National park of Yosemite

The national park of Yosemite is located in the mountains of the Sierra Nevada, in the east of the California, the the United States. With an total surface area of 3079 km2, it is the third larger park of California. Classified National park in 1890, Yosemite is the older second of the American history, after that of the Yellowstone. More than 2,5 million tourists attend it each year, which in fact, with the Large Canyon of Colorado, one of the most visited natural sites country. Its falls of water and its spectacular granitic dome S attracts each year of the thousands of climbing hikers and coming from the whole world. Yosemite is a park of high mountain whose natural and landscape diversity was recognized world heritage of Humanity by UNESCO in 1984. But the intense tourist frequentation, in spring and in summer, poses environmental problems in the Vallée of Yosemite.

Geographical situation and characteristics

The national park of Yosemite is in the center of the Sierra Nevada, the highest assembly line of California. It is with horse on the Comté of Mariposa and the Comté of Tuolumne. Approximately 3:30 is needed conveys some to come from San Francisco and 6 hours since Los Angeles. The national park is surrounded by several natural reserves: Ansel Adams Wilderness in south-east, Hoover Wilderness in the North-East northeast and Emigrating Wilderness in north.

The surface of Yosemite is of 3079 km2, of which 94 % are classified; but the tourists do not visit that 36 km2 are 1 % of the park, primarily in the valley of Yosemite, traversed by the river Merced, to 1200 m of altitude.

Relief

The culminating point is the Mont Lyell (3997 m), in the south-east of the park. Several tops exceed the 3500 meters of altitude and all are located at the east: the Mount Clark (3780 m), Small Peak (3539 m) and Price Peak (3515 m). Indeed, the Nevada Sierra is an asymmetrical chain with a Western slope which go up gradually towards the watershed, and an Eastern slope which goes down in an abrupt way. The park of Yosemite is in the first part.

With more large scales, erosion works the granite of Yosemite in vigorous forms: domes, peaks, columns, etc the forces of this erosion are water, the differences in temperature (Thermoclastie) and the chemical decomposition. The park is famous for its domes whose granite splits up in layers: North Dome, Half Dome, Liberty Cape, Pywiack Dome, etc

Hydrography

More than 2500 km of and hundred river of lakes of glacial origin are within the limits of the park of Yosemite. This last is crossed by two important rivers, which run of is in west and which are affluents of the San Joaquin: the Merced To rivet in the Valley of Yosemite, and the Tuolumne To rivet, in the north of the park. They run towards the Central Vallée of California while crossing the Piedmont of the Nevada Sierra. Many rivers are thrown in these two rivers, sometimes in the forms of water falls.

Merced River sprinkles a basin of (1320 km2). At the end of the month of April 2006, its depth was of 2.7 m with Pohono; it can overflow and cause floods: most important were those of 1937,1950,1955 and 1997.

There exist two lakes of reserve in the North-West of the park: Hetch Hetchy Reservoir, which provides water to the agglomeration san-franciscaine and the Lake Eleanor. Today, of many glacial lakes were filled by the Sédiment S and become meadows Marécage use called “ meadows ” in English); formerly, the Valley of Yosemite contained a lake.

Climate

The national park of Yosemite knows a mountain Climat and is subject to the influence of the masses of air coming from the Pacific Ocean, located at less than 200 km as the crow flies. The temperatures decrease with altitude:

Tuolumne Meadows (2627 meters): -3,9 with 11,5°C
Valley of Yosemite (1220 meters): -3 with 32°C
Wanona Fan-in (1887 meters): 2,2 with 19,4°C

Beyond 2500 meters, in summer, dry heats are moderated by thundery showers. The combination of a dry vegetation, low level of moisture and storms causes frequent forest fires.

The valley of Yosemite (Yosemite Valley) is at an altitude of approximately 1200 m and is not covered any more with snow in spring. But with Tuolumne Meadows (2627 m), snow still covers the ground at the end of spring. At the end of the month of April 2006, one could measure 1.8 more m of snow there. The landscape of the park is dominated by gigantic blocks of granite. Several million years ago, this rock was formed in-depth by very slow cooling of the Magma, component of vast magmatic intrusions called Batholite S. the magma has also affected the sedimentary rocks and volcanic close: today, one meets these metamorphic rocks in periphery of the park, in restricted sectors, in particular with the Dana Mount.

