"Everest" redirects here. For other uses see Everest (disambiguation). Mount Everest Nepali: Chomolungma Qomolangma Everest from Kala Patthar in Nepal Elevation 8848 m (29029 ft)1 Ranked 1st Prominence 8848 m (29029 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 Xigaz Prefecture Tibet Autonomous Region People's Republic of China2 Range Mahalangur Himal Himalayas Coordinates 275917N 865531E / 27.98806N 86.92528E / 27.98806; 86.92528Coordinates: 275917N 865531E / 27.98806N 86.92528E / 27.98806; 86.925283 Climbing First ascent 29 May 1953 Edmund Hillary Tenzing Norgay Easiest route South Col (Nepal)

Mount Everest (Tibetan: Jomolungma "Holy Mother"; Chinese: Mandarin: Zhmlngm Fng "Jomolungma Peak"; Nepali: Sagarmth) is the world's highest mountain at 8848 metres (29029 ft) above sea level. Everest is in the Mahalangur section of the Himalaya on the Nepal-China (Tibet) border. Its massif includes neighboring peaks Lhotse (8516m) Nuptse (7855m) and Changtse (7580m).

In 1856 the Great Trigonometric Survey of British India established the first published height of Everest then known as Peak XV at 29002 ft (8840 m). In 1865 Everest was given its official English name by the Royal Geographical Society upon recommendation of Andrew Waugh the British Surveyor General of India at the time who named it after his predecessor in the post and former chief Sir George Everest. Chomolungma had been in common use by Tibetans for centuries but Waugh was unable to propose an established local name because Nepal and Tibet were closed to foreigners.

The highest mountain in the world attracts many well-experienced mountaineers as well as novice climbers who are willing to pay substantial sums to professional mountain guides to complete a successful climb. The mountain while not posing substantial technical climbing difficulty on the standard route (other eight-thousanders such as K2 or Nanga Parbat are much more difficult) still has many inherent dangers such as altitude sickness weather and wind.

By the end of the 2008 climbing season there had been 4102 ascents to the summit by about 2700 individuals.4 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$25000 per person.5 By the end of 2009 Everest had claimed 216 lives4 including eight who perished during a 1996 storm high on the mountain. Conditions are so difficult in the death zonealtitudes higher than 8000 metres (26000 ft)that most corpses have been left where they fell. Some of them are visible from standard climbing routes.6 Contents 1 Identifying the highest mountain 2 Naming 3 Measurement 3.1 Comparisons 4 Climbing routes 4.1 Southeast ridge 4.2 Northeast ridge 5 Ascents 5.1 Early expeditions 5.2 First successful ascent by Tenzing and Hillary 5.3 First ascents without supplemental oxygen and first solo ascent 5.4 First winter ascent 5.5 1996 disaster 5.6 2005: Helicopter landing 5.7 2006: David Sharp controversy 5.8 Various records 6 Death zone 7 Using bottled oxygen 8 Thefts and other crimes 9 Flora and fauna 10 Geology 11 Environment 12 See also 13 References 14 Further reading 15 External links Identifying the highest mountain Location on Earth Mount Everest relief map

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 (1100 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.7

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 malariathree survey officers died from malaria while two others had to retire owing to failing health.7

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.7

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.7

Nicolson retreated to Patna on the Ganges to perform the necessary calculations based on his observations. His raw data gave an average height of 9200 m (30200 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.7 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.8 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 Kolkata. Kangchenjunga was declared to be 28156 ft (8582 m) while Peak XV was given the height of 29002 ft (8840 m). Waugh concluded that Peak XV was "most probably the highest in the world".7 Peak XV (measured in feet) was calculated to be exactly 29000 ft (8839.2 m) high but was publicly declared to be 29002 ft (8839.8 m). The arbitrary addition of 2 ft (61 cm) was to avoid the impression that an exact height of 29000 feet (8839.2 m) was nothing more than a rounded estimate.9 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 