Yosemite is a United States national park located in the state of California. Geographically it is in the eastern and central part of the state in the Sierra Nevada mountain range. It has portions in Tuolumne, Mariposa and Madera counties. Yosemite covers an area of 1,189 square miles (3,080 sq km). It is one of the most famous national parks in the U.S. and nearly 4 million people visit it per year to see its famous glacial carved valley, waterfalls and granite rock formations.
Yosemite was designated as a UNESCO World Heritage Site in 1984 because of its geology, biodiversity and history. About 95% of the park is considered wilderness which ranges from dense forest in its lower elevations to alpine in places like Tioga Pass (the highest mountain pass in the Sierra Nevada and California) at 9,941 feet (3,031 m).
History of Yosemite
In 1855 James Mason Hutchings, an entrepreneur and Thomas Ayres, an artist, were some of the first people to visit Yosemite and as a result, they were also some of the first to publicize it.
In 1857, a settler named Galen Clark discovered the Mariposa Grove of Giant Sequoias. Later, Clark and Senator John Conness became concerned that Yosemite would need to be protected from over-tourism and the growth of commercial interests. On June 30, 1864, President Abraham Lincoln signed the Yosemite Grant which represented the first time that the federal government had set aside park land for preservation. Shortly thereafter, Yosemite Valley and the Mariposa Grove were given to California to become a state park. After it became a park, tourism to Yosemite increased and in 1879, the Wawona Hotel was built to house tourists visiting the Mariposa Grove.
As tourism grew in Yosemite, naturalist John Muir began to write articles analyzing how Yosemite Valley may have formed. He was the first to claim that the valley was carved by glaciers. In the early 1900s and late 1800s, Muir and the Sierra Club began to push the federal government to make Yosemite a national park similar to Yellowstone (the first national park). In 1903, President Theodore Roosevelt visited camped in the area with Muir and he was convinced to take the land from California and make it a federally maintained park, which he did in 1906.
In 1916, the National Park Service was founded and control of Yosemite went to it. In that same year, several campgrounds and Tioga Pass Road were completed and tourism to the park increased. In 1927, the famous Ahwahnee Hotel was constructed and in 1984, the California Wilderness Act designated about 89% of the park as the protected Yosemite Wilderness.
Geology of Yosemite Valley
As Muir said, Yosemite's most famous location, Yosemite Valley was mainly created into its U-shape by glaciers. Beginning about 2 to 3 million years ago a series of glaciations began to modify the uplifted rock of the Sierra Nevada. Most geologic evidence suggests that there were four major glaciations that occurred in the Sierra Nevada. These were the Sherwin, Tahoe, Tenaya and Tioga. The largest and earliest of these was the Sherwin and it is believed that its glaciers were the largest and that they filled most of Yosemite Valley (which had been carved by water).
As the glaciers moved out of the mountains, they scoured the granite until they formed the U-shaped valley present today. Glacial carving of Yosemite ended about 10,000 years ago with the last glaciations. Although glaciers are not present in Yosemite Valley today, it continues to be shaped by natural processes. The Merced River currently runs along the valley floor and continues to shape it via erosion.
Geography of Yosemite
Yosemite is located in the central part of the Sierra Nevada and it is surrounded by the Ansel Adams, Hoover and Emigrant wilderness areas. It covers 1,189 square miles (3,080 sq km) and it has thousands of lakes, 800 miles (1,300 km) of hiking trails and 350 miles (560 km) of roads. The Merced and Tuolumne rivers are designated as Wild and Scenic Rivers and both begin within Yosemite.
Yosemite Valley is at an elevation of about 4,000 feet (1,200 m) while some of the park's higher elevations exceed 10,000 feet (3,048 m). Yosemite's most famous landmark, Half Dome, rises 4,788 feet (1,459 m) above the valley floor. In addition because of its steep granite walls, Yosemite has a large number of waterfalls. The highest of these Yosemite Falls (the highest waterfall in North America), which drops 2,425 feet (739 m).
Yosemite's climate is considered Mediterranean and as such, most of its precipitation occurs in the winter and late fall. Average temperatures vary based on location and elevation. In the high country, Yosemite's average temperatures are mild in the summer and very cold in the winter. In the valley, the average temperatures vary from about 46°F (8°C) in the winter to about 90°F (32°C) in the summer.
Biodiversity of Yosemite
Yosemite has a wide variety of habitat types that vary with elevation. This results in a wide range of plant and animal biodiversity. It has mixed coniferous forests which a few areas of Giant Sequoia as well as oak woodlands. At higher elevations, trees become more spread out but there are a variety of grasses and low-lying plants.
There are also many types of animals in Yosemite. Black bears, mountain lions, mule deer, marmots, pika and a number of different species of reptile and other rodents are common in the park.
To learn more about Yosemite, visit the official website from the National Park Service and an Overview of Yosemite National Park from About.com's National and State Parks.
References
Wikipedia.org. (15 November 2010). Yosemite National Park - Wikipedia, the Free Encyclopedia. Retrieved from: http://en.wikipedia.org/wiki/Yosemite_National_Park