Mount Everest

"Everest" redirects here. For other uses, see Everest (disambiguation).

Mount Everest (Qomolongma / Sagarmatha)
Highest Mountain in the World
Everest from Kala Patthar in Nepal
Elevation	8,848 m (29,029 ft) [1] Ranked 1st
Prominence	8,848 m (29,029 ft)  Notice special definition for Everest.
Listing	Seven Summits Eight-thousander Country high point Ultra
Location
Mount Everest Location on the Sagarmatha Zone, Nepal – Tibet, China border
Location	Solukhumbu District, Sagarmatha Zone, Nepal Tingri County, Xigazê Prefecture, Tibet Autonomous Region, People's Republic of China[2]
Range	Mahalangur Himal, Himalayas
Coordinates	27°59′17″N 86°55′31″E / 27.98806°N 86.92528°E / 27.98806; 86.92528Coordinates: 27°59′17″N 86°55′31″E / 27.98806°N 86.92528°E / 27.98806; 86.92528[3]
Climbing
First ascent	29 May 1953 Edmund Hillary Tenzing Norgay
Easiest route	South Col (Nepal)

Mount Everest (Tibetan: ཇོ་མོ་གླང་མ, Chomolungma^[4][5][6] or Qomolangma pronounced /ˈtʃəʊməʊˌlɑːŋmə/ choh-moh-lahng-mə,^[7][6] "Holy Mother"; Chinese: 珠穆朗玛峰; pinyin: Zhūmùlǎngmǎ Fēng; Nepali: सगरमाथा, Sagarmāthā^[8]) is the world's highest mountain, with a peak at 8,848 metres (29,029 ft) above sea level. It is located in the Mahalangur section of the Himalayas. The international boundary runs across the precise summit point. Its massif includes neighboring peaks Lhotse (8516 m), Nuptse (7855 m) and Changtse (7580 m).

In 1856, the Great Trigonometric Survey of British India established the first published height of Everest, then known as Peak XV, at 29,002 ft (8,840 m). In 1865, Everest was given its official English name by the Royal Geographical Society upon a recommendation by Andrew Waugh, the British Surveyor General of India. Waugh named the mountain after his predecessor in the post, Sir George Everest. Although Tibetans had called Everest "Chomolungma" for centuries, Waugh was unaware of this because Nepal and Tibet were closed to foreigners.

The highest mountain in the world attracts many well-experienced mountaineers as well as novice climbers willing to hire professional guides. While not posing substantial technical climbing challenges on the standard route, Everest presents dangers such as altitude sickness, weather and wind.

By the end of the 2010 climbing season, there had been 5,104 ascents to the summit by about 3,142 individuals.^[9] Climbers are a significant source of tourist revenue for Nepal, whose government also requires all prospective climbers to obtain an expensive permit, costing up to US$25,000 per person.^[10] By the end of 2010 Everest had claimed 219 lives,^[9] including eight who perished during a 1996 storm high on the mountain. Conditions are so difficult in the death zone—altitudes higher than 8,000 metres (26,000 ft)—that most corpses have been left where they fell. Some of them are visible from standard climbing routes.^[11]

Identifying the highest mountain

Location on Earth

Mount Everest relief map

Published by the Survey of Nepal, this is Map 50 of the 57 map set at 1:50,000 scale "attached to the main text on the First Joint Inspection Survey, 1979-80, Nepal-China border." In the top center, note the boundary line, identified as separating "China" and "Nepal", passing exactly through the summit contour. The boundary here and for much of the China-Nepal border follows the main Himalayan watershed divide.

In 1808, the British began the Great Trigonometric Survey of India to determine the location and names of the world's highest mountains. Starting in southern India, the survey teams moved northward using giant 500 kg (1,100 lb) theodolites (each requiring 12 men to carry) to measure heights as accurately as possible. They reached the Himalayan foothills by the 1830s, but Nepal was unwilling to allow the British to enter the country because of suspicions of political aggression and possible annexation. Several requests by the surveyors to enter Nepal were turned down.^[12]

The British were forced to continue their observations from Terai, a region south of Nepal which is parallel to the Himalayas. Conditions in Terai were difficult owing to torrential rains and malaria—three survey officers died from malaria while two others had to retire owing to failing health.^[12]

Nonetheless, in 1847, the British pressed on and began detailed observations of the Himalayan peaks from observation stations up to 240 km (150 mi) away. Weather restricted work to the last three months of the year. In November 1847, Andrew Waugh, the British Surveyor General of India made several observations from Sawajpore station located in the eastern end of the Himalayas. Kangchenjunga was then considered the highest peak in the world, and with interest he noted a peak beyond it, some 230 km (140 mi) away. John Armstrong, one of Waugh's officials, also saw the peak from a location farther west and called it peak 'b'. Waugh would later write that the observations indicated that peak 'b' was higher than Kangchenjunga, but given the great distance of the observations, closer observations were required for verification. The following year, Waugh sent a survey official back to Terai to make closer observations of peak 'b', but clouds thwarted all attempts.^[12]

In 1849, Waugh dispatched James Nicolson to the area. Nicolson made two observations from Jirol, 190 km (120 mi) away. Nicolson then took the largest theodolite and headed east, obtaining over 30 observations from five different locations, with the closest being 174 km (108 mi) away from the peak.^[12]

Nicolson retreated to Patna on the Ganges to perform the necessary calculations based on his observations. His raw data gave an average height of 9,200 m (30,200 ft) for peak 'b', but this did not consider light refraction, which distorts heights. The number clearly indicated, however, that peak 'b' was higher than Kangchenjunga. However, Nicolson came down with malaria and was forced to return home, calculations unfinished. Michael Hennessy, one of Waugh's assistants, had begun designating peaks based on roman numerals, with Kangchenjunga named Peak IX, while peak 'b' now became known as Peak XV.^[12]

In 1852, stationed at the survey's headquarters in Dehradun, Radhanath Sikdar, an Indian mathematician and surveyor from Bengal, was the first to identify Everest as the world's highest peak, using trigonometric calculations based on Nicolson's measurements.^[13] An official announcement that Peak XV was the highest was delayed for several years as the calculations were repeatedly verified. Waugh began work on Nicolson's data in 1854, and along with his staff spent almost two years working on the calculations, having to deal with the problems of light refraction, barometric pressure, and temperature over the vast distances of the observations. Finally, in March 1856 he announced his findings in a letter to his deputy in Calcutta. Kangchenjunga was declared to be 28,156 ft (8,582 m), while Peak XV was given the height of 29,002 ft (8,840 m). Waugh concluded that Peak XV was "most probably the highest in the world".^[12] Peak XV (measured in feet) was calculated to be exactly 29,000 ft (8,839.2 m) high, but was publicly declared to be 29,002 ft (8,839.8 m). The arbitrary addition of 2 ft (61 cm) was to avoid the impression that an exact height of 29,000 feet (8,839.2 m) was nothing more than a rounded estimate.^[14]