Darjeeling10 and the Tibetan "Jomolungma" () which appeared as "Chomolungma" 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"11 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.712 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.13 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.7 Interestingly the modern pronunciation of Everest vrst vrst14 is in fact different from Sir George's pronunciation of his surname which was /ivrst/.15 Aerial view of Mount Everest from the south The modern Tibetan name for Mount Everest is (Wylie: Jomolungma; also transliterated Chomolungma in the West and Qomolangma in China) meaning "Holy Mother". The official Chinese name is Zhmlngm Fng (simplified Chinese: ; traditional Chinese: ) "Jomolungma Peak" although it is sometimes known as Shngm Fng (simplified Chinese: ; traditional Chinese: ) the Chinese for "Holy Mother". In the early 1960s the Nepalese government gave Mount Everest the official name Sagarmth ()16 although this name had not previously been used. The local inhabitants knew the mountain as Jomolungma. The mountain was not previously named in Nepali.citation needed The government set out to find a Nepalese name for the mountain because the government felt the Tibetan name Jomolungma was not acceptable.citation needed In 2002 the Chinese People's Daily newspaper published an article making a case against the continued use of the English name for the mountain in the Western world insisting that it should be referred to by its Tibetan name. The newspaper argued that the Chinese use of the Tibetan name preceded the English one as "Mount Qomolangma" was marked on a Chinese map more than 280 years ago.17 Measurement Another aerial view of Mount Everest from the south with Lhotse in front and Nuptse on the left In 1856 Andrew Waugh announced Everest (then known as Peak XV) as 29002 ft (8840 m) high after several years of calculations based on observations made by the Great Trigonometric Survey. The 8848 m (29029 ft) height given in this article is officially recognised by Nepal and China.18 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 8844.43 m (29017.16 ft) with accuracy of 0.21 m (0.69 ft). They claimed it was the most accurate and precise measurement to date.19 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)20 which is in agreement with a net elevation of 8848 m (29029 ft). The snow and ice thickness varies over time making a definitive height of the snow cap impossible to determine. Camps visible on northeast ridge as seen from north base camp area Tibet on May 20 2011 The elevation of 8848 m (29029 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 8848.13 m (29029.30 ft).20 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 8850 m (29035 ft) and a snow/ice elevation 1 m (3 ft) higher were obtained via this device.21 Although it has not been officially recognized by Nepal22 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 1:50000) 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.23 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)2124 but another account mentions more lateral movement (27 mm/1.1 in)25 and even shrinkage has been suggested.26 Comparisons 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;27 it rises over 10200 m (6.3 mi) when measured from its base on the mid-ocean floor but only attains 4205 m (13796 ft) above sea level. By the same measure of base27 to summit Mount McKinley in Alaska is also taller than Everest. Despite its height above sea level of only 6193.6 m (20320 ft) Mount McKinley sits atop a sloping plain with elevations from 300 m (980 ft) to 900 m (3000 ft) yielding a height above base in the range of 5300 to 5900 m (17400 to 19400 ft); a commonly quoted figure is 5600 m (18400 ft).28 By comparison reasonable base elevations for Everest range from 4200 m (13800 ft) on the south side to 5200 m (17100 ft) on the Tibetan Plateau yielding a height above base in the range of 3650 to 4650 m (11980 to 15260 ft).23 The summit of Chimborazo in Ecuador is 2168 m (7113 ft) farther from the Earth's centre (6384.4 km (3967.1 mi)) than that of Everest (6382.3 km (3965.8 mi)) because the Earth bulges at the Equator. However Chimborazo attains a height of only 6267 m (20561 ft) above sea level and by this criterion it is not even the highest peak of the Andes. 