Geological history of Yosemite

Formation of the sedimentary rocks and an insular arc

The oldest phase takes place during the Précambrien and the beginning of the Paléozoïque: the area of Yosemite, located then on a passive continental terrace, is slowly covered by sedimentary deposits. Between the end of the Dévonien and during the Permian , the Laurentia (ancestor of the North-American plate), pushes towards the west and enters in Collision with the oceanic plate of Farallon. This process gives rise to a volcanic insular arc; by the play of the Plate tectonics , oceanic space disappears gradually and the insular arc névadien is found welded with the continental Plaque.

Magmatic intrusions and subduction

During the Mesozoic, the Orogenèse névadienne affects the West of North America and built an assembly line of an altitude of 4500 meters, ancestor of current Sierra Nevada. The sedimentary rocks are carried in altitude. Orogenesis is accompanied by phenomenon Volcan ic and increase of Magma: a first phase of regional plutonism starts at the end of the Trias and continues until the Jurassic , approximately 150 million years ago. It is in this context that plutons them cool very slowly to constitute Batholite S, to approximately 10 km of depth. The second phase of plutonic formation of rock is spread out of 120 million to 80 million years. At the end of the Cretaceous , the erosion and the rising of the grounds put at the day the masses granite.

Between 20 and 5 million years before our era, of the volcanic phenomena affects north and is of Yosemite: the geologists found traces of spreading of Lave and Cendre S, as well as basaltic Orgues.

Rising of the Nevada Sierra and glacial erosion

There are 10 to 20 million years, the Nevada Sierra starts to be raised by the east where appear many Faille S active. The oriental party of the chain rises abruptly above current the Vallée of Owens, whereas the Western slope is formed soft inclined. This rising causes the cashing of the rivers: it is at that time that the river Vallée S grow hollow with a profile in “V”. It causes also cracks and Diaclase S in the granite which facilitates the work of erosion. Following the phases of cooling of the quaternary era, Glacier S are formed and eroded the valleys by modifying their profile (in “U” or “glaciated valleys” such as the valleys of Hetch Hetchy or Yosemite). These last have a flat and broad bottom, sometimes occupied by lakes. The walls which frame them are escarpées and form by places of true Falaise S. Enfin, the Moraine S represent the traces most characteristic of the glacial past of the area.

The specialists allot names to the periods of Glaciation; those which have affected Yosemite are Sherwin (or pre-Tahoe), Tahoe, Tenaya and Tioga.

The current glaciers were formed during the Petit Ice Age; they are in circuses exposed to north and very high-altitude. But the current Climate warming tends to make them disappear.

History of Yosemite

Ahwahneechee

Approximately 4000 years ago, the Amerindian S miwoks and paiutes occupies the area, after being sedentarized. They tie bonds with the close tribes and make come from the areas located at the east of the Nevada Sierra of the pinions, the obsidian and other products. They use baskets rather than potteries to store and exchange their goods. Some of these objects are visible with the museum of Yosemite, as well as the reconstitution of one their villages. The Ahwahneechee tribe which lives in the valley of Yosemite and comes into contact with the colonists at the 19th century, go down from Miwoks.

Carried out by John Walker, the first trappers attend the Nevada Sierra as of the Années 1830; starting from 1848, the discovery of the Or in California attracts the adventurers of the east of the country. In 1851, the State of California lately created decides to send a battalion. The unit is directed by major John Savage and built a fort. The Amerindians, fearing to be submerged, attack the Americans: it is the “Indian war of Mariposa”. They end up being overcome. They are initially gathered in a reserve close to Fresno (California) before returning in the valley of Yosemite. After having attacked gold diggers in spring 1852, Ahwahneechee take refuge in the tribe close to Monos but end up being massacred.

The name of the area would have been allotted by Doctor Lafayette Bunnell, which accompanied the company by John Savage. The doctor had discussed with the chief Ahwahneechee, Chief Tenaya, and had consigned in writing his talks and his impressions. Ahwahneechee were regarded as particularly wild: the word miwok " yohhe' meti" meant literally “they are killers. ” The letters and the articles written by the members of the battalion then contributed to diffuse the mot.

First tourists

In second half of the 19th century, the reputation of the valley of Yosemite attracts already many visitors. James Madison Hutchings understands quickly that tourism is an important source of incomes and becomes one of the first contractors of the area. A first hotel is built in 1856, followed by others, like Wawona Hotel in 1879; constructions multiply quickly, of many trees are cut and the breeding is introduced on the meadows, threatening balance of the ecosystem S.

It is at that time that the photographers Charles Leander Weed, Carleton Watkins and Robert Vance take stereotypes of the valley of the Yosemite. Watkins publishes stereoscopic photographs in the Années 1860.