Naming

With the height now established, what to name the peak was clearly the next challenge. While the survey was anxious to preserve local names if possible (e.g. Kangchenjunga and Dhaulagiri), Waugh argued that he could not find any commonly used local name. Waugh's search for a local name was hampered by Nepal and Tibet's exclusion of foreigners. Many local names existed, including "Deodungha" ("Holy Mountain") in Darjeeling^[15] and the Tibetan "Chomolungma", which appeared on a 1733 map published in Paris by the French geographer D'Anville. In the late 19th century, many European cartographers further believed (incorrectly) that a native name for the mountain was "Gaurisankar",^[16] although this was a result of confusion of Mount Everest with Gauri Sankar, which, when viewed from Kathmandu, stands almost directly in front of Everest.^{[citation needed]}

Waugh argued that with the plethora of local names, it would be difficult to favour one name over all others. So, he decided that Peak XV should be named after George Everest, his predecessor as Surveyor General of India.^[12][17] He wrote:

I was taught by my respected chief and predecessor, Colonel Sir George Everest to assign to every geographical object its true local or native appellation. But here is a mountain, most probably the highest in the world, without any local name that we can discover, whose native appellation, if it has any, will not very likely be ascertained before we are allowed to penetrate into Nepal. In the meantime the privilege as well as the duty devolves on me to assign...a name whereby it may be known among citizens and geographers and become a household word among civilized nations.^[18]

George Everest opposed the name suggested by Waugh and told the Royal Geographical Society in 1857 that Everest could not be written in Hindi nor pronounced by "the native of India". Waugh's proposed name prevailed despite the objections, and in 1865, the Royal Geographical Society officially adopted Mount Everest as the name for the highest mountain in the world.^[12] Interestingly, the modern pronunciation of Everest ˈɛvərɨst, ˈɛvrɨst^[19] is in fact different from Sir George's pronunciation of his surname, which was /ˈiːvrɨst/.^[20]

Aerial view of Mount Everest from the south

The official Tibetan name for Mount Everest is Qomolangma (Tibetan: ཇོ་མོ་གླང་མ, Wylie: Jo mo glang ma, ZYPY: Qomolangma; often spelled Chomolungma; literally "Holy Mother"). The official Chinese name is Zhumulangma (simplified Chinese: 珠穆朗玛峰; traditional Chinese: 珠穆朗瑪峰; pinyin: Zhūmùlǎngmǎ Fēng; literally "Qomolangma Peak") although it is sometimes known as Shengmu Feng (simplified Chinese: 圣母峰; traditional Chinese: 聖母峰; pinyin: Shèngmǔ Fēng; literally "Holy Mother"). In the early 1960s, the Nepalese government coined a Nepali name for Mount Everest, Sagarmāthā (सगरमाथा),^[21] allegedly to supplant the Tibetan name among the locals, which the Nepali government felt was "not acceptable".^{[citation needed]}

In 2002, the Chinese People's Daily newspaper published an article making a case against the use of "Mount Everest" for the mountain in English, insisting that it should be referred to as "Mount Qomolangma", based on the local Tibetan name. The article argued that British colonialists did not "first discover" the mountain, as it had been known to the Tibetans and mapped by the Chinese as "Qomolangma" since at least 1719.^[7]

Measurement

Another aerial view of Mount Everest from the south, with Lhotse in front and Nuptse on the left

The 8,848 m (29,029 ft) height given in this article is officially recognised by Nepal and China,^[22] although Nepal is planning a new survey.^[23]

On 9 October 2005, after several months of measurement and calculation, the Chinese Academy of Sciences and State Bureau of Surveying and Mapping officially announced the height of Everest as 8,844.43 m (29,017.16 ft) with accuracy of ±0.21 m (0.69 ft). They claimed it was the most accurate and precise measurement to date.^[24] This height is based on the actual highest point of rock and not on the snow and ice covering it. The Chinese team also measured a snow/ice depth of 3.5 m (11 ft),^[25] which is in agreement with a net elevation of 8,848 m (29,029 ft). The snow and ice thickness varies over time, making a definitive height of the snow cap impossible to determine.

History

In 1856, Andrew Waugh announced Everest (then known as Peak XV) as 29,002 ft (8,840 m) high, after several years of calculations based on observations made by the Great Trigonometric Survey.

Camps visible on northeast ridge as seen from north base camp area, Tibet on 20 May 2011

The elevation of 8,848 m (29,029 ft) was first determined by an Indian survey in 1955, made closer to the mountain, also using theodolites.^{[citation needed]} It was subsequently reaffirmed by a 1975 Chinese measurement 8,848.13 m (29,029.30 ft).^[25] In both cases the snow cap, not the rock head, was measured. In May 1999 an American Everest Expedition, directed by Bradford Washburn, anchored a GPS unit into the highest bedrock. A rock head elevation of 8,850 m (29,035 ft), and a snow/ice elevation 1 m (3 ft) higher, were obtained via this device.^[26] Although it has not been officially recognized by Nepal,^[27] this figure is widely quoted. Geoid uncertainty casts doubt upon the accuracy claimed by both the 1999 and 2005 surveys.

A detailed photogrammetric map (at a scale of 1:50,000) of the Khumbu region, including the south side of Mount Everest, was made by Erwin Schneider as part of the 1955 International Himalayan Expedition, which also attempted Lhotse. An even more detailed topographic map of the Everest area was made in the late 1980s under the direction of Bradford Washburn, using extensive aerial photography.^[28]

It is thought that the plate tectonics of the area are adding to the height and moving the summit northeastwards. Two accounts suggest the rates of change are 4 mm (0.16 in) per year (upwards) and 3 to 6 mm (0.12 to 0.24 in) per year (northeastwards),^[26][29] but another account mentions more lateral movement (27 mm/1.1 in),^[30] and even shrinkage has been suggested.^[31]

Comparisons

Chimborazo in Ecuador, the furthest point from the earth's centre.

The summit of Everest is the point at which the Earth's surface reaches the greatest distance above sea level. Several other mountains are sometimes claimed as alternative "tallest mountains on Earth". Mauna Kea in Hawaii is tallest when measured from its base;^[32] it rises over 10,200 m (6.3 mi) when measured from its base on the mid-ocean floor, but only attains 4,205 m (13,796 ft) above sea level.

By the same measure of base to summit, Mount McKinley, in Alaska, is also taller than Everest.^[32] Despite its height above sea level of only 6,193.6 m (20,320 ft), Mount McKinley sits atop a sloping plain with elevations from 300 m (980 ft) to 900 m (3,000 ft), yielding a height above base in the range of 5,300 to 5,900 m (17,400 to 19,400 ft); a commonly quoted figure is 5,600 m (18,400 ft).^[33] By comparison, reasonable base elevations for Everest range from 4,200 m (13,800 ft) on the south side to 5,200 m (17,100 ft) on the Tibetan Plateau, yielding a height above base in the range of 3,650 to 4,650 m (11,980 to 15,260 ft).^[28]

The summit of Chimborazo in Ecuador is 2,168 m (7,113 ft) farther from the Earth's centre (6,384.4 km (3,967.1 mi)) than that of Everest (6,382.3 km (3,965.8 mi)), because the Earth bulges at the Equator. For this reason Chimborazo is the closest point to outer space.^[34]

Climbing routes

Southern and northern climbing routes as seen from the International Space Station.