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.29 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 1996.29 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.30 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.3132 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 5380 m (17700 ft) on the south side of Everest in Nepal. Expeditions usually fly into Lukla (2860 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.33 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 6065 metres (19900 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 6500 m (21300 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.34 From ABC climbers ascend the Lhotse face on fixed ropes up to Camp III located on a small ledge at 7470 m (24500 ft). From there it is another 500 metres to Camp IV on the South Col at 7920 m (26000 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.34 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 1000 metres above) within 10 to 12 hours. Climbers will first reach "The Balcony" at 8400 m (27600 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 8750 m (28700 ft) a small table-sized dome of ice and snow marks the South Summit.34 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 2400 m (8000 ft) down the southwest face while to the immediate right is the 3050 m (10000 ft) Kangshung face. At the end of this traverse is an imposing 12 m (40 ft) rock wall called the "Hillary Step" at 8760 m (28740 ft).34 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 slopesthough 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 a half-hour at the summit to allow time to descend to Camp IV before darkness sets in afternoon weather becomes a serious problem or 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 5180 m (16990 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 6100 m (20000 ft). Camp III (ABC Advanced Base Camp) is situated below the North Col at 6500 m (21300 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 7010 m (23000 ft). From the North Col climbers ascend the rocky north ridge to set up Camp V at around 7775 m (25500 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 8230 m (27000 ft). From Camp VI climbers will make their final summit push. Climbers face a treacherous traverse from the base of the First Step: 27890 feet (8500 m) 28000 feet (8500 m) to the crux of the climb the Second Step: 28140 feet (8580 m) 28300 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: 28510 feet (8690 m) 28870 feet (8800 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.35 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.36 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 7007 metres (22989 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 speed950 feet (290 m) per hour and reached an altitude of 8320 m (27300 ft) the first time a human climbed higher than 8000m. This feat was entirely lost on the British climbing establishmentexcept 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 8558 metres (28077 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 the 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 millionaire ex-showgirl 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.373839 Early expeditionssuch as Bruce's in the 1920s and Hugh Ruttledge's two unsuccessful attempts in 1933 and 1936tried 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.40 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 7986 metres (26201 ft). No attempt at an ascent of Everest was ever under consideration in this case.41 Raymond Lambert and Sherpa Tenzing Norgay were able to reach a height of about 8595 metres (28199 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 1953.42 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.43 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 June 2. 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.44 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.2945 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 6500 metres (21300 ft).29 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. 