Sierra Nevada (United States)
| Sierra Nevada | ||
|---|---|---|
 Whitney as seen from Whitney Portal |
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| Highest peak | Mount Whitney ( 4421 m ) | |
| location | California , Nevada (USA) | |
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| Coordinates | 36 ° 35 ′ N , 118 ° 18 ′ W | |
| particularities | longest and highest mountain range in the USA (except Alaska) | |
The Sierra Nevada ( Spanish for "snowy mountain range") is a high mountain range in the western United States , mainly in the US state of California . The highest mountain in the Sierra Nevada, Mount Whitney , 4421 meters high , is the highest peak in the continental part of the USA , outside of Alaska .
geography
The Sierra Nevada is one of the three mountain ranges that run parallel to the Pacific coast from north to south in the western United States. The 650 km long mountain range extends from Fredonyer Pass in the north to the Tehachapi Mountains in the south. The mountain range is predominantly in the area of the US state California, only a small part, the Carson Range east of Lake Tahoe , is in the area of the state Nevada .
The mountain range forms the southern continuation of the Cascade Range and belongs to the North American Cordilleras . The Sierra Nevada is separated from the eastern Rocky Mountains by the Great Basin , and between the Sierra Nevada and the Californian coastal mountains runs the long Californian valley , which is only about 30 m above sea level .
In contrast to the Cascade Mountains, which are divided into several mountain ranges and have striking volcanic peaks, the Sierra Nevada forms a single mountain range. With a length of 640 km and a width of 80 to 130 km, it is considered the longest and highest mountain range in the USA. The mountains rise gently from the west, while in the east they descend along the eastern border of California with one of the steepest rock breaks in the world to the Great Basin.
In the north the Sierra Nevada is over 2700 m high, the middle part reaches a height of almost 4000 m and its highest point is Mount Whitney in the southern part. The high mountain zone above 2500 m is known as the High Sierra and extends over 300 km long and about 30 km wide from Pyramid Peak on Lake Tahoe to Cottonwood Pass . Around Mount Whitney there are 12 other peaks with a height of over 4200 m, some of which rise steeply three kilometers high above the Great Basin in the east. South of Mount Whitney, the mountains quickly lower and at Lake Isabella only reach an altitude of 3000 m.
Important peaks
- Mount Whitney , 4421 m
- Mount Williamson , 4390 m
- North palisade , 4341 m
- Mount Muir , 4272 m
- Mount Humphreys , 4265 m
- Mount Keith , 4262 m
- Red Slate Mountain , 4013 m
- Mount Ritter , 4010 m
- Mount Lyell , 3999 m
- Mount Dana , 3981 m
- Cathedral Peak , 3326 m
- Half Dome , 2693 m
- El Capitan , 2307 m
geology
Until about 130 million years ago, the area of today's Sierra Nevada was covered by the sea. The formation of the Sierra Nevada began in the Triassic . During this time, as a result of the continental drift, an arch of the island collided with the West American coast and set in motion mountain formation, with the formation of metamorphic rocks , which today form the essential part of the Sierra Nevada. When the Pacific clashes with the North American Plate during the Mesozoic Era about 250 million years ago, molten rock masses penetrated far into the upper layers of marine sediments and solidified as batholiths to granite . The batholith began to rise about 80 million years ago. The sea sediments deposited on the granite rock were partially removed and deposited in valleys. The gold contained in the sediments formed the basis for the 1849 gold rush . The rise of the batholith was greatest in the east. The large demolition on the eastern edge of the Sierra Nevada forms one of the most impressive geomorphological phenomena in the world, a wall over three kilometers high, which was created in a block, primarily through uplift along a trench in the earth's crust. In its present form, the Sierra Nevada is a young mountain range, about 25 to 2 million years ago it was raised in the Tertiary .