Mt. Everest has two main climbing routes, the southeast ridge from Nepal and the northeast ridge from Tibet, as well as many other less frequently climbed routes.^[35] Of the two main routes, the southeast ridge is technically easier and is the more frequently used route. It was the route used by Edmund Hillary and Tenzing Norgay in 1953 and the first recognized of fifteen routes to the top by 1996.^[35] This was, however, a route decision dictated more by politics than by design as the Chinese border was closed to the western world in the 1950s after the People's Republic of China invaded Tibet.^[36]

View from space showing South Col route and North Col/Ridge route

Most attempts are made during May before the summer monsoon season. As the monsoon season approaches, a change in the jet stream at this time pushes it northward, thereby reducing the average wind speeds high on the mountain.^[37][38] While attempts are sometimes made after the monsoons in September and October, when the jet stream is again temporarily pushed northward, the additional snow deposited by the monsoons and the less stable weather patterns (tail end of the monsoon) makes climbing extremely difficult.

Southeast ridge

The ascent via the southeast ridge begins with a trek to Base Camp at 5,380 m (17,700 ft) on the south side of Everest in Nepal. Expeditions usually fly into Lukla (2,860 m) from Kathmandu and pass through Namche Bazaar. Climbers then hike to Base Camp, which usually takes six to eight days, allowing for proper altitude acclimatization in order to prevent altitude sickness.^[39] Climbing equipment and supplies are carried by yaks, dzopkyos (yak-cow hybrids) and human porters to Base Camp on the Khumbu Glacier. When Hillary and Tenzing climbed Everest in 1953, they started from Kathmandu Valley, as there were no roads further east at that time.

Climbers will spend a couple of weeks in Base Camp, acclimatizing to the altitude. During that time, Sherpas and some expedition climbers will set up ropes and ladders in the treacherous Khumbu Icefall. Seracs, crevasses and shifting blocks of ice make the icefall one of the most dangerous sections of the route. Many climbers and Sherpas have been killed in this section. To reduce the hazard, climbers will usually begin their ascent well before dawn, when the freezing temperatures glue ice blocks in place. Above the icefall is Camp I at 6,065 metres (19,900 ft).

From Camp I, climbers make their way up the Western Cwm to the base of the Lhotse face, where Camp II or Advanced Base Camp (ABC) is established at 6,500 m (21,300 ft). The Western Cwm is a flat, gently rising glacial valley, marked by huge lateral crevasses in the centre, which prevent direct access to the upper reaches of the Cwm. Climbers are forced to cross on the far right near the base of Nuptse to a small passageway known as the "Nuptse corner". The Western Cwm is also called the "Valley of Silence" as the topography of the area generally cuts off wind from the climbing route. The high altitude and a clear, windless day can make the Western Cwm unbearably hot for climbers.^[40]

From ABC, climbers ascend the Lhotse face on fixed ropes up to Camp III, located on a small ledge at 7,470 m (24,500 ft). From there, it is another 500 metres to Camp IV on the South Col at 7,920 m (26,000 ft). From Camp III to Camp IV, climbers are faced with two additional challenges: The Geneva Spur and The Yellow Band. The Geneva Spur is an anvil shaped rib of black rock named by the 1952 Swiss expedition. Fixed ropes assist climbers in scrambling over this snow covered rock band. The Yellow Band is a section of interlayered marble, phyllite, and semischist, which also requires about 100 metres of rope for traversing it.^[40]

On the South Col, climbers enter the death zone. Climbers typically only have a maximum of two or three days they can endure at this altitude for making summit bids. Clear weather and low winds are critical factors in deciding whether to make a summit attempt. If weather does not cooperate within these short few days, climbers are forced to descend, many all the way back down to Base Camp.

A view of Everest southeast ridge base camp. The Khumbu Icefall can be seen in the left. In the center are the remnants of a helicopter that crashed in 2003.

From Camp IV, climbers will begin their summit push around midnight with hopes of reaching the summit (still another 1,000 metres above) within 10 to 12 hours. Climbers will first reach "The Balcony" at 8,400 m (27,600 ft), a small platform where they can rest and gaze at peaks to the south and east in the early light of dawn. Continuing up the ridge, climbers are then faced with a series of imposing rock steps which usually forces them to the east into waist-deep snow, a serious avalanche hazard. At 8,750 m (28,700 ft), a small table-sized dome of ice and snow marks the South Summit.^[40]

From the South Summit, climbers follow the knife-edge southeast ridge along what is known as the "Cornice traverse", where snow clings to intermittent rock. This is the most exposed section of the climb as a misstep to the left would send one 2,400 m (8,000 ft) down the southwest face, while to the immediate right is the 3,050 m (10,000 ft) Kangshung face. At the end of this traverse is an imposing 12 m (40 ft) rock wall called the "Hillary Step" at 8,760 m (28,740 ft).^[40]

Hillary and Tenzing were the first climbers to ascend this step and they did it with primitive ice climbing equipment and ropes. Nowadays, climbers will ascend this step using fixed ropes previously set up by Sherpas. Once above the step, it is a comparatively easy climb to the top on moderately angled snow slopes–though the exposure on the ridge is extreme, especially while traversing large cornices of snow. With increasing numbers of people climbing the mountain in recent years, the Step has frequently become a bottleneck, with climbers forced to wait significant amounts of time for their turn on the ropes, leading to problems in getting climbers efficiently up and down the mountain. After the Hillary Step, climbers also must traverse a loose and rocky section that has a large entanglement of fixed ropes that can be troublesome in bad weather. Climbers will typically spend less than half an hour at the summit to allow time to descend to Camp IV before darkness sets in, to avoid serious problems with afternoon weather, or because supplemental oxygen tanks run out.

Northeast ridge

Mount Everest north face from Rongbuk in Tibet

The northeast ridge route begins from the north side of Everest in Tibet. Expeditions trek to the Rongbuk Glacier, setting up Base Camp at 5,180 m (16,990 ft) on a gravel plain just below the glacier. To reach Camp II, climbers ascend the medial moraine of the east Rongbuk Glacier up to the base of Changtse at around 6,100 m (20,000 ft). Camp III (ABC – Advanced Base Camp) is situated below the North Col at 6,500 m (21,300 ft). To reach Camp IV on the north col, climbers ascend the glacier to the foot of the col where fixed ropes are used to reach the North Col at 7,010 m (23,000 ft). From the North Col, climbers ascend the rocky north ridge to set up Camp V at around 7,775 m (25,500 ft). The route crosses the North Face in a diagonal climb to the base of the Yellow Band reaching the site of Camp VI at 8,230 m (27,000 ft). From Camp VI, climbers will make their final summit push. Climbers face a treacherous traverse from the base of the First Step: 27,890 feet (8,500 m) – 28,000 feet (8,500 m), to the crux of the climb, the Second Step: 28,140 feet (8,580 m) – 28,300 feet. (The Second Step includes a climbing aid called the "Chinese ladder", a metal ladder placed semi-permanently in 1975 by a party of Chinese climbers. It has been almost continuously in place since, and ladders have been used by virtually all climbers on the route.) Once above the Second Step the inconsequential Third Step is clambered over: 28,510 feet (8,690 m) – 28,870 feet (8,800 m). Once above these steps, the summit pyramid is climbed by a snow slope of 50 degrees, to the final summit ridge along which the top is reached.^[41]

See also: the Three Steps

Ascents

Main article: Timeline of climbing Mount Everest

Early expeditions

Rongbuk Monastery in Tibet with the north side of Everest in the background.

