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A glacier cave is a cave formed within the ice of a glacier. Glacier caves are often called ice caves, but the latter term is properly used to describe bedrock caves that contain year-round ice. [1]
Most glacier caves are started by water running through or under the glacier. This water often originates on the glacier's surface through melting, entering the ice at a moulin and exiting at the glacier's snout at base level. Heat transfer from the water can cause sufficient melting to create an air-filled cavity, sometimes aided by solifluction. Air movement can then assist enlargement through melting in summer and sublimation in winter.
Some glacier caves are formed by geothermal heat from volcanic vents or hotsprings beneath the ice. An extreme example is the Kverkfjöll glacier cave in the Vatnajökull glacier in Iceland, measured in the 1980s at 2.8 kilometres (1.7 mi) long with a vertical range of 525 metres (1,722 ft).
Some glacier caves are relatively unstable due to melting and glacial motion, and are subject to localized or complete collapse, as well as elimination by glacial retreat. An example of the dynamic nature of glacier caves is the former Paradise Ice Caves, located on Mount Rainier in the United States. Known since the early 1900s, the caves were thought to have disappeared altogether in the mid-1940s, yet in 1978 cavers measured 13.25 kilometres (8.23 mi) of passageways in glacier caves there, and it was then considered the longest glacier cave system in the world. The Paradise Ice Caves collapsed and vanished in the 1990s, and the lower lobe of the glacier which once contained the caves has also vanished entirely between 2004 and 2006.
Glacier caves may be used by glaciologists to gain access to the interior of glaciers. The study of glacier caves themselves is sometimes called "glaciospeleology".
Mount Baker, also known as Koma Kulshan or simply Kulshan, is a 10,781 ft (3,286 m) active glacier-covered andesitic stratovolcano in the Cascade Volcanic Arc and the North Cascades of Washington in the United States. Mount Baker has the second-most thermally active crater in the Cascade Range after Mount St. Helens. About 30 miles (48 km) due east of the city of Bellingham, Whatcom County, Mount Baker is the youngest volcano in the Mount Baker volcanic field. While volcanism has persisted here for some 1.5 million years, the current volcanic cone is likely no more than 140,000 years old, and possibly no older than 80–90,000 years. Older volcanic edifices have mostly eroded away due to glaciation.
Eyjafjallajökull, sometimes referred to by the numeronym E15, is one of the smaller ice caps of Iceland, north of Skógar and west of Mýrdalsjökull. The ice cap covers the caldera of a volcano with a summit elevation of 1,651 metres (5,417 ft). The volcano has erupted relatively frequently since the Last Glacial Period, most recently in 2010, when, although relatively small for a volcanic eruption, it caused enormous disruption to air travel across northern and western Europe for a week.
A jökulhlaup is a type of glacial outburst flood. It is an Icelandic term that has been adopted in glaciological terminology in many languages. It originally referred to the well-known subglacial outburst floods from Vatnajökull, Iceland, which are triggered by geothermal heating and occasionally by a volcanic subglacial eruption, but it is now used to describe any large and abrupt release of water from a subglacial or proglacial lake/reservoir.
An outwash plain, also called a sandur, sandr or sandar, is a plain formed of glaciofluvial deposits due to meltwater outwash at the terminus of a glacier. As it flows, the glacier grinds the underlying rock surface and carries the debris along. The meltwater at the snout of the glacier deposits its load of sediment over the outwash plain, with larger boulders being deposited near the terminal moraine, and smaller particles travelling further before being deposited. Sandurs are common in Iceland where geothermal activity accelerates the melting of ice flows and the deposition of sediment by meltwater.
The Garibaldi Volcanic Belt is a northwest–southeast trending volcanic chain in the Pacific Ranges of the Coast Mountains that extends from Watts Point in the south to the Ha-Iltzuk Icefield in the north. This chain of volcanoes is located in southwestern British Columbia, Canada. It forms the northernmost segment of the Cascade Volcanic Arc, which includes Mount St. Helens and Mount Baker. Most volcanoes of the Garibaldi chain are dormant stratovolcanoes and subglacial volcanoes that have been eroded by glacial ice. Less common volcanic landforms include cinder cones, volcanic plugs, lava domes and calderas. These diverse formations were created by different styles of volcanic activity, including Peléan and Plinian eruptions.
Mount Melbourne is a 2,733-metre-high (8,967 ft) ice-covered stratovolcano in Victoria Land, Antarctica, between Wood Bay and Terra Nova Bay. It is an elongated mountain with a summit caldera filled with ice with numerous parasitic vents; a volcanic field surrounds the edifice. Mount Melbourne has a volume of about 180 cubic kilometres (43 cu mi) and consists of tephra deposits and lava flows; tephra deposits are also found encased within ice and have been used to date the last eruption of Mount Melbourne to 1892 ± 30 years. The volcano is fumarolically active.
A subglacial volcano, also known as a glaciovolcano, is a volcanic form produced by subglacial eruptions or eruptions beneath the surface of a glacier or ice sheet which is then melted into a lake by the rising lava. Today they are most common in Iceland and Antarctica; older formations of this type are found also in British Columbia and Yukon Territory, Canada.