1996 disaster Main article: 1996 Mount Everest disaster During the 1996 season 15 people died while climbing on Mount Everest making it the deadliest 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%.4647 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 of France landed a Eurocopter AS 350 B3 helicopter on the summit of Mount Everest48 (without any witness) and took off after about four minutes. (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 (de facto) and take-off (formally).49 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.50 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 200651 that his climbing party and many others had passed a distressed climber David Sharp on 15 May sheltering under a rock overhang 450 metres (1480 ft) below the summit without attempting a rescue. 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. Various records The youngest person to climb Mount Everest was 13-year-old Jordan Romero in May 2010.52 Apa Sherpa holds the record for reaching the summit more times than any other person (21 times as of May 2011update). The fastest ascent over the northeast ridge was accomplished in 2007 by Austrian climber Christian Stangl who needed 16h 42min for the 10 km distance from Camp III 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 using 8h 10min for the 17 km route. The fastest ascent without supplementary oxygen over the southeast ridge was accomplished by French Marc Batard who reached the summit in 22h 30min in 1988.53 The first descent by paraglider was by Jean-Marc Boivin on 26 September 198854 and the first descent by ski was in 2000 by Davo Karnicar.55 The oldest climber to reach Mt. Everest's summit is 76-year-old Min Bahadur Sherchan who did so 25 May 2008 from the Nepal side. Sherchan beat the previous record set in 2007 by 71 year old Katsusuke Yanagisawa.56 The oldest climber to summit Mt. 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 Mt. Everest from the north side on May 17 2010.57 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 8000 m/26246 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.58 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.59 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 8090 breaths per minute as opposed to a more typical 2030. Exhaustion can occur merely attempting to breathe.60 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.61 Using bottled oxygen Northern panoramic view of Everest from Tibetan Plateau Most expeditions use oxygen masks and tanks above 8000 m (26246 ft).62 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 25500 ft (7800 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 26500 ft (8100 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 1924.63 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.64 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 1011 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 Everestmany bottles have accumulated on its slopesand keep marginally qualified climbers off the mountain. The 1996 disaster also introduced the issue of the guide's role in using bottled oxygen.65 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.66 Krakauer and his supporters point out that without bottled oxygen Boukreev could not directly help his clients descend.67 They state that Boukreev said that he was going down with client Martin Adams67 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."68 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.69 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.7071 Flora and fauna Euophrys omnisuperstes a minute black jumping spider has been found at elevations as high as 6700 metres (22000 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.72 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 (7920 m)73 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".7475 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 8600 m (28000 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.76 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.747577 The bulk of Mount Everest between 7000 and 8600 m (23000 and 28200 ft) consists of the North Col Formation of which the Yellow Band forms its upper part between 8200 to 8600 m (26900 to 28200 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 8300 m (27200 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 540 cm (216 in) thick fault breccia separates it from the overlying Qomolangma Formation.747577 The remainder of the North Col Formation exposed between 7000 to 8200 m (23000 to 26900 ft) on Mount Everest consists of interlayered and deformed schist phyllite and minor marble. Between 7600 and 8200 m (24900 and 26900 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 7000 and 7600 m (23000 and 24900 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".747577 Below 7000 m (23000 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 1500 m (0.4 in to 4900 ft).7578 Environment Besides rubbish the degradation on Himalayan peaks because of global warming and other issues concerned Apa Sherpa. "When I 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."79 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 Based on elevation of snow cap not rock head. For more details see Measurement. The position of the summit of Everest on the international border is clearly shown on detailed topographic mapping including official Nepalese mapping. 