In 1885, Clinton Thomas Dent, president of the Alpine Club, suggested that climbing Mount Everest was possible in his book Above the Snow Line.^[42]

The northern approach to the mountain was discovered by George Mallory on the first expedition in 1921. It was an exploratory expedition not equipped for a serious attempt to climb the mountain. With Mallory leading (and thus becoming the first European to set foot on Everest's flanks) they climbed the North Col 7,007 metres (22,989 ft). From there, Mallory espied a route to the top, but the party was unprepared for the great task of climbing any further and descended.

The British returned for a 1922 expedition. George Finch ("The other George") climbed using oxygen for the first time. He ascended at a remarkable speed—950 feet (290 m) per hour, and reached an altitude of 8,320 m (27,300 ft), the first time a human climbed higher than 8,000m. This feat was entirely lost on the British climbing establishment—except for its "unsporting" nature. Mallory and Col. Felix Norton made a second unsuccessful attempt. Mallory was faulted for leading a group down from the North Col which got caught in an avalanche. Mallory was pulled down too, but seven native porters were killed.

The next Expedition was in 1924. The initial attempt by Mallory and Bruce was aborted when weather conditions precluded the establishment of Camp VI. The next attempt was that of Norton and Somervell, who climbed without oxygen and in perfect weather, traversing the North Face into the Great Couloir. Norton managed to reach 8,558 metres (28,077 ft), though he ascended only 100 feet (30 m) or so in the last hour. Mallory rustled up oxygen equipment for a last-ditch effort. He chose young Andrew Irvine as his partner.

On 8 June 1924, George Mallory and Andrew Irvine made an attempt on the summit via the North Col/North Ridge/Northeast Ridge route from which they never returned. On 1 May 1999, the Mallory and Irvine Research Expedition found Mallory's body on the North Face in a snow basin below and to the west of the traditional site of Camp VI. Controversy has raged in the mountaineering community whether one or both of them reached the summit 29 years before the confirmed ascent (and of course, safe descent) of Everest by Sir Edmund Hillary and Tenzing Norgay in 1953.

In 1933, Lady Houston, a British millionairess, funded the Houston Everest Flight of 1933, which saw a formation of aircraft led by the Marquess of Clydesdale fly over the summit in an effort to deploy the British Union Flag at the top.^[43][44][45]

Early expeditions—such as Bruce's in the 1920s and Hugh Ruttledge's two unsuccessful attempts in 1933 and 1936—tried to make an ascent of the mountain from Tibet, via the north face. Access was closed from the north to western expeditions in 1950, after the Chinese asserted control over Tibet. In 1950, Bill Tilman and a small party which included Charles Houston, Oscar Houston and Betsy Cowles undertook an exploratory expedition to Everest through Nepal along the route which has now become the standard approach to Everest from the south.^[46]

The Swiss expedition of 1952, led by Edouard Wyss-Dunant, was granted permission to attempt a climb from Nepal. The expedition established a route through the Khumbu ice fall and ascended to the South Col at an elevation of 7,986 metres (26,201 ft). No attempt at an ascent of Everest was ever under consideration in this case.^[47] Raymond Lambert and Sherpa Tenzing Norgay were able to reach a height of about 8,595 metres (28,199 ft) on the southeast ridge, setting a new climbing altitude record. Tenzing's experience was useful when he was hired to be part of the British expedition in 1953.^[48]

First successful ascent by Tenzing and Hillary

Everest 3D

In 1953, a ninth British expedition, led by John Hunt, returned to Nepal. Hunt selected two climbing pairs to attempt to reach the summit. The first pair (Tom Bourdillon and Charles Evans) came within 100 m (300 feet) of the summit on 26 May 1953, but turned back after running into oxygen problems. As planned, their work in route finding and breaking trail and their caches of extra oxygen were of great aid to the following pair. Two days later, the expedition made its second and final assault on the summit with its second climbing pair, the New Zealander Edmund Hillary and Tenzing Norgay, a Nepali sherpa climber. They reached the summit at 11:30 a.m. local time on 29 May 1953 via the South Col Route. At the time, both acknowledged it as a team effort by the whole expedition, but Tenzing revealed a few years later that Hillary had put his foot on the summit first.^[49] They paused at the summit to take photographs and buried a few sweets and a small cross in the snow before descending.

News of the expedition's success reached London on the morning of Queen Elizabeth II's coronation, 2 June. Returning to Kathmandu a few days later, Hunt (a Briton) and Hillary (a New Zealander) discovered that they had been promptly knighted in the Order of the British Empire, a KBE, for the ascent. Tenzing (a subject of the King of Nepal) was granted the George Medal by the UK. Hunt was ultimately made a life peer in Britain, while Hillary became a founding member of the Order of New Zealand. Hillary and Tenzing are also nationally recognized in Nepal, where annual ceremonies in schools and offices celebrate their accomplishment.^[50]

First ascents without supplemental oxygen and first solo ascent

On 8 May 1978, Reinhold Messner (Italy) and Peter Habeler (Austria) made the first ascent without supplemental oxygen, using the southeast ridge route.^[35][51] On 20 August 1980, Messner reached the summit of the mountain solo for the first time, without supplementary oxygen or support, on the more difficult Northwest route via the North Col to the North Face and the Great Couloir. He climbed for three days entirely alone from his base camp at 6,500 metres (21,300 ft).^[35]

First winter ascent

In 1980, a team from Poland led by Andrzej Zawada, Leszek Cichy, and Krzysztof Wielicki became the first to reach the summit during the winter season.

First ascent by a woman

The first woman to get to the top was Junko Tabei, in 1975, after being rescued from an avalanche by her sherpa.

First ascent from sea level

In 1990 Australian Tim Macartney-Snape became the first person to climb from sea level to the summit.^[52]

1996 disaster

Main article: 1996 Mount Everest disaster

During the 1996 season, 16 people died while climbing on Mount Everest, the highest number of fatalities in a single year in the mountain's history. Eight of them died on 11 May alone. The disaster gained wide publicity and raised questions about the commercialization of climbing Mount Everest.