The mountain range got its current shape through weathering and erosion . Rivers flowing westwards carved deep valleys into the rock. During the Pleistocene there were at least three ice ages in the Sierra Nevada, between which there were longer warm periods. In contrast to the glaciation that covered large parts of North America, the glaciation of the Sierra Nevada was inconsistent. Some areas were not at all, in the northern part only the higher peaks were glaciated. The area south of the Donner Pass up to the upper Kern River was covered by numerous glaciers extending to the east and west. The glaciers tore rock from the mountain flanks and shaped the V-shaped river valleys into U-shaped trough valleys . Streams that poured onto ice during glaciation tumble down into the valley as waterfalls after the glaciers recede. This is how the Yosemite Valley and the San Joaquin , Kings , Kaweah, and Kern River valleys were formed. When the last ice age ended about 10,000 years ago, the glaciers had melted, leaving terminal moraines and thousands of mountain lakes behind. The largest lakes in the Sierra Nevada area are Lake Tahoe and Mono Lake . The approximately 60 glaciers that cover the peaks of Mount Lyell, the Palisades and other mountains of the High Sierra are not remnants of the Ice Age glaciers, but rather up to two kilometers long hanging glaciers that formed during a cooler epoch about 4000 years ago.
climate
The Sierra Nevada acts as a huge weather divide that removes almost all moisture from the westerly winds coming from the Pacific. The climate of the mountain range itself varies from a hot desert climate at the eastern foot of the mountains to an arctic-alpine climate on the peaks.
Due to the high pressure areas off the coast, the west side of the mountain range up to 2100 m altitude is determined by a maritime climate with cool to warm summers and warm and humid winters. The maritime influence decreases with increasing distance from the ocean. Most of the precipitation falls between October and April, but the ridge is often hit by thunderstorms in summer. Rainfall ranges from less than 250 mm annually on the South Fork of the Kern River to over 2000 mm in the mountains around the North Fork of the Feather River. The amount of precipitation decreases from north to south. Although the main ridge in the south is more than twice as high as in the north, rainfall in the south is only half that in the north of the mountain range. On the west side, most of the precipitation falls as snow in the higher elevations above 1500 m, and as rain in the lower elevations. In the lowest elevations, on the foothills of the California Long Valley, snow is extremely rare and cannot fall for decades. As the altitude increases, so does the amount and frequency. Precipitation is somewhat reduced in the highest altitudes, because they are above the maximum height of the humid air masses coming from the Pacific. The Sierra Nevada is one of the regions with the highest snowfall worldwide. On January 4, 1982, 1.7 m of fresh snow fell at the Echo Summit , the second highest amount ever recorded in the USA. In 1982, 4.7 m of snow fell in a snow storm at Donner Pass, also the second highest height ever measured in the USA. In January 1991, Tamarack had 9.90 m of fresh snow within one month, and over 22 m in the winter of 1906/07.
The summer temperature mean is between 5.5 and 15.5 ° C. Boreal climate with averages in the coldest month below −2 ° C and heavy snowfall dominates the high altitudes of the Sierra Nevada. At the tree line at 3000 m, spring, summer and autumn fall from mid-July to mid-September, but there can be frost every night at this altitude.
The regions on the east side, which are separated from the ocean by the mountain range, experience a more continental climate with warm summers, cold winters, greater daily and seasonal temperature fluctuations and lower humidity. In winter, precipitation falls mostly as snow from an altitude of 1200 m, but only in small amounts.
The Sierra Nevada is California's main water supplier. The winter snowfall is the source for the water supply of the California longest valley and the Owen Valley and thus for over 3/4 of the California population and almost all agriculture. The winter of 2013/14 had brought only 7% of the usual rainfall in the Sierra until mid-January 2014, so that Governor Jerry Brown declared a water emergency. In agriculture, a switch to water-saving crops is expected, which will lead to supply problems and price increases. (see drought in California since 2011 )
On April 1, 2015, the Sierra Nevada had a snowpack that contained only 5% of the amount of water as on average from 1951 to 2000.
Flora Fauna
At least 1,300 species of vascular plants are known for the Sierra Nevada , as well as numerous mosses and lichens . There are also at least 450 vertebrate species .
Western vegetation levels
The precipitation-rich west side of the Sierra Nevada can be divided into several successive vegetation levels:
- The mountain foothills range from about 60 to about 1000 m altitude, where they merge into mountain forests. The hilly area, criss-crossed by gullies, has a Mediterranean climate with warm, dry summers and cool, rainy winters. Today's vegetation consists of grassland, including bristles , wild oats and snail clover . The original prairie vegetation, including bluegrass , was destroyed in the 19th century by slash and burn and intensive grazing by cattle and sheep and is only preserved or restored in remnants, such as in the 634 hectare protected area of the Jepson prairie . The higher, north-facing and therefore more humid mountain slopes are often covered with forests of Californian white pines , as well as blue oaks and Californian white oaks . The sunnier and therefore drier slopes are covered with chaparral .
