Yosemite National Park is an American national park in the western Sierra Nevada of Central California, with a perimeter that is surrounded on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The park is operated by the National Park Service, and encompasses a total area of 748,436 acres (1 with 3,029 km2). The majority of this land is located in Tuolumne and Mariposa counties, while a smaller area extends north and east to Mono and south to Madera County. Yosemite was inscribed as a World Heritage Site in 1984, and as a result, it is widely recognized for its granite cliffs, waterfalls, clear streams, giant sequoia groves, lakes, mountains, meadows, glaciers, and biological diversity. Only a little more than one percent of the park area is designated as designated wilderness.
One of the largest and least fragmented ecosystems in the Sierra Nevada is supported by Yosemite National Park, which helps support a wide range of plant and animal species. The park has an elevation range of from 2,127 to 13,114 feet (648 to 3,997 m) and contains five major vegetation zones: chaparral and oak woodland, lower montane forest, upper montane forest, subalpine zone, and alpine. About half of the 7,000 species of plants in California can be found in the Sierra Nevada, and more than 20% are located within Yosemite. More than 160 unique species live in the park, many of which occupy restricted ranges. Amongst these are various rare geologic formations and distinctive soils, as well as the wide range of plant varieties represented here.
The geology of the Yosemite area is characterized by granitic rocks and remnants of older rock that are still left. The Sierra Nevada is the prominent mountain range in California that sits just west of the Central Valley. During the Paleogene Period, it was uplifted and then tilted to form its relatively gentle western slopes and the more dramatic eastern slopes. When streams and rivers became uplifted, they exposed the bottom of the stream and river beds, resulting in the formation of deep, narrow canyons. A lot of snow and ice built up around one million years ago, leading to the formation of glaciers at the higher alpine meadows that moved down the river valleys. It is likely that the ice thickness in Yosemite Valley may have reached 4,000 feet (1,200 m) during the early glacial episode. While the valley was initially formed as a result of the downslope movement of the ice masses, today the U-shaped valley attracts many visitors because of the valley’s scenic views.
Yosemite played a crucial role in the formulation of the idea of a national park. In order to preserve Yosemite Valley from development, Galen Clark and others lobbied to have it designated as a federal park in 1864, and eventually Lincoln signed the Yosemite Grant which protected the valley. John Muir led a successful movement to have Congress pass legislation establishing a larger national park in the Sierra Nevada Valley by 1890, one which included the valley and its surrounding mountains and forests. This legislation allowed for the creation of the National Park System. At this point, Yosemite draws approximately four million visitors each year, and the majority of visitors spend most of their time in the seven square miles (18 km2) of Yosemite Valley. The park set a new record for annual visitors, with over five million people visiting the park for the first time in its history.