Journalist Jon Krakauer, on assignment from Outside magazine, was in one of the affected parties, and afterwards published the bestseller Into Thin Air, which related his experience. Anatoli Boukreev, a guide who felt impugned by Krakauer's book, co-authored a rebuttal book called The Climb. The dispute sparked a debate within the climbing community. In May 2004, Kent Moore, a physicist, and John L. Semple, a surgeon, both researchers from the University of Toronto, told New Scientist magazine that an analysis of weather conditions on 11 May suggested that freak weather caused oxygen levels to plunge approximately 14%.^[53][54]

The storm's impact on climbers on the North Ridge of Mount Everest, where several climbers also died, was detailed in a first-hand account by British filmmaker and writer Matt Dickinson in his book The Other Side of Everest. 16-year-old Mark Pfetzer was on the climb and wrote about it in his account, Within Reach: My Everest Story.

2005: Helicopter landing

On 14 May 2005, pilot Didier Delsalle (fr:Didier Delsalle) of France landed a Eurocopter AS350 helicopter on the summit of Mount Everest and took off after about four minutes.^[55] His rotors were continually engaged, constituting a "hover landing", and avoiding the risks of relying on the snow to support the aircraft. He thereby set rotorcraft world records, for highest of both landing and take-off.^[56]

Delsalle had also performed, two days earlier, a take-off from the South Col; some press reports suggested that the report of the summit landing was a misunderstanding of a South Col landing,^[57] but the summit landing was confirmed by the Fédération Aéronautique Internationale.^[58]

2006: David Sharp controversy

Apa Sherpa has reached the summit 21 times

Min Bahadur Sherchan was nearly 77 years old, when he reached the top on his first attempt

Double-amputee climber Mark Inglis revealed in an interview with the press on 23 May 2006, that his climbing party, and many others, had passed a distressed climber, David Sharp, on 15 May, sheltering under a rock overhang 450 metres (1,480 ft) below the summit, without attempting a rescue.^[59] The revelation sparked wide debate on climbing ethics, especially as applied to Everest. The climbers who left him said that the rescue efforts would have been useless and only have caused more deaths. Much of this controversy was captured by the Discovery Channel while filming the television program Everest: Beyond the Limit. A crucial decision affecting the fate of Sharp is shown in the program, where an early returning climber (Max Chaya) is descending and radios to his base camp manager (Russell Brice) that he has found a climber in distress. He is unable to identify Sharp, who had chosen to climb solo without any support and so did not identify himself to other climbers. The base camp manager assumes that Sharp is part of a group that has abandoned him, and informs his climber that there is no chance of him being able to help Sharp. As Sharp's condition deteriorates through the day and other descending climbers pass him, his opportunities for rescue diminish: his legs and feet curl from frostbite, preventing him from walking; the later descending climbers are lower on oxygen and lack the strength to offer aid; time runs out for any Sherpas to return and rescue him. Most importantly, Sharp's decision to forgo all support left him with no margin for recovery.

As this debate raged, on 26 May, Australian climber Lincoln Hall was found alive, after being declared dead the day before. He was found by a party of four climbers (Dan Mazur, Andrew Brash, Myles Osborne and Jangbu Sherpa) who, giving up their own summit attempt, stayed with Hall and descended with him and a party of 11 Sherpas sent up to carry him down. Hall later fully recovered. Similar actions have been recorded since, including on 21 May 2007, when Canadian climber Meagan McGrath initiated the successful high-altitude rescue of Nepali Usha Bista. Recognizing her heroic rescue, Major Meagan McGrath was selected as a 2011 recipient of the Sir Edmund Hillary Foundation of Canada Humanitarian Award, which recognizes a Canadian who has personally or administratively contributed a significant service or act in the Himalayan Region of Nepal.^[60]

Various records

The youngest person to climb Mount Everest was 13-year-old Jordan Romero in May 2010 from the Tibetan side.^[61] His ascent, as part of an apparent "race" to bring younger and younger children to the mountain (shortly after Romero's ascent, Pemba Dorjie Sherpa announced plans to bring his 9 year old son to the summit^[62]), triggered a wave of criticism that prompted Chinese authorities to establish age limits on Mt Everest. At the present time, China no longer grants permits to prospective climbers under 18 or over 60. Nepal sets the minimum age at 16 but has no maximum age.^[63]

Apa Sherpa holds the record for reaching the summit more times than any other person (21 times as of May 2011^[update]).

The fastest ascent via the northeast ridge was accomplished in 2007 by Austrian climber Christian Stangl, who took 16h 42min for the 10 km distance from Camp III (Advanced Base Camp) to the summit, just barely beating Italian Hans Kammerlander's record of 17 hours, accomplished in 1996. Both men climbed alone and without supplementary oxygen. The fastest oxygen-supported ascent over the southeast ridge was Nepalese Pemba Dorjie Sherpa's 2004 climb, taking 8h 10min for the 17-km route from Base Camp to the summit. The fastest ascent without supplementary oxygen via the southeast ridge was accomplished by French Marc Batard, who reached the summit in 22h 30min in 1988.^[64]

The first descent by paraglider was by Jean-Marc Boivin on 26 September 1988^[65] and the first descent by ski was in 2000 by Davo Karnicar.^[66]

The oldest climber to reach Mount Everest's summit is 76-year-old Min Bahadur Sherchan, on 25 May 2008 from the Nepalese side. Sherchan beat the previous record set in 2007 by 71-year-old Katsusuke Yanagisawa.^[67] The oldest climber to reach the summit of Mount Everest from both sides (Nepal and Tibet) of the mountain is 60-year-old Julio Bird, a Puerto Rican cardiologist who reached the summit of Mount Everest from the north side on 17 May 2010.^[68]

The first self-propelled ascent of Mount Everest, the highest point on the earth's surface, starting from the lowest point on the earth's surface – the Dead Sea – was by Phil and Pauline Sanderson in 2006.^[69][70]

Statistics

Ascents of Mount Everest by year through 2010

By the end of the 2010 climbing season, there had been 5,104 ascents to the summit by about 3,142 individuals. 80% of these ascents took place since 2000. In 2007, the record number of 633 ascents has been recorded, by 350 climbers and 253 sherpas. ^[9]

A remarkable illustration of the explosion of popularity of Everest is provided by the numbers of daily ascents. As mentioned below, the 1996 disaster was partly blamed on the number of climbers (33 to 36) attempting to summit on the same day; this was considered unusually high at the time. By comparison, on May 23, 2010, the summit of Mount Everest was reached by 169 climbers.^[9]

Nearly all attempts at the summit are done using one of the two main routes. The traffic seen by each route varies from year to year. In 2005-07, more than half of all climbers elected to use the more challenging, but cheaper northeast route. In 2008, the northeast route was closed by the Chinese government for entire climbing season, and the only people able to reach the summit from the north that year were athletes responsible for carrying the Olympic torch for the 2008 Summer Olympics.^[71] The route was closed to foreigners once again in 2009 in the run-up to the 50th anniversary of the Dalai Lama's exile.^[72] These closures led to declining interest in the north route, and, in 2010, two thirds of the climbers reached the summit from the south. ^[9]

There were 219 fatalities recorded on Mount Everest since the 1922 British Mount Everest Expedition through the end of 2010. 54 of these occurred after 2000: 33 on the northeast ridge, 17 on the southeast ridge, 2 on southwest face, and 2 on north face.^[9]

Cost and commercialization

Climbing Mount Everest is an expensive undertaking. Just the climbing gear required to reach the summit may cost in excess of US$8,000. Most climbers use bottled oxygen, which adds around $3,000 to the cost. The permit to enter the Everest area from the south via Nepal costs $10,000 to $25,000 per person, depending on the size of the team. The ascent typically starts in one of the two base camps near the mountain, both of which are approximately 100 km from Kathmandu and 300 km from Lhasa (the two nearest cities with major airports); transferring one's equipment from the airport to the base camp may add as much as $2,000.