Mount Wrangell, in Ahtna K’ełt’aeni or K’ełedi when erupting, is a massive shield volcano located in Wrangell-St. Elias National Park and Preserve in southeastern Alaska, United States. The shield rises over 12,000 feet (3,700 m) above the Copper River to its southwest. Its volume is over 220 cubic miles (920 km3), making it more than twice as massive as Mount Shasta in California, the largest stratovolcano by volume in the Cascades. It is part of the Wrangell Volcanic Field, which extends for more than 250 kilometers (160 mi) across Southcentral Alaska into the Yukon Territory in Canada, and has an eruptive history spanning the time from Pleistocene to Holocene.
A glacial lake outburst flood (GLOF) is a type of outburst flood caused by the failure of a dam containing a glacial lake. An event similar to a GLOF, where a body of water contained by a glacier melts or overflows the glacier, is called a jökulhlaup. The dam can consist of glacier ice or a terminal moraine. Failure can happen due to erosion, a buildup of water pressure, an avalanche of rock or heavy snow, an earthquake or cryoseism, volcanic eruptions under the ice, or massive displacement of water in a glacial lake when a large portion of an adjacent glacier collapses into it.
A tuya is a flat-topped, steep-sided volcano formed when lava erupts through a thick glacier or ice sheet. They are rare worldwide, being confined to regions which were covered by glaciers and had active volcanism during the same period.
Meltwater is water released by the melting of snow or ice, including glacial ice, tabular icebergs and ice shelves over oceans. Meltwater is often found during early spring when snow packs and frozen rivers melt with rising temperatures, and in the ablation zone of glaciers where the rate of snow cover is reducing. Meltwater can be produced during volcanic eruptions, in a similar way in which the more dangerous lahars form.
Several types of volcanic eruptions—during which lava, tephra, and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series.
Phreatomagmatic eruptions are volcanic eruptions resulting from interaction between magma and water. They differ from exclusively magmatic eruptions and phreatic eruptions. Unlike phreatic eruptions, the products of phreatomagmatic eruptions contain juvenile (magmatic) clasts. It is common for a large explosive eruption to have magmatic and phreatomagmatic components.
Paradise Glacier is a glacier on the southeast flank of Mount Rainier in Washington. It covers 0.4 square miles (1.0 km2) and contains 0.8 billion ft3 with Stevens Glacier included. The glacier is bounded to the west by the Muir Snowfield, Anvil Rock and McClure Rock. There is a single extant main lobe of the glacier, ranging from 9,000 feet (2,700 m) to 7,200 feet (2,200 m), that is connected to the larger Cowlitz Glacier. To the south, there was a smaller portion which was near the Cowlitz Rocks and the tiny Williwakas Glacier, ranging from 6,900 feet (2,100 m) to 6,400 ft (2,000 m) in elevation and containing the Paradise Ice Caves until the 1990s. This smaller lobe melted between 2004 and 2006. Meltwater from the glacier drains into the Cowlitz River.
Ice sheet dynamics describe the motion within large bodies of ice, such those currently on Greenland and Antarctica. Ice motion is dominated by the movement of glaciers, whose gravity-driven activity is controlled by two main variable factors: the temperature and the strength of their bases. A number of processes alter these two factors, resulting in cyclic surges of activity interspersed with longer periods of inactivity, on both hourly and centennial time scales. Ice-sheet dynamics are of interest in modelling future sea level rise.
The Mount Edziza volcanic complex is a large and potentially active north-south trending complex volcano in Stikine Country, northwestern British Columbia, Canada, located 38 kilometres (24 mi) southeast of the small community of Telegraph Creek. It occupies the southeastern portion of the Tahltan Highland, an upland area of plateau and lower mountain ranges, lying east of the Boundary Ranges and south of the Inklin River, which is the east fork of the Taku River. As a volcanic complex, it consists of many types of volcanoes, including shield volcanoes, calderas, lava domes, stratovolcanoes, and cinder cones.
Mount Rainier, also known as Tahoma, is a large active stratovolcano in the Cascade Range of the Pacific Northwest in the United States. The mountain is located in Mount Rainier National Park about 59 miles (95 km) south-southeast of Seattle. With a summit elevation of 14,417 ft (4,394 m), it is the highest mountain in the U.S. state of Washington and the Cascade Range, the most topographically prominent mountain in the contiguous United States, and the tallest in the Cascade Volcanic Arc.
The Sandy Glacier Caves are a system of glacier caves within the ice of Sandy Glacier on Mount Hood, Oregon. They are thought to be the largest glacier caves in the lower 48 states of the United States. Surveys done in 2011 and 2012 have measured the system at over 1 mile in length or about 7,000 feet. The caves formed from internal glacial melting at what are the headwaters of the Muddy Fork river. As melting continues, the caves grow larger with their entrances melting their way up the glacier's slope. Eventually it is predicted the caves will be completely gone within 7 to 10 years once the interior melting has reached the surface of the glacier.
The Skaftá is a river in South Iceland. It is primarily glacial in origin and has had its course modified by volcanic activity; as a result of both, it often floods because of glacial melting.
Ice cauldrons are ice formations within glaciers that cover some subglacial volcanoes. They can have circular to oblong forms. Their surface areas reach from some meters to up to 1 or more kilometers.
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