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The San Bernardino Mountains are a high and rugged mountain range in Southern California in the United States. Situated north and northeast of San Bernardino and spanning two California counties, the range tops out at at San Gorgonio Mountain – the tallest peak in all of 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 surrounds 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. 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. 207〕〔Holtzclaw, 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 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 40 inches (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 March; summers are mostly dry except for infrequent thunderstorms during late summer. During the colder winter storms, snow can fall above 3,000 feet, but most usually falls above 5,000 feet. Ski resorts (mostly in the Big Bear area) capitalize on this snowfall, the most reliable south of the Sierra Nevada Mountains. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「San Bernardino Mountains」の詳細全文を読む スポンサード リンク
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