Galen Clark, which discovered Mariposa Grove, and the senator John Conness militate in favor of the protection of Yosemite. In 1864, the president of the United States Abraham Lincoln decides to protect the valley from Yosemite like Mariposa Grove of the private interests by decree: it creates the first regional park of the country. In 1866, the federal government of California names Galen Clark like first guard of Yosemite. But he dies six months afterwards, and is buried in the cemetery of the park. In 1869, the First railroad transcontinental connects the two coasts of the United States; the number of visitors exceeds the thousand for the first time at Yosemite: success will do nothing but grow thereafter. In 1879, the first vault - still upright today - is set up.

National nature reserve

Thanks to the determination of the naturalist John Muir (1838 - 1914) and of Robert Underwood Johnson (1853 - 1937, editor association of the magazine Century ), a vast space around the valley of Yosemite is transformed into national nature reserve on October 1st, 1890: it is the third of the United States and its first director is Frederick Law Olmsted (1822-1903). The State of California continues to manage the valley and Mariposa Grove; military troops are installed in Wawona. In May 1903, John Muir and Theodore Roosevelt camp together close to Glacier Not. He convinces the President to entrust the whole of the park to the Federal state, which is made in 1906. Starting from 1916, the park is managed by the National Park Service.

At the beginning of the 20th century, the town of San Francisco develops and wishes to build a stopping on Tuolumne, in the north-western part of the park; the objective is to supply the water agglomeration and to produce electricity. The stopping becomes a major policy issue and, in spite of the efforts of John Muir, the valley of Hetch Hetchy is flooded in 1913 following the installation of the stopping O' Shaughnessy.
Yosemite is made known thanks to the photographer Ansel Adams (1902 - 1984). In 1907, the construction of a railway line between Merced and El Portal, the south-western entry of the park, brings more tourists. In addition, the cars are increasingly numerous in the valley of Yosemite and the environment is degraded. The number of visitors passes from: 10,000 in 1905 to a million in 1954 and two million in 1976. In the Years 1970, circulation is prohibited in the part is valley of Yosemite. Shuttles of bus are installation and the tourists are invited to leave their car to the carpark.

Yosemite is registered with the world heritage of humanity (UNESCO) since 1984. The natural environment of the park is fragile : fires are declared regularly the summer, certain species are threatened. So much so that the Californian authorities plan to close the park and to make a natural sanctuary of it. In 1997, the park is closed with the public during six weeks because of Inondation S catastrophic.

Today, the park is with the permanent search for balance between protection of nature and reception of the public. Certain conservationists would like to prohibit the motor vehicle traffic to make disappear the atmospheric pollution which stagnates in the valley of Yosemite in summer. Activities of education and sensitizing to the ethics of management and the natural heritage are carried out near the visitors. The State of California recently decided to destroy the stopping of the valley of Hetch Hetchy.

Flora

The vegetation of the park is staged and depends on altitude as well as exposure to the sun. The Gradient of altitudes rising towards the east, it is in the latter sector that one will find the mediums most constraining, with more than 3000 meters. The western margin of Yosemite is dominated by mixed forests of conifers (Pin ponderosa, Pin of Jeffrey, Pin twisted, silver fir, fir tree Douglas and the Cèdre with incense) and trees with persistent sheets (Cornouiller of the mountains, black Chêne of California, white alders, maple, Saule, Peuplier balsam tree, Laurier of California, etc). But the largest tree of the forests of the Nevada Sierra is the Giant sequoia, which pushes for example in the thicket of Mariposa.

With the subalpine stage, the forests of conifers become prevalent (red Sapin, Pin silver plated, Pin of Jeffrey, Pin twisted, Pin of Balfour) and less abundant fauna. Beyond 2500 meters (alpine stage), the trees are rarer and smaller. The landscape becomes more mineral, with granite outcrops. The vegetative season is short and the winters are hard. The trees most adapted to these conditions are the Pin twisted, the Pin with white bark and the subalpine Pruche. The slopes are colonized by plants with flowers and the Pelouse.

The park of Yosemite has many wet meadows where various wild flowers push: the lilac, the common Cirse, the Rocks woolly, the Lupin, the Solidago, the wild iris, Achillée cream slice, the Azalée and the asclépiade. The Calochortus and the Violette of the mountains prefer the shade of the forests.

Flora of the park of Yosemite: , of which fish, Amphibians, birds and mammals. The diversity of fauna is due also to the fact that Yosemite is a completely preserved zone of the economic activities and human habitat.