- The mountain forests of the lower layers begin at around 750 to 1000 m and reach a height of around 1800 m. In this zone, temperate summers and mild winters prevail, the dominant tree in this zone is the yellow pine , which in favorable locations can reach diameters of up to 2.50 m and heights of over 60 m. Other trees that are common in the dense forests are California black oak , incense cedar , sugar pines and Colorado firs . The forest zone is characterized by deep canyons in which Douglas firs , California laurel , Quercus chrysolepis and the California nut grape grow.
- The forests of the western slopes of the Sierra Nevada are the only natural habitat of the giant sequoia in the world , which grows there in groves at altitudes between 1,350 and 2,500 m. There are still about 70 of these giant sequoia groves on an approximately 420 km long and 20 km wide strip on the western slope of the Sierra Nevada.
General Sherman Tree , a giant sequoia tree in Sequoia National Park - From an altitude of 1800 m the forest changes into a forest of magnificent firs and coastal pines . In the northern Sierra Nevada, the peaks are often still covered with a stock of magnificent fir trees that grow to an altitude of 2700 meters. The dense, magnificent fir forests are much more shady and therefore cooler than their surroundings and thus create a different microclimate . Coast pines and western Weymouth pines grow less frequently in these forests . The undergrowth consists of sacred flowers ( Ceanothus ), Chrysolepis and bearberries .
- In the subalpine zone above 2700 m up to the tree line, mountain hemlocks , magnificent firs, coastal pines and western Weymouth pines still grow . The West American juniper also grows adapted to the granite rock . The white-stemmed pine grows up to an altitude of 3300 m on southern slopes .
- Only a few alpine plants grow in the stony desert of the alpine zone above 3000 m. The white-stemmed pine reaches a height of 50 cm up to a height of 3650 m. On the east side, stunted specimens of mountain hemlocks and coastal pines grow up to around 3400 m. The foxtail pine grows in isolated locations near the tree line in the southern Sierra Nevada .
Eastern vegetation levels
The eastern slopes of the Sierra Nevada in the rain shadow merge into the desert of the Great Basin. The upper vegetation levels in the east of the Sierra Nevada correspond to those on the west side, but are shifted to a higher altitude and are much more compact and less pronounced due to the steep slope of the east side of the Sierra Nevada. From the alpine zone to the semi-desert there are only a little more than three kilometers as the crow flies.
- At the tree line there is still a mountain forest of coastal pines and white-stemmed pines. The mountain forest of the lower elevations consists of flexible pines and Berghemlock firs, in the drier regions it is composed of Jeffrey pines and magnificent firs . Along the streams growing Populus tremuloides , in drier growing layers Sagebrush up to an altitude of 3000 m. The foothills of the Sierra Nevada in the east are dominated by the single-leaved pine , followed by Utah juniper and Pinus edulis , before the coniferous forest finally merges into the dry vegetation of the Great Basin.
fauna
The dense mountain forests of the Sierra Nevada are home to numerous smaller mammals such as chipmunks , gold-coated ground squirrels , Sierra pocket rats , stubby squirrels and Ursons . Their hunters are ermines , long-tailed weasels , spruce marten and, much less often, fisher marten . Larger mammals include mule deer , pumas , bobcats, and black bears . Bighorn sheep , pigeon rabbits , Belding ground squirrels and yellow-bellied marmots can be found in the Alpine zone . The many bird species include the great gray owl , great horned owl , pine jay , rock mountain fowl and mountain quail . Ptychocheilus grandis , Mylopharodon conocephalus , white fish , Cottus gulosus , Catostomus occidentalis and rainbow trout live in the lakes, rivers and streams .
history
The Sierra Nevada got its name from the Spanish de Anza expedition , which explored California in 1776. The Franciscan Pedro Font was born during the expedition of a hill near the San Francisco Bay behind a vast, treeless plain, a mighty, snow-capped mountain range that ran from south-southeast to north-northwest. In his diary and on a sketch map he noted the name Sierra Nevada .