Beyond this point, costs may vary widely. It is technically possible to reach the summit with minimal additional expenses, and there are 'budget' travel agencies which offer logistical support for such trips. However, this is considered difficult and dangerous (as illustrated by the case of David Sharp). Many climbers hire "full service" guide companies, which provide a wide spectrum of services, including acquisition of permits, transportation to/from base camp, food, tents, fixed ropes,^[73] medical assistance while on the mountain, an experienced mountaineer guide, and even personal porters to carry one's backpack and cook one's meals. The cost of such a guide service may range from $40,000 to $80,000 per person.^[74] Since most equipment is moved by sherpas, clients of full-service guide companies can often keep their backpack weights under 10 kg, or hire a sherpa to carry their backpack for them. This can be contrasted with expeditions to less commercialized peaks (for example, climbers attempting Mount McKinley are often expected to carry 30+ kg backpacks and occasionally to tow a sled with 35 kg of gear and food.^[75])

According to Jon Krakauer, the era of commercialization of Everest started in 1985, when the summit was reached by a guided expedition led by David Breashears that included Richard Bass, a wealthy 55 year old businessman and an amateur mountain climber with only 4 years of climbing experience.^[76] By the early 1990's, multiple companies were offering guided tours to the mountain. Rob Hall, the mountaineer who died in the 1996 disaster, had successfully guided 39 clients to the summit prior to that incident.^[77]

The degree of commercialization of Mount Everest is a frequent subject of criticism. Jamling Tenzing Norgay, the son of Tenzing Norgay, said in a 2003 interview that his late father would have been shocked to discover that rich thrill-seekers with no climbing experience were now routinely reaching the summit:

You still have to climb this mountain yourself with your feet. But the spirit of adventure is not there any more. It is lost. There are people going up there who have no idea how to put on crampons. They are climbing because they have paid someone $65,000. It is very selfish. It endangers the lives of others.^[78]

Reinhold Messner concurred in 2004:

You could die in each climb and that meant you were responsible for yourself. We were real mountaineers: careful, aware and even afraid. By climbing mountains we were not learning how big we were. We were finding out how breakable, how weak and how full of fear we are. You can only get this if you expose yourself to high danger. I have always said that a mountain without danger is not a mountain. ... High-altitude alpinism has become tourism and show. These commercial trips to Everest, they are still dangerous. But the guides and organisers tell clients, "Don't worry, it's all organised." The route is prepared by hundreds of Sherpas. Extra oxygen is available in all camps, right up to the summit. People will cook for you and lay out your beds. Clients feel safe and don't care about the risks.^[79]

However, not all opinions on the subject among prominent mountaineers are strictly negative. For example, Edmund Hillary, who went on record saying that he hasn't liked "the commercialization of mountaineering, particularly of Mt. Everest"^[80] and claimed that "Having people pay $65,000 and then be led up the mountain by a couple of experienced guides ... isn't really mountaineering at all",^[81] nevertheless noted that he was pleased by the changes brought to Everest area by the Westerners:

I don’t have any regrets because I worked very hard indeed to improve the condition for the local people. When we first went in there they didn’t have any schools, they didn’t have any medical facilities, all over the years we have established 27 schools, we have two hospitals and a dozen medical clinics and then we've built bridges over wild mountain rivers and put in fresh water pipelines so in cooperation with the Sherpas we've done a lot to benefit them.^[82]

Death zone

Main article: Death zone

At the higher regions of Mount Everest, climbers seeking the summit typically spend substantial time within the "death zone" (altitudes higher than 8,000 m/26,246 ft), and face significant challenges to survival. Temperatures can dip to very low levels, resulting in frostbite of any body part exposed to the air. Since temperatures are so low, snow is well-frozen in certain areas and death or injury by slipping and falling can occur. High winds at these altitudes on Everest are also a potential threat to climbers.

Another significant threat to climbers is low atmospheric pressure. The atmospheric pressure at the top of Everest is about a third of sea level pressure, resulting in the availability of only about a third as much oxygen to breathe.^[83]

Debilitating effects of the death zone are so great that it takes most climbers up to 12 hours to walk the distance of 1.72 km (1.07 miles) from South Col to the summit.^[84] Achieving even this level of performance requires prolonged altitude acclimatization, which takes 40-60 days for a typical expedition. A sea-level dweller exposed to the atmospheric conditions at the altitude above 28,000 feet without acclimatization would likely lose consciousness within 2 to 3 minutes.^[85]

In May 2007, the Caudwell Xtreme Everest undertook a medical study of oxygen levels in human blood at extreme altitude. Over 200 volunteers climbed to Everest Base Camp where various medical tests were performed to examine blood oxygen levels. A small team also performed tests on the way to the summit.^[86]

Even at base camp, the low partial pressure of oxygen had direct effect on blood oxygen saturation levels. At sea level, blood oxygen saturation is generally 98% to 99%. At base camp, blood saturation fell to between 85% and 87%. Blood samples taken at the summit indicated very low oxygen levels in the blood. A side effect of low blood oxygen is a vastly increased breathing rate, often 80–90 breaths per minute as opposed to a more typical 20–30. Exhaustion can occur merely attempting to breathe.^[87]

Lack of oxygen, exhaustion, extreme cold, and climbing hazards all contribute to the death toll. An injured person who cannot walk is in serious trouble, since rescue by helicopter is generally impractical and carrying the person off the mountain is very risky. People who die during the climb are typically left behind. About 150 bodies have never been recovered. It is not uncommon to find corpses near the standard climbing routes.^[88]

Using bottled oxygen

Northern panoramic view of Everest from Tibetan Plateau

Most expeditions use oxygen masks and tanks above 8,000 m (26,246 ft).^[89] Everest can be climbed without supplementary oxygen, but only by the most accomplished mountaineers and at increased risk. Humans do not think clearly with low oxygen, and the combination of extreme weather, low temperatures, and steep slopes often require quick, accurate decisions.

