Half Dome
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Half Dome is a at the eastern end of Yosemite Valley, possibly the Valley's most familiar sight. The granite crest rises more than 4,737 feet (1,440 m) above the Valley floor.
As late as the 1870s, Half Dome was considered completely unclimbable, but it may now be ascended in several different ways. Thousands of hikers reach the top each year by following a trail from the valley floor. The trailhead is only two miles from Half Dome itself, but the circuitous route is 8.5 miles (13.5 kilometres) long. The final ascent is accomplished by following a pair of metal cables raised on posts up the peak's steep but somewhat rounded east face. The cable route was constructed in 1919.
Alternatively, over a dozen rock climbing routes lead from the valley up Half Dome's vertical northwest face. Other routes ascend the south face and the west shoulder. The first route climbed was the Regular Northwest Face route - originally climbed in 1957 by Royal Robbins, Mike Sherrick, and Jerry Gallwas. This 5-day ascent was the first Grade VI climb in the United States.
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. What probably happened is that frost splitting of the rock at the back of a tiny glacier against Half Dome above Mirror Lake gradually quarried back the steep northwest face. As the base of the cliff was hewn away, ultimately parts of the sheets parallel to the original upper surface of Half Dome were left projecting outward at the crest of the vertical cliff.
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 dialect 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.
Half Dome is the logo for Sierra On-Line.
Pictures
External links
- [Geologic Story of Yosemite National Park] by N. King Huber, USGS (adapted PD source)
- [Half Dome on Summitpost.org]
- [Hiking Half Dome Report]
- [Hiking Half Dome on OutdoorDB.org]
- [Maps and aerial photos]
- * WikiSatellite view at [WikiMapia]
- * Topographic map from [TopoZone]
- * Aerial image from [TerraServer-USA]
- * Surrounding area map from [Google Maps]
- * Location in the United States from the [Census Bureau]
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