legend of native americans indians

Valeur exceptionnelle

Le Parc national de Yosemite illustre de façon très vivante les effets de l’érosion glaciaire de substrats granitiques, créant des caractéristiques géologiques uniques au monde. Des glaciations répétées pendant des milliers d’années ont abouti à une concentration de caractéristiques paysagères particulières, dont des falaises escarpées, des dômes et des chutes d’eau vertigineuses. La topographie glaciaire est exceptionnelle, notamment la spectaculaire Vallée de Yosemite, encaissement glaciaire de 914 mètres (1/2 mile) de profondeur aux parois de granit pur. Ces caractéristiques géologiques offrent un cadre panoramique aux prairies de montage et aux bosquets de séquoias géants, créant un paysage diversifié d’une beauté naturelle et panoramique exceptionnelle.

Critères

(vii) Yosemite est d’une beauté naturelle exceptionnelle et abrite 5 des plus hautes chutes d’eau du monde, un ensemble de dômes et de murs de granit, des vallées profondément encaissées, trois bosquets de séquoias géants, de nombreuses prairies alpines, des lacs, des zones biologiques très diverses et une grande variété d’espèces.

(viii) L’action glaciaire associée aux substrats granitiques a produit des caractéristiques géologiques marquées, en particulier des structures en dôme poli, vallées suspendues, petits lacs de montagne, moraines et vallées en U. Les reliefs granitiques comme Half Dome et les parois verticales d’El Capitan sont des illustrations caractéristiques classiques de l’histoire géologique. Aucun autre lieu ne présente les effets de la glaciation sur les substrats granitiques en dôme aussi bien que Yosemite.

Yosemite National Park, on the west slope of the central Sierra Nevada Mountains, is an area of outstanding scenic beauty and great wilderness value. The park represents practically all the different environments found within the Sierra Nevada, including sequoia groves, historic resources, evidence of Indian habitation, and domes, valleys, polished granites and other geological features illustrating the formation of the mountain range.

The park is dominated by the Sierra Nevada, which is a tilted granite area. Granite underlies most of the park and is exposed as domes, partial domes, knobs and cliffs. There is exceptionally glaciated topography over most of the area including the spectacular Yosemite Valley, a 914 m deep cleft carved by glaciers through a gently rolling upland. The valley is a widened portion of the prevailing narrow Merced River canyon which traverses the southern sector of the park from east to west. The massive sheer granite walls present a freshly glaciated appearance with little postglacial erosion. The park is known for its many waterfalls, including the Yosemite Falls and Ribbon Falls, and some 300 lakes, including Emerald and Merced. Other notable canyons in the park are the Grand Canyon of the Tuolumne River and the Tenaya Canyon. There are also two major rivers (Merced and Tuolumne). The area was previously heavily glaciated and, although no glaciers are still existent in the park, the marks of their passing are everywhere. Glacial action combined with the granitic bedrock has resulted in unique and pronounced landform features. These include distinctive polished dome structures as well as the related glacial features of hanging valleys, tarns, moraines and U-shaped valleys. Monolithic granitic blocks such as Half Dome and the perpendicular wall of El Capitan are classic distinctive reflections of the geological history of the area.

The variety of flora is reflected in the existence of six distinct vegetation zones which are governed by altitudinal variation. Notable are three groves of the giant sequoia tree and extensive alpine meadows. There are 1,200 species of flowering plant along with various other ferns, bryophytes and lichens. There is one endemic and eight threatened or endangered species of plant.

The park has 67 mammalian species, of which 32 are rodents, 221 species of bird, 18 reptile, 10 amphibian and 11 fish, of which 6 are endemic. One bird species (bald eagle) is endangered and the peregrine falcon is listed as vulnerable. A few non-native species have been accidentally introduced such as beaver and white-tailed ptarmigan. Bighorn sheep were declared extinct in Yosemite in 1914 but were reintroduced in 1986.

There are 1,000 designated archaeological sites recorded by visitors, park staff and during systematic archaeological surveys. Yosemite is viewed as a boundary zone between the two major cultural provinces of Central California and the Great Basin. In late prehistoric and historic times Yosemite was occupied by two main tribes of North American Indians. There are 569 designated archaeological sites within the park.

Yosemite's natural beauty was the impetus, then, for the first implementation of the national park concept as we know it today. Adding to Yosemite's cultural importance are the archaeological features found in the area.

Much change has however occurred in the Yosemite landscape. Suppression of natural fires and heavy stock and sheep grazing in the past has also altered the original vegetation.

Act of Congress of 30 June 1864 (13 Stat. 325) granted Yosemite Valley and Mariposa Big Tree Grove to the state of California (regranted to the US government in 1906). Establishment of Yosemite National Park as a forest reservation on 1 October 1890 (26 Stat. 650) excluding Yosemite Valley and Mariposa Grove. Boundary adjustments were made in 1905. Park extension in 1929 of 4,846.47ha and further extensions in 1930, 1931, 1932, 1937, 1938 and 1984. Designated as a World Heritage site in 1984.