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==Geology==
==Geology==
[[File:Half Dome10.jpg|thumb|250px|left|Half Dome from Washburn Point, showing its profile]]
[[File:Half Dome10.jpg|thumb|250px|left|Half Dome from Washburn Point, showing its profile]]
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 Washburn Point, Half Dome can be seen as [[arête|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 [[Joint (geology)|joints]], 80 percent of the northwest "half" of the original dome may well still be there.
Half Dome is nearly as whole as it ever was.{{cn}} The impression from the valley floor that this is a round dome which has lost its northwest half is an illusion. From Washburn Point, Half Dome can be seen as [[arête|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 [[Joint (geology)|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 {{convert|1,500,000|ft3|m3|}} occurred from Ahwiyah Point.<ref>{{cite web|url=http://www.nps.gov/yose/parknews/ahwiyahrockfall.htm|title=Ahwiyah Point Rockfall Size Estimated|publisher=National Park Service}}</ref> 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 an earthquake reaching 2.5 on the [[Richter Scale]].<ref>{{cite web|url=http://climbing.about.com/b/2009/03/30/yosemite-rockfall-near-half-dome.htm|title=Yosemite Rockfall Near Half Dome}}</ref>
On March 28, 2009, a large rock slide of {{convert|1,500,000|ft3|m3|}} occurred from Ahwiyah Point.<ref>{{cite web|url=http://www.nps.gov/yose/parknews/ahwiyahrockfall.htm|title=Ahwiyah Point Rockfall Size Estimated|publisher=National Park Service}}</ref> 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 an earthquake reaching 2.5 on the [[Richter Scale]].<ref>{{cite web|url=http://climbing.about.com/b/2009/03/30/yosemite-rockfall-near-half-dome.htm|title=Yosemite Rockfall Near Half Dome}}</ref>

Revision as of 17:50, 22 April 2013

Half Dome
Sunset over Half Dome from Yosemite Valley
Highest point
Elevation8840+ ft (2694+ m)[1]
Prominence1,360 ft (410 m)[1]
Parent peakClouds Rest[1]
Geography
RegionUS
Parent rangeSierra Nevada
Topo mapUSGS Half Dome
Geology
Age of rockCretaceous, 93 Myr
Mountain typeGranite dome
Climbing
First ascent1875 by George G. Anderson
Easiest routeCable route

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 from Washburn Point, showing its profile

Half Dome is nearly as whole as it ever was.[citation needed] The impression from the valley floor that this is a round dome which has lost its northwest half is an illusion. 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 from Ahwiyah Point.[3] 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 an earthquake reaching 2.5 on the Richter Scale.[4]

In culture

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.[5] Tis-sa-ack is the name of a Mono Lake Paiute Indian girl in the Yosemite Native American legend.[citation needed] John Muir referred to the peak as "Tissiack".[6]

An image of Half Dome, along with John Muir and the California Condor, appears on the California State quarter, released in January 2005. Starting October 2010, an image of Half Dome is included on the new revised California drivers license in the top right-hand corner.

Half Dome is also an element or inspiration of various company and organization logos, including that of The North Face outdoor product company, the Sierra Club environmental group and the Sierra Entertainment game studio.

Ascents

As late as the 1870s, Half Dome was declared "perfectly inaccessible".[7] The summit was finally conquered by George G. Anderson in October 1875, via a route constructed by drilling and placing iron eyebolts into the smooth granite.[8]

Hikers use cables to ascend Half Dome

Today, Half Dome may now be ascended in several different ways. Thousands of hikers reach the top each year by following an 8.5 mi (13.7 km) trail from the valley floor. After a rigorous 2 mi (3.2 km) approach including several hundred feet of granite stairs, the final pitch up the peak's steep but somewhat rounded east face is ascended with the aid of a pair of post-mounted braided steel cables originally constructed close to the Anderson route in 1919.

Alternatively, over a dozen rock climbing routes lead from the valley up Half Dome's vertical northwest face. The first technical ascent was in 1957 via a route pioneered by Royal Robbins, Mike Sherrick, and Jerry Gallwas today known as the Regular Northwest Face. Their 5-day epic was the first Grade VI climb in the United States.[9] Their route has now been free soloed several times in a few hours time. Other technical routes ascend the south face and the west shoulder.

Hiking the Cables Route

Climbers on The Visor atop Half Dome, looking down (west) into Yosemite Valley.

The Half Dome Cables Route hike runs from the valley floor to the top of the dome in 8.2 mi (13 km) (via the Mist Trail), with 4,800 ft (1,460 m) of elevation gain. The length and difficulty of the trail used to keep it less crowded than other park trails, but in recent years the trail traffic has grown to as many as 800 people a day.[10] The hike can be done from the valley floor in a single long day, but many people break it up by camping overnight in Little Yosemite Valley. The trail climbs past Vernal and Nevada Falls, then continues into Little Yosemite Valley, then north to the base of the northeast ridge of Half Dome itself.

