A glacier is a persistent body of dense ice that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water.
An avalanche is a rapid flow of snow down a slope, such as a hill or mountain. Avalanches can be triggered spontaneously, by factors such as increased precipitation or snowpack weakening, or by external means such as humans, other animals, and earthquakes. Primarily composed of flowing snow and air, large avalanches have the capability to capture and move ice, rocks, and trees.
An icefall is a portion of certain glaciers characterized by relatively rapid flow and chaotic crevassed surface, caused in part by gravity. The term icefall is formed by analogy with the word waterfall, which is a similar phenomenon of the liquid phase but at a more spectacular speed. When ice movement of a glacier is faster than elsewhere, because the glacier bed steepens or narrows, and the flow cannot be accommodated by plastic deformation, the ice fractures, forming crevasses. Where two fractures meet, seracs can be formed. When the movement of the ice slows down, the crevasses can coalesce, resulting in the surface of the glacier becoming smoother.
Glacial landforms are landforms created by the action of glaciers. Most of today's glacial landforms were created by the movement of large ice sheets during the Quaternary glaciations. Some areas, like Fennoscandia and the southern Andes, have extensive occurrences of glacial landforms; other areas, such as the Sahara, display rare and very old fossil glacial landforms.
The Khumbu Icefall is located at the head of the Khumbu Glacier and the foot of the Western Cwm. It lies at an elevation of 5,486 meters on the Nepali slopes of Mount Everest, not far above Base Camp and southwest of the summit. The icefall is regarded as one of the most dangerous sections of the South Col route to Everest's summit.
A serac is a block or column of glacial ice, often formed by intersecting crevasses on a glacier. Commonly house-sized or larger, they are dangerous to mountaineers, since they may topple with little warning. Even when stabilized by persistent cold weather, they can be an impediment to glacier travel.
The Kolka–Karmadon rock-ice slide occurred on the northern slope of the Mount Kazbek massif in North Ossetia–Alania on 20 September 2002, following a partial collapse of the Kolka Glacier. It started on the north-northeast wall of Mount Jimara, 4,780 m (15,680 ft) above sea level, and seriously affected the valley of Genaldon and Karmadon. The resulting avalanche and mudflow killed more than 120 people, including a film crew of 27 people, among them Russian actor and director Sergei Bodrov Jr. While this type of avalanche is not uncommon, this particular event is considered extraordinary because of several aspects.
Glacier ice accumulation occurs through accumulation of snow and other frozen precipitation, as well as through other means including rime ice, avalanching from hanging glaciers on cliffs and mountainsides above, and re-freezing of glacier meltwater as superimposed ice. Accumulation is one element in the glacier mass balance formula, with ablation counteracting. With successive years in which accumulation exceeds ablation, then a glacier will experience positive mass balance, and its terminus will advance.
Glacier morphology, or the form a glacier takes, is influenced by temperature, precipitation, topography, and other factors. The goal of glacial morphology is to gain a better understanding of glaciated landscapes and the way they are shaped. Types of glaciers can range from massive ice sheets, such as the Greenland ice sheet, to small cirque glaciers found perched on mountain tops. Glaciers can be grouped into two main categories:
Kolka Glacier is a glacier in North Ossetia, Russia, near Mount Kazbek, known for its surging properties. The most recent and the most powerful surge took place on 20 September 2002, resulting in the death of ca. 140 people.
Blue Glacier is a large glacier located to the north of Mount Olympus in the Olympic Mountains of Washington. The glacier covers an area of 1.7 sq mi (4.4 km2) and contains 580,000,000 cu ft (16,000,000 m3) of ice and snow in spite of its low terminus elevation. The glacier length has decreased from about 3.4 mi (5.5 km) in 1800 to 2.7 mi (4.3 km) in the year 2000. Just in the period from 1995 and 2006, Blue Glacier retreated 325 ft (99 m). Blue Glacier is also thinning as it retreats and between 1987 and 2009 the glacier lost 178 ft (54 m) of its depth near its terminus and between 32 and 48 ft in the uppermost sections of the glacier known as the accumulation zone.