The use of bottled oxygen to ascend Mount Everest has been controversial. It was first used in 1922 by George Finch ("the other George") and Geoffrey Bruce who climbed up to 25,500 ft (7,800 m) at a spectacular speed of 1000 vertical feet per hour. Pinned down by a fierce storm, they escaped death by breathing oxygen from a jury-rigged set-up during the night. The next day they climbed to 26,500 ft (8,100 m) at 900 vf/h--nearly three times as fast as non-oxygen users. Yet the use of oxygen was considered so unsportsmanlike that none of the rest of the Alpine world recognized this high ascent rate.^{[citation needed]} George Mallory himself described the use of such oxygen as unsportsmanlike, but he later concluded that it would be impossible for him to summit without it and consequently used it in his ill-fated attempt in 1924.^[90] When Tenzing and Hillary made the first successful summit in 1953, they used bottled oxygen. For the next twenty-five years, bottled oxygen was considered standard for any successful summit.

Reinhold Messner was the first climber to break the bottled oxygen tradition and in 1978, with Peter Habeler, made the first successful climb without it. Although critics alleged that he sucked mini-bottles of oxygen – a claim that Messner denied – Messner silenced them when he summited the mountain solo, without supplemental oxygen or any porters or climbing partners, on the more difficult northwest route, in 1980. Once the climbing community was satisfied that the mountain could be climbed without supplemental oxygen, many purists then took the next logical step of insisting that's how it should be climbed.^[91]

The aftermath of the 1996 disaster further intensified the debate. Jon Krakauer's Into Thin Air (1997) expressed the author's personal criticisms of the use of bottled oxygen. Krakauer wrote that the use of bottled oxygen allowed otherwise unqualified climbers to attempt to summit, leading to dangerous situations and more deaths. The 10–11 May 1996 disaster was partially caused by the sheer number of climbers (34 on that day) attempting to ascend, causing bottlenecks at the Hillary Step and delaying many climbers, most of whom summitted after the usual 2 p.m. turnaround time. He proposed banning bottled oxygen except for emergency cases, arguing that this would both decrease the growing pollution on Everest—many bottles have accumulated on its slopes—and keep marginally qualified climbers off the mountain.

The 1996 disaster also introduced the issue of the guide's role in using bottled oxygen.^[92] Guide Anatoli Boukreev's decision not to use bottled oxygen was sharply criticized by Jon Krakauer. Boukreev's supporters (who include G. Weston DeWalt, who co-wrote The Climb) state that using bottled oxygen gives a false sense of security.^[93] Krakauer and his supporters point out that, without bottled oxygen, Boukreev could not directly help his clients descend.^[94] They state that Boukreev said that he was going down with client Martin Adams,^[94] but just below the South Summit, Boukreev determines that Adams was doing fine on the descent and so descends at a faster pace, leaving Adams behind. Adams states in The Climb: "For me, it was business as usual, Anatoli's going by, and I had no problems with that."^[95]

2004 photo mosaic the Himalayas with Makalu and Mount Everest from the International Space Station, Expedition 8.

Thefts and other crimes

Some climbers have reported life-threatening thefts from supply caches. Vitor Negrete, the first Brazilian to climb Everest without oxygen and part of David Sharp's party, died during his descent, and theft from his high-altitude camp may have contributed.^[96]

In addition to theft, the 2008 book High Crimes by Michael Kodas describes unethical guides and Sherpas, prostitution and gambling at the Tibet Base Camp, fraud related to the sale of oxygen bottles, and climbers collecting donations under the pretense of removing trash from the mountain.^[97][98]

Flora and fauna

Euophrys omnisuperstes, a minute black jumping spider, has been found at elevations as high as 6,700 metres (22,000 ft), possibly making it the highest confirmed non-microscopic permanent resident on Earth. It lurks in crevices and may feed on frozen insects that have been blown there by the wind. It should be noted that there is a high likelihood of microscopic life at even higher altitudes.^[99] Birds, such as the Bar-headed Goose, have been seen flying at the higher altitudes of the mountain, while others, such as the Chough, have been spotted as high as the South Col at 7,920 metres (25,980 ft)^[100] scavenging on food, or even corpses, left by prior climbing expeditions.

Geology

The last rays of sunlight on Mount Everest on 5 May 2007

Geologists have subdivided the rocks comprising Mount Everest into three units called "formations".^[101][102] Each formation is separated from the other by low-angle faults, called “detachments”, along which they have been thrust over each other. From the summit of Mount Everest to its base these rock units are the Qomolangma Formation, the North Col Formation, and the Rongbuk Formation.

From its summit to the top of the Yellow Band, about 8,600 m (28,000 ft) above sea level, the top of Mount Everest consists of the Qomolangma Formation, which has also been designated as either the Everest Formation or Jolmo Lungama Formation. It consists of grayish to dark gray or white, parallel laminated and bedded, Ordovician limestone inter layered with subordinate beds of recrystallized dolomite with argillaceous laminae and siltstone. Gansser first reported finding microscopic fragments of crinoids in this limestone.^[103] Later petrographic analysis of samples of the limestone from near the summit revealed them to be composed of carbonate pellets and finely fragmented remains of trilobites, crinoids, and ostracods. Other samples were so badly sheared and recrystallized that their original constituents could not be determined. A thick, white-weathering thrombolite bed that is 60 m (200 ft) thick comprises the foot of the "Third Step," and base of the summit pyramid of Everest. This bed, which crops out starting about 70 m (300 ft) below the summit of Mount Everest, consists of sediments trapped, bound, and cemented by the biofilms of microorganisms, especially cyanobacteria, in shallow marine waters. The Qomolangma Formation is broken up by several high-angle faults that terminate at the low angle thrust fault, the Qomolangma Detachment. This detachment separates it from the underlying Yellow Band. The lower five metres of the Qomolangma Formation overlying this detachment are very highly deformed.^{[101][102][104]}

The bulk of Mount Everest, between 7,000 and 8,600 m (23,000 and 28,200 ft), consists of the North Col Formation, of which the Yellow Band forms its upper part between 8,200 to 8,600 m (26,900 to 28,200 ft). The Yellow Band consists of intercalated beds of Middle Cambrian diopside-epidote-bearing marble, which weathers a distinctive yellowish brown, and muscovite-biotite phyllite and semischist. Petrographic analysis of marble collected from about 8,300 m (27,200 ft) found it to consist as much as five percent of the ghosts of recrystallized crinoid ossicles. The upper five metres of the Yellow Band lying adjacent to the Qomolangma Detachment is badly deformed. A 5–40 cm (2–16 in) thick fault breccia separates it from the overlying Qomolangma Formation.^{[101][102][104]}

The remainder of the North Col Formation, exposed between 7,000 to 8,200 m (23,000 to 26,900 ft) on Mount Everest, consists of interlayered and deformed schist, phyllite, and minor marble. Between 7,600 and 8,200 m (24,900 and 26,900 ft), the North Col Formation consists chiefly of biotite-quartz phyllite and chlorite-biotite phyllite intercalated with minor amounts of biotite-sericite-quartz schist. Between 7,000 and 7,600 m (23,000 and 24,900 ft), the lower part of the North Col Formation consists of biotite-quartz schist intercalated with epidote-quartz schist, biotite-calcite-quartz schist, and thin layers of quartzose marble. These metamorphic rocks appear to be the result of the metamorphism of Middle to Early Cambrian deep sea flysch composed of interbedded, mudstone, shale, clayey sandstone, calcareous sandstone, graywacke, and sandy limestone. The base of the North Col Formation is a regional thrust fault called the "Lhotse detachment".^{[101][102][104]}