The final 400 ft (120 m) ascent is steeply up the rock between two steel cables used as handholds.[11] The cables are fixed with bolts in the rock and raised onto a series of metal poles in late May (the poles do not anchor the cables). The cables are taken down from the poles for the winter in early October, but they are still fixed to the rock surface and can be used. The National Park Service recommends against climbing the route when the cables are down and when the surface of the rock is wet and slippery.[11] The Cable Route is rated class 3, while the same face away from the cables is rated class 5.[12]

The cable route gets crowded on the weekends

The cable route can be crowded. In past years, as many as 1,000 hikers per day have sometimes climbed the dome on a summer weekend, and about 50,000 hikers climb it every year.[13][14]

In January 2010, the National Park Service announced that permits will be required to hike the cable route on Fridays, Saturdays, Sundays and federal holidays. The park service cited safety concerns and increased crowding on the route as reasons for the new regulations. Permits will be issued only through the National Recreation Reservation Service from four months in advance to one week in advance. A maximum of 400 permits per day will be issued, and a processing fee of $1.50 per permit will be charged. Permits will not be issued in the park.[15]

In December 2010, NPS officials announced that the permit system would be expanded to seven days per week beginning with the 2011 ascent season. All hikers who intend to ascend the cable route must now obtain permits before entering the park.[15] Permits will be checked by a ranger on the trail, and no hikers without permits are allowed to hike beyond the base of the sub-dome or to the bottom of the cables. Hikers caught bypassing the rangers to visit either the sub-dome or main dome without a permit face fines of up to $5000 and/or 6 months in jail.[16]

Backpackers with an appropriate wilderness permit can receive a Half Dome permit when they pick up their wilderness permit with no additional reservation required. Rock climbers who reach the top of Half Dome without entering the subdome area can descend on the Half Dome Trail without a permit.[15]

The top of Half Dome is a large, flat area where climbers can relax and enjoy their accomplishment. The summit offers views of the surrounding areas, including Little Yosemite Valley and the Valley Floor. A notable location to one side of Half Dome is the "Diving Board," where Ansel Adams took his photograph, "Monolith, The Face of Half Dome" on April 10, 1927. Often confused with "The Visor," a small overhanging ledge at the summit, the Diving Board is on the shoulder of Half Dome.[17]

From 1919 when the cables were erected through 2011, there have been six fatal falls from the cables.[13][14][18] The latest fatality occurred on July 31, 2011.[19]

Lightning strikes can be a risk while on or near the summit. On July 27, 1985, five hikers were struck by lightning, resulting in two fatalities.[20]

Notable ascents

Half dome and Yosemite from a plane
  • 1875 George Anderson via drilled spikes on the east slope.[8]
  • 1946 Salathe Route on southwest face (IV 5.7 A3), FA by John Salathe and Anton Nelson[21]
  • 1957 Northwest Face (VI 5.8 A3), FA by Royal Robbins, Jerry Gallwas and Mike Sherrick. First Grade VI in North America.[22]
  • 1963 Direct Northwest Face (VI 5.9 A5), FA by Royal Robbins and Dick McCracken[23]
  • 1969 Tis-sa-ack (VI 5.9 A4), FA by Royal Robbins and Don Peterson.[23]
  • 1987 The Big Chill (VI 5.9 A4), FA by Jim Bridwell, Peter Mayfield, Sean Plunkett and Steve Bosque[24]
  • 1989 Shadows (VI 5.10 A5), FA by Jim Bridwell, Charles Row, Cito Kirkpatrick, William Westbay[25]
  • 1997 Blue Shift (VI 5.11c a4) FA by Jay Smith and Karl McConachie.[26]

Notable free climbs

  • 1964 Salathe Route (5.10), FFA by Frank Sacherer, Bob Kamps & Andy Lichtman[21]
  • 1965 Snake Dike (5.7), FFA by Eric Beck, Jim Bridwell and Chris Fredericks[27]
  • 1976 Regular Northwest Face, Higbee variation (VI 5.12) by Art Higbee and Jim Erickson.[28]
  • 1988 Southern Belle (V 5.12d) by Dave Schultz and Scott Cosgrove[24]
  • 2008 Regular Northwest Face, Higbee variation (VI 5.12a, 23 pitches), free solo climb by Alex Honnold.[29]