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. a b "Full list of all ascents of Everest up to and including 2008 (in pdf format)". 8000ers.com. 2008-02-13. http://www.8000ers.com/cms/content/view/52/185/. Retrieved 2010-08-22.  "National Geographic Adventure Magazine: Ask AdventureTips". National Geographic Society. May 2005. http://www.nationalgeographic.com/adventure/0305/experteverest.html. Retrieved 2008-01-23.  Bryant Charles W.. "Are there dead bodies on Mount Everest". Adventure.howstuffworks.com. http://adventure.howstuffworks.com/dead-everest1.htm. Retrieved 2010-08-22.  a b c d e f g h Peter Gillman ed (1993). Everest The Best Writing and Pictures from Seventy Years of Human Endeavour. Little Brown and Company. pp. 1013. ISBN 9780-316-90489-6.  "The man who 'discovered' Everest". BBC News. 2003-10-20. http://news.bbc.co.uk/2/hi/southasia/3193576.stm. Retrieved 2008-04-11.  Letters to the Editor The American Statistician Vol. 36 No. 1 (Feb. 1982) pp. 6467 JSTOR "Mt. Everest 1857". harappa.com. http://www.harappa.com/engr/darjeeling.html#everest. Retrieved 2008-01-23.  L. A. Waddell "The Environs and Native Names of Mount Everest" The Geographical Journal Vol. 12 No. 6 (Dec. 1898) pp. 564569. Available at JSTOR. (India and China). The Times (London). Sat 4 October 1856. Issue 22490 col B p. 8. "Papers relating to the Himalaya and Mount Everest" Proceedings of the Royal Geographical Society of London no.IX pp.345351 AprilMay 1857. "Mount Everest." Dictionary.com Unabridged (v 1.1). Random House Inc. 22 Jul. 2009. <Dictionary.com http://dictionary.reference.com/browse/Mount Everest>. Claypole Jonty (Director); Kunzru Hari (Presenter). (2003). Mapping Everest. TV Documentary. London: BBC Television. http://www.bbc.co.uk/programmes/b0074phg.  Unsworth Walt (2000). Everest The Mountaineering History (3rd ed.). Bton Wicks. p. 584. ISBN 978-1898573401.  "No Longer Everest but Mount Qomolangma". People's Daily Online. 2002-11-20. http://english.people.com.cn/200211/19/eng20021119107017.shtml. Retrieved 2005-06-09.  "BBC News". BBC News. 2010-04-08. http://news.bbc.co.uk/1/hi/world/southasia/8608913.stm. Retrieved 2010-08-22.  "China says Mount Qomolangma stands at 8844.43". Xinhua online. Xinhua News Agency. 2005-10-09. http://news.xinhuanet.com/english/2005-10/09/content3597013.htm. Retrieved 2007-04-01.  a b "Everest not as tall as thought". News in Science. Australian Broadcasting Corporation. 2005-10-05. http://www.abc.net.au/science/news/enviro/EnviroRepublish1478658.htm. Retrieved 2007-04-01.  a b "Elevation of Mount Everest newly defined". Swiss Foundation for Alpine Research. 1999-11-12. Archived from the original on 2007-01-03. http://web.archive.org/web/20070103165811/http://www.alpineresearch.ch/alpine/en/presse1.html. Retrieved 2007-04-01.  "Country Profile". Government of Nepal. 2001. Archived from the original on March 14 2007. http://web.archive.org/web/20070314011131/http://www.nepalgov.gov.np/countryprofile.php. Retrieved 2007-04-01.  a b Mount Everest (1:50000 scale map) prepared under the direction of Bradford Washburn for the Boston Museum of Science the Swiss Foundation for Alpine Research and the National Geographic Society 1991 ISBN 3-85515-105-9 "Roof of the World". National Geographic Society. 1999. http://www.nationalgeographic.com/features/99/everest/roofcontent.html. Retrieved 2007-04-01.  "Everest: Plate Tectonics". Museum of Science. 1998. http://www.mos.org/Everest/exhibit/platetectonics.htm. Retrieved 2007-04-01. dead link Now hosted at the Internet Archive at the Wayback Machine (archived May 17 2006).dead link "China fears Everest is shrinking". BBC News. 2005-01-25. http://news.bbc.co.uk/1/hi/world/asia-pacific/4204539.stm. Retrieved 2007-04-01.  