The San Bernardino Mountains are a high and rugged mountain range in Southern California in the United States. The mountain range is part of the Transverse Ranges and lies north and northeast of San Bernardino and spanning two California counties, the range tops out at at San Gorgonio Mountain – the tallest peak in Southern California.Lancaster, p. 6 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.Grinnell, pp. 1–2 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.
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.
Geography and climate The San Bernardinos run for approximately 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 , 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.
Highest peaks of the San Bernardino MountainsPeakElevationftmSan Gorgonio MountainJepson PeakBig Draw PeakBighorn MountainDragons HeadAnderson PeakCharlton PeakSan Bernardino East PeakShields PeakSan Bernardino PeakAlto Diablo
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 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 .Hall, p. 207Holtzclaw, p. 7
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 Lake, 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.Robinson and Harris, p. 1 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.
The San Bernardino Mountains (along with the adjacent San Gabriel and San Jacinto Mountains) are a humid island in the mostly semi-arid southern California coastal plain. Parts of the San Bernardino Mountains have annual precipitation totals in excess of (e.g. Lake Arrowhead and Barton Flats areas), and provide an important water resource for the coastal plain below. Most of the precipitation falls between November and April; summers are mostly dry except for infrequent thunderstorms during late summer. During the colder winter storms, snow can fall below , but most usually falls above . Ski resorts (mostly in the Big Bear area) capitalize on this snowfall, the most reliable in California south of the Sierra Nevada Mountains.
Geology
The San Bernardinos are part of the Transverse Ranges of Southern California, a mountain chain formed by tectonic forces between the North American and Pacific Plates along the San Andreas Fault. An early version of the range rose in the Miocene, between eleven and five million years ago, but has largely eroded. The range was shaped into its present form during the Pleistocene epoch beginning approximately two million years ago, with regional uplift continuing to the present. The rocks that make up the mountains are much more ancient than the mountains themselves – ranging from 18 million years to 1.7 billion years old. The San Andreas Fault was also responsible for the formation of both major mountain passes that mark the east and west ends of the range.
These mountains are shaped by several primary tectonic or fault blocks – the Big Bear block, which forms the large montane plateau that characterizes the northern portions of the range; and the more complex and fractured San Gorgonio, Wilson Creek and Yucaipa Ridge blocks, which form the rugged and heavily dissected southern parts of the mountains. Because of their large, steep rise above the surrounding terrain, the San Bernardinos have been subject to great amounts of erosion that have carved out numerous river gorges. Rocks and sediment from the mountains are deposited on the surrounding valley floors as massive alluvial fans. Regional alluvial deposits can reach depths of or more, and their permeable soils constitute several major groundwater basins.
History
Indigenous peoples Archaeological discoveries in the San Bernardino Valley suggest that humans have populated the region for at least 10,000-12,000 years. Several Native American groups held the lands surrounding the San Bernardinos. These included the Tongva, who occupied the Inland Empire area southwest of the mountains; the Cahuilla, who lived in the Coachella Valley and Salton Sea basin; and the Serrano and Chemehuevi peoples, whose territory comprised land north and northeast of the San Bernardinos, adjacent to the Mojave Desert.Gunther, pp. 161–162 Most of these tribes did not have permanent settlements in the mountains, with the possible exception of a few groups of Serrano.Robinson and Harris, p. 32
Indigenous peoples traveled into the mountains in the summer to hunt deer and rabbits, gather acorns, berries and nuts, and seek refuge from the desert heat. They established well-traveled trade routes, some of which were later used by Europeans to explore and settle the region. The precipitous Mojave Road (or Mojave Trail) crested the San Bernardinos east of Cajon Pass and permitted trade between people of the Inland Empire basin and the Mojave Desert. San Gorgonio Pass, which forms the largest natural break in the Transverse Ranges, also allowed interaction between coastal and desert tribes. River canyons, especially those of the Mojave and Santa Ana, provided the major means of entry to the mountains. Many archaeological sites have been discovered along Deep Creek, a tributary of the Mojave River, in particular.
History During the 17th and 18th centuries, various Spanish explorers passed through coastal Southern California and claimed the area for Spain. In 1769, the Spanish government began an effort to bring what they called Alta California under their control and introduce Christianity to native peoples through the construction of missions. It was not until 1772 when the military governor of Alta California, Pedro Fages, became the first European known to reach the San Bernardino Mountains. Although the original purpose of his expedition was to pursue deserters from the Spanish army, he ended up venturing into not just the San Bernardinos but also the San Jacinto Mountains, the Mojave Desert, and eventually north into the Central Valley.Hoover and Kyle, p. 321
The San Bernardinos and their surrounds were sporadically explored throughout the next 50 years or so - first by Francisco Garcés, the first known European to use the Mojave Road, in 1776, followed by José Maria de Zalvidea, who surveyed the Mojave River area in 1806.Robinson and Harris, pp. 32–33 In 1810, Francisco Dumetz led a small company to build a temporary chapel near what is now Redlands. On May 20, the Feast Day of Bernardino of Siena, Dumetz named the San Bernardino Valley. This name was applied to San Bernardino Peak by 1835, and was in wide use for the entire range by 1849.Gudde and Bright, p. 330
In 1819, San Bernardino de Sena Estancia was created near present-day San Bernardino as an outpost of nearby Mission San Gabriel Arcángel. Although sometimes referred to as an asistencia, or "a mission on a small scale with all the requisites for a mission, and with Divine Service held regularly on days of obligation, except that it lacked a resident priest", San Bernardino was an estancia, or cattle ranch.Weber, p. 50 In 1820, a irrigation ditch or "zanja" was dug using Native American labor to furnish water from Mill Creek, a major stream flowing out of the San Bernardinos, to the estancia and surrounding croplands. For the next twenty years, the Spanish – then the Californios under newly independent Mexico – practiced agriculture and ranching at the foot of the mountains.Robinson and Harris, p. 33
The high country of the mountains remained largely unexplored until 1845, when Benjamin D. Wilson led a party of 22 men from a rancho near present-day Riverside to catch several Mohave cattle rustlers who had fled into the mountains. Wilson was the first recorded European to see the Big Bear Valley, and named Bear Lake (today's Baldwin Lake) for the abundance of California grizzly in the area. The party captured and skinned more than twenty bears. Later, they found and arrested the rustlers, who were hiding along the Mojave River. Wilson's expedition opened the interior of the San Bernardinos to later exploration, and discouraged Native Americans such as the Mohave from staging similar raids over the mountains.Robinson and Harris, p. 34Storer and Tevis, p. 24