See also

360° panorama from the summit of Half Dome, taken in July 2005

References

  1. ^ a b c "Half Dome, California". Peakbagger.com. Retrieved 2012-03-30.
  2. ^ "Half Dome". Geographic Names Information System. United States Geological Survey, United States Department of the Interior. Retrieved 2012-03-30.
  3. ^ "Ahwiyah Point Rockfall Size Estimated". National Park Service.
  4. ^ "Yosemite Rockfall Near Half Dome".
  5. ^ Wilson, Herbert Earl (1922). "Legend of Tis-sa-sack". The Lore and Lure of Yosemite.
  6. ^ Muir, John (1918). "A Geologist's Winter Walk". Steep Trails. Boston: Houghton-Mifflin. ISBN 0-87156-535-8. I have gazed on Tissiack a thousand times — in days of solemn storms, and when her form shone divine with the jewelry of winter, or was veiled in living clouds; and I have heard her voice of winds, and snowy, tuneful waters when floods were falling.
  7. ^ Jones, Chris (1976). Climbing in North America. Berkeley, California: American Alpine Club / Univ of California Press. p. 26. ISBN 0-520-02976-3.
  8. ^ a b Jones, Chris. Climbing in North America. p. 27. ISBN 0-520-02976-3.
  9. ^ Jones, Chris. Climbing in North America. pp. 207–211. ISBN 0-520-02976-3.
  10. ^ "Half Dome Permits". Yosemite National Park. U.S. National Park Service.
  11. ^ a b "Half Dome Day Hike". Yosemite National Park. National Park Service. Retrieved 2007-08-12.
  12. ^ Secor, R.J. (1999). The High Sierra: Peaks, Passes, and Trails (2nd ed.). The Mountaineers. p. 391. ISBN 0-89886-313-9.
  13. ^ a b "Death of Sunnyvale hiker on Half Dome called unusual". San Jose Mercury News. 2007-06-19.
  14. ^ a b "Hiker falls to death from Yosemite's Half Dome".
  15. ^ a b c "Yosemite National Park: Half Dome Permits". National Park Service. Retrieved 2011-08-20.
  16. ^ "Yosemite will require permits for Half Dome hikes, starting in May". LA Times. February 1, 2010. Retrieved 14 December 2010.
  17. ^ "NPS: Ansel Adams in Yosemite National Park".
  18. ^ Ghiglieri, Michael P. and Farabee, Charles R. "Butch", Jr. (2007). Off the Wall: Death in Yosemite. Flagstaff: Puma Press. pp. 184–200. ISBN 0-9700973-7-9.{{cite book}}: CS1 maint: multiple names: authors list (link)
  19. ^ "Hiker Fatality on Half Dome Cables in Yosemite National Park". National Park Service.
  20. ^ "Lightning at Yosemite's Half Dome Kills 2 Climbers; 3 Hurt". Los Angeles Times. July 29, 1985.
  21. ^ a b Roper, Steve (1971). A Climber's Guide to Yosemite Valley. San Francisco, USA: Sierra Club Books. p. 178. ISBN 87156-048-8. {{cite book}}: Check |isbn= value: length (help)
  22. ^ Roper, Steve (1971). A Climber's Guide to Yosemite Valley. San Francisco, USA: Sierra Club Books. pp. 174–176. ISBN 87156-048-8. {{cite book}}: Check |isbn= value: length (help)
  23. ^ a b Roper, Steve (1971). A Climber's Guide to Yosemite Valley. San Francisco, USA: Sierra Club Books. p. 176. ISBN 87156-048-8. {{cite book}}: Check |isbn= value: length (help)
  24. ^ a b Reid, Don (1993). Yosemite Climbs, Big Walls. Evergreen, CO, USA: Chockstone Press. p. 205. ISBN 0-934641-54-4.
  25. ^ Bridwell, Jim (1991). "Shadows - Half Dome". American Alpine Journal. 33 (65). New York, NY USA: American Alpine Club: 118–123. ISBN 0-930410-46-7.
  26. ^ Smith, Jay (1998). "Half Dome, Blue Shift". American Alpine Journal. 40 (72). New York, NY USA: American Alpine Club: 188. ISBN 0-930410-78-5.
  27. ^ Roper, Steve (1971). A Climber's Guide to Yosemite Valley. San Francisco, USA: Sierra Club Books. p. 179. ISBN 87156-048-8. {{cite book}}: Check |isbn= value: length (help)
  28. ^ Reid, Don (1993). Yosemite Climbs, Big Walls. Evergreen, CO, USA: Chockstone Press. p. 204. ISBN 0-934641-54-4.
  29. ^ Erik Lambert (September 9, 2008). "Updated: Honnold Free Solos Half Dome 5.12". Retrieved 15 April 2011.
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