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. "NOVA Online: Surviving Denali The Mission". NOVA. Public Broadcasting Corporation. 2000. http://www.pbs.org/wgbh/nova/denali/expedition/mission.html. Retrieved 2007-06-07.  a b c d "Ascent Routes on Everest". EverestHistory.com. http://www.everesthistory.com/routes.htm. Retrieved 2008-01-23.  Thompson Kalee (2003-04-02). "Everest Time Line: 80 Years of Triumph and Tragedy". National Geographic Society. http://news.nationalgeographic.com//news/2003/04/0401030401everesttimeline.html. Retrieved 2008-03-28.  "Climbing Mount Everest". The New York Times. 1997-05-19. http://query.nytimes.com/gst/fullpage.htmlres9E01EFDD1E38F93AA25756C0A961958260. Retrieved 2008-10-24.  Team Everest 03. "Mt. Everest Information". http://www.teameverest03.org/everestinfo/index.html. Retrieved 2008-10-24.  Muza SR; Fulco CS; Cymerman A (2004). "Altitude Acclimatization Guide.". US Army Research Inst. Of Environmental Medicine Thermal and Mountain Medicine Division Technical Report (USARIEM-TN-04-05). http://archive.rubicon-foundation.org/7616. Retrieved 2009-03-05.  a b c d "The Way to the Summit". NOVA Online. Public Broadcasting Corporation. 2000. http://www.pbs.org/wgbh/nova/everest/climb/waytosummitsou.html. Retrieved 2008-03-28.  "The Way to the Summit (North)". NOVA Online. Public Broadcasting Corporation. 2000. http://www.pbs.org/wgbh/nova/everest/climb/waytosummitnor.html. Retrieved 2008-03-28.  William Buxton (2008-04-12). "From First Sight to Summit: A Guide to the Literature on Everest up to the 1953 Ascent" (PDF). http://www.billbuxton.com/everest.pdf. Retrieved 2008-01-23.  "Aeroplane expeditions to Everest". flymicro.com. http://www.flymicro.com/everest/index.cfmpagedocs%2FHistory%2FAeroplanes.htm.  "Wings Over Everest 2003". K2 News. 2002. http://www.k2news.com/wingsover.htm.  "Flying Over World's Highest Peak" Popular Science May 1933 "Everest History Time Line". Everest History.com. 2003. http://www.everesthistory.com/time3.htm.  "Excerpt from: Swiss Foundation for Alpine Research 1939 to 1970. Published in Zurich in 1972". http://www.sfar-evev06.ch/en/expeditions/everest52f.html. Retrieved 9 January 2010.  "Tenzing Norgay GM". http://imagingeverest.rgs.org/Concepts/VirtualEverest/-116.html. Retrieved 2007-06-21.  Tenzing Norgay and James Ramsey Ullman Man of Everest (1955 also published as Tiger of the Snows) "Tribute to Sir Ed Hillary From Nepal". http://www.alpinist.com/doc/web07-08w/rb-ang-tshering-sherpa-hillary-tribute. Retrieved 20 September 2010.  "Everest First without oxygen". NOVA Online. PBS. 2000. http://www.pbs.org/wgbh/nova/everest/history/firstwoo2.html. Retrieved 2008-03-28.  "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.  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.cfmart986. 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."  "Landing on Air". National Geographic Adventure. 2005-09-01. http://www.nationalgeographic.com/adventure/0509/whatsnew/helicoptereverest.html. Retrieved 2009-06-24.  Federation Aeronautique Internationale records page. (Search for "Everest" on that page). "French Everest Mystery Chopper's Utopia summit". MountEverest.net. 2005-05-27. http://www.mounteverest.net/story/FrenchEverestMysteryChoppersUtopiasummit-VIDEOMay272005.shtml.  "Everest climber defends leaving dying Briton". Australian Broadcasting Corporation. 2006-05-23. http://www.abc.net.au/news/newsitems/200605/s1645603.htm.  "Everest K2 News Explorersweb the pioneers checkpoint". Explorersweb.com. 2010-05-21. http://explorersweb.com/everestk2/news.phpid19380. Retrieved 2010-08-22.  "Everest 2008: Marc Batard back for speed record attempt on north side". MountEverest.net. 2008-01-21. http://www.mounteverest.net/news.phpid16931.  "A view from the top of the world " BBC News 15 February 2007 retrieved 6 October 2010 "Everest only complete ski descent flashback: Davo Karnicars non-stop ride". June 28 2006. http://www.mounteverest.net/news.phpid10110. Retrieved 30 November 2009.  "76-year-old breaks Everest record". Associated Press. CNN. 2008-05-25. Archived from the original on June 9 2008. http://web.archive.org/web/20080609232633/http://www.cnn.com/2008/WORLD/asiapcf/05/25/everest.old.ap/index.html. Retrieved 2008-10-24.  Terry Rindfleisch (2010-06-06) La Crosse doctor oldest to climb both sides of Mt. Everest La Crosse Tribune http://lacrossetribune.com/news/local/articlea2f3a430-7124-11df-a64f-001cc4c002e0.htmlmodestory retrieved 2010-06-06  "Online high altitude oxygen calculator". altitude.org. http://www.altitude.org/calculators/airpressure.php. Retrieved 2007-08-15.  "Everest 2007". Caudwell Xtreme Everest 2007. http://www.xtreme-everest.co.uk/newsdetail.phparticle196. Retrieved 2008-03-28.  "Altitude physiology". altitude.org. http://www.altitude.org/oxygenlevels.php. Retrieved 2010-07-06.  "The deadly business of climbing Everest". Melbourne: The Age. 2006-06-03. http://www.theage.com.au/news/world/the-deadly-business-of-climbing-everest/2006/06/02/1148956544080.htmlpagefullpage#contentSwap2.  "Chamber of Horrors: The Oxygen Mask". MountainZone.com. 1998-05-21. http://classic.mountainzone.com/everest/98/climb5-21oxygen.html. Retrieved 2007-04-01.  The Mystery of Mallory & Irvine Tom Holzel & Audrey Salkeld 1986. Krakauer Jon (1997). Into Thin Air: A Personal Account of the Mt. Everest Disaster. New York: Villard. ISBN 0-679-45752-6.  p 154 The debate between G. Weston DeWalt and Jon Krakauer on bottled oxygen and Boukreev's actions can be found in the Salon debates "The Oxygen Illusion". The Anatoli Boukreev Memorial Fund. http://www.boukreev.org/The%20Oxygen%20Illusion.htm. Retrieved 2010-06-24.  a b Coming Down page 3 DWIGHT GARNER salon.com 1998 August Boukreev Anatoli; DeWalt Weston (1998). The Climb. St. Martins Paperbacks. p. 182. ISBN 0-312-96533-8.  Mounteverest.net article. See also second article. Go Sell It on the Mountain Mother Jones 1 February 2008 Bristow Michael (2007-07-13). "Everest base camp a 'wild-west town'". BBC News. http://news.bbc.co.uk/2/hi/asia-pacific/6897591.stm. Retrieved 31 March 2010.  Wanless F.R. (1975). Spiders of the family Salticidae from the upper slopes of Everest and Makalu. British Arachnological Society. http://www.britishspiders.org.uk/. Retrieved 2008-03-21.  The Ascent of Everest by John Hunt (Hodder & Stoughton 1953). In chapter 14 Hunt describes seeing a Chough on the South Col; meanwhile Charles Evans saw some unidentified birds fly over the Col a b c d Yin C.-H. and Kuo S.-T. 1978: "Stratigraphy of the Mount Jolmo Langma and its north slope." Scientia Sinica. v. 5 pp. 630644 a b c d e Sakai H. M. SawadaY. Takigami Y. Orihashi T. Danhara H. Iwano Y. Kuwahara Q. Dong H. Cai and J. Li. 2005. "Geology of the summit limestone of Mount Qomolangma (Everest) and cooling history of the Yellow Band under the Qomolangma detachment." Island Arc. v. 14 no. 4 pp. 297310. Gansser A.1964.Geology of the Himalayas John Wiley Interscience London 1964 289 pp. a b c Myrow P. M. N. C. Hughes M. P. Searle C. M. Fanning S.-C. Peng and S. K. Parcha 2009 Stratigraphic correlation of Cambrian Ordovician deposits along the Himalaya: Implications for the age and nature of rocks in the Mount Everest region. Geological Society of America Bulletin. v. 121 no. 3-4 pp. 323332. Searle M. P. 1999. Emplacement of Himalayan leucogranites by magma injection along giant sill complexes: examples from the Cho Oyu Gyachung Kang and Everest leucogranites (Nepal Himalaya). Journal of Asian Earth Sciences. v. 17 no. 5-6 pp. 773783. 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.) Murray W. H. The Story of Everest 19211952 London J. M. Dent & Sons 1953. Newby Eric A Short Walk in the Hindu Kush London Hodder & Stoughton 1958. Tilman H. W. Nepal Himalaya Cambridge University Press 1952. External links Wikimedia Commons has media related to: Mount Everest Wikiquote has a collection of quotations related to: Mount Everest Wikisource has the text of the 1911 Encyclopdia Britannica article Everest Mount. 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 v d eEight-thousanders Everest  K2  Kangchenjunga  Lhotse  Makalu  Cho Oyu  Dhaulagiri  Manaslu  Nanga Parbat  Annapurna  Gasherbrum I  Broad Peak  Gasherbrum II  Shishapangma v d eSeven Summits Asia Everest (8848 m/29029 ft) South America Aconcagua (6962 m/22841 ft) North America Mount McKinley (6198 m/20335 ft) Africa Kilimanjaro (5893 m/19334 ft) Europe Elbrus (5642 m/18510 ft)    or  Mont Blanc (4810 m/15781 ft) Antarctica Vinson Massif (4892 m/16050 ft) Australia (Oceania) Puncak Jaya (4884 m/16024 ft)    or  Mount Wilhelm (4509 m/14793 ft)    or  Mount Kosciuszko (2228 m/7310 ft)  v d eTopography of Mount Everest Three Pinnacles  Hillary Step  Norton Couloir  Hornbein Couloir  Three Steps  South Col Kangshung Face  Kangshung Glacier  Valley of Silence  Khumbu Glacier  Khumbu Icefall  Rongbuk Glacier