Introduction to the Clues
"Some day you will hear a different story."
On 8th June 1924, George Mallory and Andrew Irvine left their high camp at approximately 26,700ft on the North Ridge of Mount Everest in a bid to reach the summit. The exact route taken by the pair is unknown, but Mallory is thought to have favoured the Northeast Ridge option over Colonel Norton's traverse into the Couloir.
Mallory's Notes
In two final notes, written on 7th June to "support" climber Noel Odell and to expedition photographer Captain Noel respectively, Mallory gave these indications of his plans:
"To here on 90 atmospheres for the two days we'll probably go on two cylinders but it's a bloody load for climbing. Perfect weather for the job!"
"We'll probably start early tomorrow (8th) in order to have clear weather. It won't be too early to start looking for us either crossing the rock band under the pyramid or going up skyline at 8.0pm."
The time given by Mallory was surely a mistake for "8.0am", and Captain Noel understood Mallory's possible movements in terms of locations on the final pyramid rather than in terms of the choice between the ridge and Norton's route.
Odell's Sighting
On the day of the attempt, Odell was moving up to the top camp in support of the anticipated return of Mallory and Irvine. In a brief moment of atmospheric visibility at 12.50pm, he caught sight of the pair approaching and then climbing a rock step in the Northeast Ridge. Although he originally believed this rock feature to be the second step, he later decided it was the first step and maintained this opinion for the rest of his life.
The Ice Axe
In the course of the 1933 expedition, the first climbing party of Lawrence Wager and Percy Wyn-Harris recovered an ice axe bearing the personal mark of Irvine from a little below the crest of the Northeast Ridge. It appeared to have been placed on a gently sloping 'boiler plate' slab approximately 250 feet below the base of the first step, and the 1933 expedition believed this spot marked the site of a slip.
The Chinese
In 1960, a Chinese expedition made the first ascent of Everest from the north side, opting for the ridge route over the Norton traverse which had pre-occupied most of the British pre-war climbers. Although they were delayed for three hours at the headwall of the second step, porter Qu Yinhua eventually climbed the step with the aid of a shoulder stand from one of his companions and a piton nailed into a crack in the rock. Hence, the Chinese proved that the second step could be climbed, but only in extremis since Qu was required to remove his boots to get purchase on the rock and subsequently lost his toes and heel to frostbite. Later attempts on the Northeast Ridge have made use of a metal ladder left by a subsequent Chinese expedition at this critical point.
The "English Dead"
The next piece of evidence dates from 1975, when Chinese climber Wang Hongbao vaguely described to his companion how he found an 'English Dead' while taking a walk from his camp at approximately 26,800ft on the North Face. The body must have belonged to either Mallory or Irvine, since they were the only Westerners to have died that high on the mountain prior to the Chinese expeditions. Wang apparently described a body with a hole in the cheek and disintegrated clothing, but he died in an accident soon after this conversation and was unable to provide further details of his find.
Finding Mallory
In 1999, an expedition investigating the mystery of Mallory and Irvine made a number of important discoveries. Firstly, the body of George Mallory was found at the bottom of a snowfield on the North Face, roughly below the ice axe site and within walking distance of Wang's camp. A length of rope around Mallory's waist led to a broken end and seemed to indicate that the two climbers were together when an accident took place. Unlike other fallen climbers discovered in the snowfield, Mallory's posture was one of apparent self-arrest. No camera was found in the vicinity of the body, and it was noted that Mallory was not wearing his snow goggles - a pair were found folded in his pocket. Although notes written on an envelop in Mallory's pocket provided an inventory of oxygen cylinders available to the pair, it is unclear as to when this inventory was made during their ascent from camp three.
The Oxygen Bottle
The 1999 expedition also retrieved an oxygen bottle used by either Mallory or Irvine during their summit attempt. This bottle - "number nine" - had originally been spotted but not identified by Eric Simonson in 1991. It was found slightly below the crest of the Northeast Ridge and roughly between the ice axe site and the base of the first step.
The Second Step
Also in 1999, the accomplished climber Conrad Anker attempted to free-climb the headwall of the second step. Despite making swift progress on an off-width crack, Anker was forced briefly to step onto the Chinese ladder. After some prevarication, which included saying "I think Mallory could have done that" immediately after the climb, he rated the pitch at a level of technical difficulty not thought to have been overcome by Mallory during any of his climbs.
Postscript
In 2001, the research team returned to Everest and continued looking for clues. The most significant discovery was that of a mitten, thought to have belonged to either Mallory or Irvine, at the top of a gully defining the modern route through the yellow band to the Northeast Ridge.
Also in 2001, Jochen Hemmleb and Eric Simonson interviewed the 1960 Chinese expedition vice-leader Xu Jing. He claimed to have found a body in a sleeping bag in a gully running down from the ridge at approximately 27,230ft. However, this sighting is unconfirmed at the time of writing.
Notes
See Pete Poston's site for photographs of the North Face with the locations of Mallory and Irvine clues highlighted.
Mallory's full note read: "we're awfully sorry to have left things in such a mess our Unna Cooker rolled down the slope at the last moment. Be sure of getting back to IV to-morrow in time to evacuate before dark, as I hope to. In the tent I must have left a compass for the Lord's sake rescue it: we are here without. To here on 90 atmospheres for the two days we'll probably go on two cylinders but it's a bloody load for climbing. Perfect weather for the job!"
Anker initially rated the Second Step pitch 5.8, but later revised his estimate to 5.10, beyond the standards of 1924, after comparison with climbs he had done in the United States.