The first white man to cross the Sierra Nevada is Jedediah Smith , who, together with two companions, crossed it from west to east over the Ebbetts Pass in May 1827 . Between 1843 and 1844 John Charles Frémont explored essential parts of the mountain. The California gold rush brought thousands of prospectors to the Sierra Nevada. The California Trail over the 2162 m high Donner Pass was used by thousands of gold prospectors and immigrants in the 19th century. In 1863 construction began on the Central Pacific Route railway line that crossed the Sierra Nevada via Donner Pass. Later another railway line was built through the Sierra Nevada with the Feather River Route over the Beckwourth Pass .
The prospectors had cut down or burned down numerous forests to look for gold and to extract timber. The deforested or burned areas subsequently served as pasture for huge herds of sheep and cattle. At the same time, intensive timber management was carried out in large parts of the Sierra Nevada until several laws regulated the use of agriculture and forestry from 1890 or the areas were placed under nature protection. The most important nature conservation activist for the Sierra Nevada was John Muir from Scotland, who explored the mountains from 1868 until his death in 1914 and made them known worldwide with his descriptions. From a scientist to a pioneer of nature conservation, Muir founded the Sierra Club in 1892 and successfully campaigned for the establishment of national parks. The first sanctuary to be established was the Mariposa Grove in 1864 , which became part of Yosemite National Park , founded in 1890 in 1906 . In the 1890s the Sequoia and General Grant Grove National Park were established . The General Grant Grove went up in 1940 in Kings Canyon National Park .
Environment and nature protection
One of the current threats to the Sierra Nevada mountains is air pollution in California, especially in the San Joaquin Valley , which is leading to the death of young pines and giant sequoias. The rivers that flowed westward from the Sierra Nevada into California's long valley often caused severe flooding during the snowmelt. Many rivers have been dammed for flood protection and are now used for irrigation and water supply for industry and households in the summer months. As a result, less and less water flows directly into the sea via the rivers, but is used at least once before it flows into the sea or into the groundwater.
Protected areas
In the Sierra Nevada area there are three national parks, Yosemite National Park, Kings Canyon and Sequoia National Park, Devil's Postpile, a national monument, nine national forests and numerous state parks . The high mountains of the southern Sierra Nevada are protected by 20 contiguous wilderness areas such as the Ansel Adams Wilderness and the John Muir Wilderness .
tourism
The national parks, especially Yosemite National Park, are very popular excursion destinations in summer. The Pacific Crest Trail and the John Muir Trail are long-distance hiking trails through the mountains. The best known of the numerous winter sports areas of the Sierra Nevada because of the abundance of snow is Squaw Valley .
literature
- Verna J. Johnston: Sierra Nevada: The Naturalist's Companion. University of California Pr., Berkeley, 1998. ISBN 0-520-20936-2
- Bill Guyton (of the University of California): Glaciers of California ; University of California Press (October 27, 1998); ISBN 978-0-520-21295-4
- John Mock and Kimberley O'Neil: Hiking in the Sierra Nevada (Lonely Planet Hiking in the Sierra Nevada) ; Lonely Planet Publications (June 2002); ISBN 978-1-74059-272-7
- Allan A. Schoenherr: A Natural History of California ; University of California Press (1992); ISBN 0-520-06922-6
- TI Storer, RL Usinger and D. Lukas: Sierra Nevada History ; University of California Press (2004); ISBN 0-520-24096-0
- NL Weeden: A Sierra Nevada Flora ; Wilderness Press (1996); ISBN 0-89997-204-7
Individual evidence
- ^ The Geology of The Sierra Nevada. (No longer available online.) Archived from the original on August 17, 2010 ; Retrieved October 28, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ Nationalatlas.gov: Sierra Nevada. (No longer available online.) Archived from the original on October 8, 2012 ; Retrieved October 28, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Sierra Nevada Photos: Winter Snow Depth. (No longer available online.) Archived from the original on February 15, 2012 ; Retrieved October 24, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ Sacramento Bee: Jerry Brown declares California drought emergency, urges 20 percent cut in water use , January 17, 2014
- ^ The Wire: After Its Driest Year Ever, California Desperately Needs the East Coast's Snow , Jan. 21, 2014
- ↑ http://science.orf.at/stories/1762870/ Drought: Hardly any more snow in the Sierra Nevada, science.orf.at, September 14, 2015, accessed September 14, 2015.
- ^ UC Davis Natural Reserve System - Jepson Prairie Reserve. Retrieved October 24, 2012 .
- ^ Verna J. Johnston: Sierra Nevada: The Naturalist's Companion, p. 58
- ^ Climate of California. Retrieved October 27, 2012 .
