seen from near Sugarloaf Mountain
Highest point
Peak	San Gorgonio Mountain
Elevation	11,503 ft (3,506 m)[1]
Coordinates	34°05′57″N 116°49′29″W / 34.09917°N 116.82472°W / 34.09917; -116.82472
Dimensions
Length	60 mi (97 km)
Width	41 mi (66 km)
Area	2,063 sq mi (5,340 km2)[2]
Geography
Country	United States
State	California
Counties	San Bernardino and Riverside
Settlements	San Bernardino, Crestline, Lake Arrowhead, Running Springs and Big Bear Lake
Range coordinates	34°12′N 117°00′W / 34.2°N 117°W / 34.2; -117
Parent range	Transverse Ranges
Borders on	San Gabriel Mountains, San Jacinto Mountains and Little San Bernardino Mountains
Geology
Age of rock	Miocene and Quaternary
Type of rock	Fault-block and sedimentary

The San Bernardino Mountains are a high and rugged mountain range in Southern California in the United States.^[3] Situated north and northeast of San Bernardino and spanning two California counties, the range tops out at 11,503 feet (3,506 m) at San Gorgonio Mountain – the tallest peak in Southern California.^[4] The San Bernardinos form a significant region of wilderness and are popular for hiking and skiing.

The mountains were formed about eleven million years ago by tectonic activity along the San Andreas Fault, and are still actively rising. Many local rivers originate in the range, which receives significantly more precipitation than the surrounding desert. The range's unique and varying environment allows it to maintain some of the greatest biodiversity in the state.^[5] For over 10,000 years, the San Bernardinos and their surroundings have been inhabited by indigenous peoples, who used the mountains as a summer hunting ground.^[6]

Spanish explorers first encountered the San Bernardinos in the late 18th century, naming the eponymous San Bernardino Valley at its base. European settlement of the region progressed slowly until 1860, when the mountains became the focus of the largest gold rush ever to occur in Southern California. Waves of settlers brought in by the gold rush populated the lowlands around the San Bernardinos, and began to tap the mountains' rich timber and water resources on a large scale by the late 19th century.

Recreational development of the range began in the early 20th century, when mountain resorts were built around new irrigation reservoirs. Since then, the mountains have been extensively engineered for transportation and water supply purposes. Four major state highways and the California Aqueduct traverse the mountains today; these developments have all had significant impacts on area wildlife and plant communities.