Below 7,000 m (23,000 ft), the Rongbuk Formation underlies the North Col Formation and forms the base of Mount Everest. It consists of sillminite-K-feldspar grade schist and gneiss intruded by numerous sills and dikes of leucogranite ranging in thickness from 1 cm to 1,500 m (0.4 in to 4,900 ft).^[102][105]

Environment

Besides rubbish, the degradation on Himalayan peaks and other issues concerned Apa Sherpa. He said when he first started climbing Everest, the trail to the summit was covered with ice and snow. But it is now dotted with bare rocks. The melting ice has also exposed deep crevasses, making expeditions more dangerous.^[106]

See also

• Earth Day 20 International Peace Climb
• Everest Base Camp
• Geology of the Himalaya
• Kangshung Face, Mount Everest
• List of deaths on eight-thousanders
• Sagarmatha National Park
• Timeline of climbing Mount Everest

References

1. ^ Based on elevation of snow cap, not rock head. For more details, see Measurement.
2. ^ The position of the summit of Everest on the international border is clearly shown on detailed topographic mapping, including official Nepalese mapping.
3. ^ The WGS84 coordinates given here were calculated using detailed topographic mapping and are in agreement with adventurestats. They are unlikely to be in error by more than 2". Coordinates showing Everest to be more than a minute further east that appeared on this page until recently, and still appear in Wikipedia in several other languages, are incorrect.
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32. ^ ^{a b} The "base" of a mountain is a problematic notion in general with no universally accepted definition. However for a peak rising out of relatively flat terrain, such as Mauna Kea or Denali, an approximate height above "base" can be calculated. For Everest the situation is more complicated, since it only rises above relatively flat terrain on its north (Tibetan Plateau) side. Hence the concept of "base" has even less meaning for Everest than for Mauna Kea or Denali, and the range of numbers for "height above base" is wider. In general, comparisons based on "height above base" are somewhat suspect.
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50. ^ "Tribute to Sir Ed Hillary From Nepal". http://www.alpinist.com/doc/web07-08w/rb-ang-tshering-sherpa-hillary-tribute. Retrieved 20 September 2010. 
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53. ^ "The day the sky fell on Everest". New Scientist (2449): 15. 2004-05-29. Archived from the original on 2007-07-03. http://web.archive.org/web/20070703183045/http://www.newscientisttech.com/article/mg18224492.200-the-day-the-sky-fell-on-everest.html. Retrieved 2006-12-11. 
54. ^ Peplow, Mark (2004-05-25). "High winds suck oxygen from Everest Predicting pressure lows could protect climbers.". BioEd Online. http://www.bioedonline.org/news/news.cfm?art=986. Retrieved 2006-12-11. "Moore explains that these jet streaks can drag a huge draught of air up the side of the mountain, lowering the air pressure. He calculates that this typically reduces the partial pressure of oxygen in the air by about 6%, which translates to a 14% reduction in oxygen uptake for the climbers. Air at that altitude already contains only one third as much oxygen as sea-level air." 
55. ^ "Landing on Air". National Geographic Adventure. 2005-09-01. http://www.nationalgeographic.com/adventure/0509/whats_new/helicopter_everest.html. Retrieved 2009-06-24. 
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58. ^ Rotorcraft World Records
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64. ^ "Everest 2008: Marc Batard back for speed record attempt on north side". MountEverest.net. 2008-01-21. http://www.mounteverest.net/news.php?id=16931. 
65. ^ "A view from the top of the world ", BBC News, 15 February 2007, retrieved 6 October 2010
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68. ^ Terry Rindfleisch (2010-06-06), La Crosse doctor oldest to climb both sides of Mt. Everest, La Crosse Tribune, http://lacrossetribune.com/news/local/article_a2f3a430-7124-11df-a64f-001cc4c002e0.html?mode=story, retrieved 2010-06-06 
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72. ^ "China closes Tibetan side of Everest to climbers ahead of anniversary of Dalai Lama's exile". http://www.telegraph.co.uk/news/worldnews/asia/china/4806464/China-closes-Tibetan-side-of-Everest-to-climbers-ahead-of-anniversary-of-Dalai-Lamas-exile.html. 
73. ^ "Fixed ropes". http://www.mounteverest.net/expguide/ropes.htm. 
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75. ^ "The Physical Demands of Climbing Denali". http://www.aai.cc/pdf_download/denali_phycond.pdf. 
76. ^ "Conquers Mt. Everest to Fulfill Dream : Millionaire First to Climb Summits of All Continents". Los Angeles Times. 1985. http://articles.latimes.com/1985-05-02/news/mn-20109_1_climbed-mt-everest. 
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79. ^ "Home on the range". http://observer.guardian.co.uk/osm/story/0,,1315445,00.html. 
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106. ^ More Dangerous Climbing

Further reading

• Astill, Tony. Mount Everest : The Reconnaissance 1935, The Author, 2005.
• American Alpine Journal, 2005, p. 393.
• Hillary, Edmund, High Adventure, London, Hodder & Stoughton, 1953.
• Irving, R. L. G., Ten Great Mountains. London, J. M. Dent & Sons, 1940. (The climbing history up to 1939 of Snowdon, Ben Nevis, Ushba, Mount Logan, Everest, Nanga Parbat, Kanchenjunga, the Matterhorn, Aoraki/Mount Cook and Mont Blanc.)
• Krakauer, Jon, Into Thin Air: A Personal Account of the Mt. Everest Disaster, New York, Villard, 1997, ISBN 0-679-45752-6.
• Messner, Reinhold. The Crystal Horizon : Everest--the first solo ascent, Seattle, The Mountaineers, 1989, ISBN 0898862078, ISBN 0898865743 (pbk).
• Murray, W. H., The Story of Everest, 1921–1952, London, J. M. Dent & Sons, 1953.
• Newby, Eric, A Short Walk in the Hindu Kush, London, Hodder & Stoughton, 1958.
• Norgay, Tenzing with Ullman, Ramsey James, Tiger of the Snows, New York, Putnam, 1955.
• Tilman, H. W., Nepal Himalaya, Cambridge University Press, 1952.

External links

• National Geographic site on Mt. Everest
• NOVA site on Mt. Everest
• Royal Geographical Society site on Mt. Everest
• North *South
• Interactive climb of Everest from Discovery Channel
• Mount Everest on Summitpost
• Full list of all ascents of Everest up to and including 2008 (in pdf format)
• Summits and deaths per year
• The Everest Trek guidebook
• Expeditions tracking on line in the different routes of ascent of Mount Everest
• Mount Everest panorama, Mount Everest interactive panorama (Quicktime format), Virtual panoramas