Mammals

Yosemite is populated by 80 species of Mammifère S. the Opossum of Virginia is only the alive Marsupial inside the park. It colonized California at the beginning of the 20th century. One counts seven species of Musaraigne S, including one endemic (the Musaraigne of the Lyell Mount) and 17 of bat; the black bear is smaller than the Grizzli, which completely disappeared from the Nevada Sierra at the beginning of the 20th century. They were killed because they represented a threat for the colonists. In same time, the black bears thrived because their less aggressive behavior preserved them hunting. In the absence of a scientific census to know the number of bear in the park of Yosemite, one estimates their population at a fork between 300 and 500 individuals. The foresters (To arrange S) count it about fifteen in the valley Yosemite, i.e. the sector more attended by the tourists. The food mode of the black bear is varied: in spring, it nourishes grasses, roots, and insects (Termite S, ants, towards) found in the meadows. In summer, it consumes bays and in autumn, nipples to prepare its Hibernation. However, the black bear adapts easily to the presence of human and does not scorn their food. It can thus penetrate in the camp-sites and the vehicles parked on the carparks.

Formerly, the bears were nourished by the men, avac for making result of the attacks of many casualties. Today, of many panels of information and the messages of prevention disadvise nourishing the wild animals, in particular the plantigrades. The dustbins of the park were consolidated and closed hermetically; boxes were arranged in the camp-sites to store food. The incidents are falling, however two to three aggressive bears must be shot down each year.

Mammalian of the park of Yosemite: .

The Peak glandivore, the Pigeon with barred tail, the Large-duke of America and the Pic épeichette live in the forests of oaks. The Quiscale de Brewer, the Carouge with shoulder pads, the Lappish Owl and the Moineau prefer the wet meadows. The trip hammer S nest in granitic cliffs. The Kingfisher of America and the Cinclus of America and the Canard S fish in the rivers. The brown Creeper, the Sittelle with russet-red chest and the Sittelle with white chest climb with the trees. The Around the wood pigeons and the Cassenoix of America live in the highest sectors.

Birds of the park of Yosemite: : the Lizard of the palisades, the boreal Lizard-alligator, the Lizard-alligator of the south and the Thamnophis are widespread specimens. Among all the species of snakes of the area, only the Crotale of the west is poisonous; it nourishes rodents.

Poisson

For the periods of glaciation, the area could not shelter any fish; after the cast iron of the glaciers, the water falls prevented fish from colonizing is of Yosemite. The majority of the current species were introduced by the Man, except for the Rainbow trout, which was present in the lower courses of Tuolumne and Merced before the arrival of Europeans. Today, the most abundant species are the Saumon of fountain and the Truite fario. However, a great number of fish introduced into the lakes did not survive because of the climatic conditions, the lack of food and the absence of sectors of abrasion. The introduction of invasive species had heavy consequences on the watery ecosystem S of the park.

Management and administration of the park

Administration

The national park of Yosemite belongs to the area of the western Pacific, which is under the responsibility of a regional director. It is directed by one “superintendant”, Stanley T. Albright. This last control the activities (information of the visitors, programs educational, environmental protection) and administration of the park (service, budget, staff management). The Ranger S are most of the time on the ground: they take care of the safety of the visitors, inform them and guide them in the park.

Organizations and associations

In addition to the administration of the National Park Service , there exist other actors who enter the management of Yosemite. The Yosemite Association is devoted since the beginning of the 20th century with the financing of activities, publication and services. The Sousson Foundation , the Student Conservation Association , the Yosemite Concession Services , the San Francisco Conservation Body or the Sierra Club act in.liaison.with the authorities of the park in order to make known and to protect the area from Yosemite. The Yosemite Fund is a Association created in 1988 and based with San Francisco, whose objective is to collect funds for the safeguarding of the park. Since its foundation, it contributed to various projects for an entire amount of 13 million dollars.

Prevention and role of the fires

Since 1970, prevention plans of the fires ( fire management plans) are regularly prepared for the park. They are the result of dialog between the various actors of the park and the local or federal agencies.

The campfires are strictly regulated inside the park: the season of the fires generally begins in May. It coincides with the summer period during which the combined effects of the Sécheresse, a low water content of the grounds and presence of an important tourist population support the blossoming of fires. Each year of the starting points of fire are caused by the negligence of the visitors and are fought by the firemen of Yosemite and the personnel of the California Department off Forestry .