Wright Upper Glacier is an ice apron at the upper west end of Wright Valley in the Asgard Range, Antarctica. It is formed by a glacier flowing east from the inland ice plateau. It was named by the Victoria University of Wellington Antarctic Expedition (VUWAE) (1958–59) for C. S. Wright, a member of the British Antarctic Expedition (1910–13), after whom the "Wright Glacier" was named.
Barwick Valley is an ice-free valley north of Apocalypse Peaks, extending from Webb Glacier to Victoria Valley in Victoria Land, Antarctica. A large part of the valley has been designated an Antarctic Specially Protected Area because of its pristine condition.
On 18 April 2014, seracs on the western spur of Mount Everest failed, resulting in an ice avalanche that killed sixteen climbing Sherpas in the Khumbu Icefall. This was the same icefall where the 1970 Mount Everest disaster had taken place. Thirteen bodies were recovered within two days, while the remaining three were never recovered due to the great danger in attempting such an expedition. Many Sherpas were angered by what they saw as the Nepalese government's meager offer of compensation to victims' families, and threatened a protest or strike. On 22 April, the Sherpas announced they would not work on Everest for the remainder of 2014 as a mark of respect for the victims.
The Rob Roy Glacier is a small hanging glacier in the Southern Alps of New Zealand's South Island. It is located within the Mount Aspiring National Park, 9 kilometres (6 mi) south of Mount Aspiring / Tititea.
The 1970 Huascarán Debris Avalanche occurred on May 30 1970, when a debris avalanche and mudflow triggered by the Ancash earthquake destroyed the Peruvian town of Yungay and ten nearby villages, leaving up to 30,000 people dead. It is the deadliest avalanche or glacier-related disaster in history, surpassing the death toll from the previous deadliest avalanche disaster, the avalanches of White Friday on the Italian front of World War I and the third or fourth most deadly landslide-related disaster of the 20th century, after the Haiyuan landslides (China), the Armero tragedy (Colombia) and by some estimates the Khait landslide (Tajikistan).
The 1955 British Kangchenjunga expedition succeeded in climbing the 28,168-foot (8,586 m) Kangchenjunga, the third highest mountain in the world, for the first time. The expedition complied with a request from the Sikkim authorities that the summit should not be trodden on so the climbers deliberately stopped about five feet below the summit. George Band and Joe Brown reached the top on 25 May 1955, and they were followed the next day by Norman Hardie and Tony Streather. The expedition was led by Charles Evans who had been deputy leader on the 1953 British Mount Everest expedition.
The 2021 Uttarakhand flood, also known as the Chamoli disaster, began on 7 February 2021 in the environs of the Nanda Devi National Park, a UNESCO World Heritage Site in the outer Garhwal Himalayas in Uttarakhand state, India. It was caused by a large rock and ice avalanche consisting of material dislodged from Ronti peak. It caused flooding in the Chamoli district, most notably in the Rishiganga river, the Dhauliganga river, and in turn the Alaknanda—the major headstream of the Ganges. The disaster left over 200 killed or missing. Most were workers at the Tapovan dam site.
Rishiganga is a river in the Chamoli district, Uttarakhand, India. It springs from the Uttari Nanda Devi Glacier on the Nanda Devi mountain. It is also fed from the Dakshini Nanda Devi Glacier. Continuing through the Nanda Devi National Park, it flows into the Dhauliganga River near the village Rini.
Karmadon (Genaldon) gorge is a gorge in North Ossetia. The Genaldon river of the Greater Caucasus mountain system flows in the gorge. In the upper reaches of the gorge there are two glaciers: Kolka and Mayli. It is located at altitudes from 750 m to 1200 m above sea level.
