Monday, September 19, 2011

Half Dome

Half Dome is a granite dome in Yosemite National Park, located in northeastern Mariposa County, California, at the eastern end of Yosemite Valley — possibly Yosemite's most familiar rock formation. The granite crest rises more than 4,737 ft (1,444 m) above the valley floor.

Geology

Half Dome is nearly as whole as it ever was. The impression from the valley floor that this is a round dome which has lost its northwest half is an illusion. From Glacier Point or from Washburn Point, Half Dome can be seen as a thin ridge of rock oriented northeast-southwest, with its southeast side almost as steep as its northwest side except for the very top. Although the trend of this ridge, as well as that of Tenaya Canyon, is probably controlled by master joints, 80 percent of the northwest "half" of the original dome may well still be there.

On March 28, 2009, a large rock slide of 1,500,000 cubic feet (42,000 m3) occurred off of Awhiyah Point. The slide happened at 5:26 a.m and damaged a large area under the dome. No one was injured but hundreds of trees were knocked down and a portion of the Mirror Lake trail was buried. The slide registered on seismographs as a 2.5 earthquake.


In culture

An image of Half Dome, along with John Muir and the California Condor, appears on the California State quarter, released in January 2005.

Half Dome was originally called "Tis-sa-ack," meaning Cleft Rock in the language of the local Native Americans. Tis-sa-ack is also the name of the fourth route on the formation, ascended by Royal Robbins and Don Peterson over eight days in October 1969. Tis-sa-ack is the name of a mother from a native legend. The face seen in Half Dome is supposed to be hers. Tis-sa-ack is the name of a Mono Lake Paiute Indian girl in the Yosemite Native American legend. John Muir referred to the peak as "Tissiack".

Half Dome is included in many company and organization logos, including that of the environmental group the Sierra Club and the game studio Sierra Entertainment.

Half Dome is the inspiration behind The North Face corporate logo. Starting October 2010, an image of Half Dome is also included on the new revised California drivers license in the top right-hand corner.

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