The fires also start because of the Foudre. The authorities of the park let some of them extend, the specialists having shown the benefits in fire for the regeneration of the ecosystem. For a long time indeed, one protected from the fire of the whole sectors, so that the branches and the accumulated dead trunks constitute a dangerous fuel in the event of fire. The sequoias, very many in the park, are protected from fire thanks to their bark.

The administration can decide to light the fires controlled in strictly defined sectors. These controlled fires should not threaten the historical heritage, the safety of the visitors and the inhabitants of the park; they are organized when all the conditions are met: absence of wind, important of the firemen, alert mobilization with the public, etc On the grounds belonging to the federal state ( federal Lands ) these fires must respect the National Environmental Policy Act . As of the time précolombienne, the Miwoks Indians practiced already the burn-beating with an aim of regenerating the flora and of supporting the black Chêne, which needs much light.

Interesting sites

Water falls

See also: List of the water falls of Yosemite

The park offers several tens of falls of water. It is at the end of spring that they are most beautiful, when they are fed by the snow melt and of the Glacier S. ten of these falls exceed the 200 meters height. The Yosemite Falls are the greatest water falls of North America, and the larger fifths of the world. Of a total of 740 m, they break up into three stages: Upper Yosemite Fall, Middle Cascade, Lower Yosemite Fall. A path gives access their base, another to go up up to the point of fall. Other cascades are visible since the valley of Yosemite: Bridalveil Fall (literally “falls of the wedding veil”) measures 189 meters.

Granitic domes

The emblem of the park is the Half Dome (“half dome”), a granitic block whose segment of a sphere is distinct. Surface is to 2700 m of altitude; it is accessible in summer by a vertiginous way. The mountaineers prefer to climb the 670 height m abrupt wall and which never deviate of more than 7° vertical. But in top the sight is absolutely splendid, one has a unspoilable view on all the valley. El Capitan offers a 900 height m wall, which makes of it most whole cliff of the world. Almost all the year, of climbing of the whole world climb this granitic rock. There exists more than 70 possible routes to join the top of it. Cathedral Peak is a shredded granitic peak which culminates to 3222 Mr.

Lakes, rivers and meadows wet

Glacier Not is the most beautiful point of view of the area: perched over a cliff, it dominates of the valley of Yosemite of more than 900 meters in height. The road which reaches Glacier Not is closed from November to May, because of the climatic conditions. But it is possible to join the site in Ski touring.

Mariposa Grove, in the south of the park is a thicket of 200 Séquoia S giants. Oldest of these trees is the Grizzly sequoia, 2700 years old). Footpaths, more or less difficult, leave the road and the information center. One can thus join camp-sites located at 12/16 kilometers. The road climbs until an altitude of 3000 m in Tioga Pass, in the east of the park. To this place, a way goes up to 3200 m of altitude then goes down again in Middle Gaylor Lake before arriving at the ruins of a stone hut, which constitutes the remainders of a mine of money exploited at the 19th century.

Practical information

Access and transport

The two airports closest to the park of Yosemite are those of Fresno (to 120 km in the south) and of Merced (to 112 km in south-west). Since San Francisco, it is possible to plan one day in the bus. Lastly, a railway station is in the town of Merced.

There exist four main entrances which give access the park by the road, but the entry located at the east ( Tioga Pass Fan-in ) is open only of at the end of May mid-November because of snow. Since Merced, it is necessary to borrow California Highway 140 until Arch Rock Fan-in. Since the west, California Highway 120 arrives until Oak Flat Entrance. While coming from the south by Fresno, California Highway 41 leads to the southern entry. There is no service station in the park.

Inside the park, it is possible to use the shuttles of bus (valley of Yosemite all the year; Wawona and Tuolumne Meadows the summer), to make stroll with horse and to rent bicycles. The access of the park is interdict to the trucks.

Tourism

The entry is paying (20 dollars per vehicle for seven days). Eighteen camp-sites make it possible to sleep in the park, but it is necessary to hold often a long time in advance, especially for the summer period. In the valley of Yosemite, the village proposes many services (station, supermarket, sale of food, charts, books, showers, automatic teller machine…). An information center exposes the geological history of the park and proposes the free visit of an Amerindian museum. One finds there also several hotels ( The Ahwahnee ; Curry Village ; Yosemite Lodge ).

The park offers a large variety of activities of outdoor: a few 1280 km of hiking trails make it possible to discover the sites close to the valley of Yosemite. For the Trekking S of more than one day, it is obligatory to prevent the rangers dates and course. All the sports of mountain are practicable (Ski touring in winter, Alpinisme, Rafting, Canyoning, fishing, bathe the summer, bicycle…).

Appendices

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