A glacier is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. Glaciers slowly deform and flow under stresses induced by their weight, creating crevasses, seracs, and other distinguishing features. They also abrade rock and debris from their substrate to create landforms such as cirques, moraines, or fjords. Glaciers form only on land and are distinct from the much thinner sea ice and lake ice that forms on the surface of bodies of water.
Mount Shasta is a potentially active volcano at the southern end of the Cascade Range in Siskiyou County, California. At an elevation of 14,179 feet, it is the second-highest peak in the Cascades and the fifth-highest in the state. Mount Shasta has an estimated volume of 85 cubic miles, which makes it the most voluminous stratovolcano in the Cascade Volcanic Arc. The mountain and surrounding area are part of the Shasta–Trinity National Forest.
Glaciology is the scientific study of glaciers, or more generally ice and natural phenomena that involve ice.
An ice shelf is a large floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface. Ice shelves are only found in Antarctica, Greenland, Northern Canada, and the Russian Arctic. The boundary between the floating ice shelf and the anchor ice that feeds it is the grounding line. The thickness of ice shelves can range from about 100 m (330 ft) to 1,000 m (3,300 ft).
Hubbard Glacier is a glacier located in Wrangell–St. Elias National Park and Preserve in eastern Alaska and Kluane National Park and Reserve in Yukon, Canada, and named after Gardiner Hubbard.
Mendenhall Glacier is a glacier about 13.6 miles (21.9 km) long located in Mendenhall Valley, about 12 miles (19 km) from downtown Juneau in the southeast area of the U.S. state of Alaska. The glacier and surrounding landscape is protected as part of the 5,815 acres (2,353 ha) Mendenhall Glacier Recreation Area, a federally designated unit of the Tongass National Forest.
Haupapa / Tasman Glacier is the largest glacier in New Zealand, and one of several large glaciers which flow south and east towards the Mackenzie Basin from the Southern Alps in New Zealand's South Island.
The Greenland ice sheet is a vast body of ice covering 1,710,000 square kilometres (660,000 sq mi), roughly near 80% of the surface of Greenland.
Crucial to the survival of a glacier is its mass balance or surface mass balance (SMB), the difference between accumulation and ablation. Climate change may cause variations in both temperature and snowfall, causing changes in the surface mass balance. Changes in mass balance control a glacier's long-term behavior and are the most sensitive climate indicators on a glacier. From 1980 to 2012 the mean cumulative mass loss of glaciers reporting mass balance to the World Glacier Monitoring Service is −16 m. This includes 23 consecutive years of negative mass balances.
The retreat of glaciers since 1850 affects the availability of fresh water for irrigation and domestic use, mountain recreation, animals and plants that depend on glacier-melt, and, in the longer term, the level of the oceans. Studied by glaciologists, the temporal coincidence of glacier retreat with the measured increase of atmospheric greenhouse gases is often cited as an evidentiary underpinning of global warming. Mid-latitude mountain ranges such as the Himalayas, Rockies, Alps, Cascades, and the southern Andes, as well as isolated tropical summits such as Mount Kilimanjaro in Africa, are showing some of the largest proportionate glacial losses.
The Mud Creek Glacier is the southernmost glacier on Mount Shasta in the U.S. state of California. It lies to the east of Sargents Ridge on Shastarama point near 10,915 feet (3,327 m) above sea level. The glacier is smaller than the northern ones on Mount Shasta such as Whitney, Hotlum, Bolam, and Wintun Glaciers. There are approximately 80 glaciers in California and unlike the glaciers in Alaska, Colorado and Montana. California’s existing current glaciers are not remnants of the Pleistocene, but instead relatively young approximately 1,000 years in age. The Mud Creek Glacier is one of at least 7 recognized glaciers on Mt. Shasta by the United States Geological Survey (USGS) the rest being: Whitney, Hotlum, Bolam, Wintun, Konwakiton, and Watkins.
The Hotlum Glacier is a glacier situated on the northeast flank of Mount Shasta, in the US state of California. It is the largest and most voluminous glacier in California, although not as thick or long as the nearby Whitney Glacier. The Hotlum Glacier flows from a large cirque on the northeast side of Mount Shasta's main summit below the Hotlum Headwall at roughly 13,600 ft (4,100 m). It flows northeastward down the steep slope, forming three lobes which terminate near 10,400 ft (3,200 m).
The Bolam Glacier is a glacier situated on the northern flank of Mount Shasta, in the U.S. state of California. It is the second longest glacier in California behind the nearby Whitney Glacier, and the fourth largest and most voluminous after the neighboring Hotlum Glacier, Whitney Glacier, and Wintun Glacier. The Bolam Glacier flows from a cirque on the north side of Mount Shasta's main summit, with the moving ice starting below a large bergschrund which spans the glacier at 12,600 ft (3,800 m). Above that, permanent snow and ice extends towards the summit to about 13,500 ft (4,100 m). The glacier flows north down a steep slope and terminates near 9,800 ft (3,000 m). It has a contributing drainage area of 1.03 km2.
The Wintun Glacier is a glacier situated on the eastern flank of Mount Shasta, in the U.S. state of California. It is both the third largest and third most voluminous glacier in California after the neighboring Hotlum Glacier and the Whitney Glacier. The Wintun Glacier starts on the east side of Mount Shasta's main summit, and it has the highest permanent snow and ice on the mountain, reaching above 14,100 ft (4,300 m) to within a few dozen feet of the true summit. The glacier flows east down a steep slope and terminates in two lobes, the longer of which extends down near 9,800 ft (3,000 m).
The Konwakiton Glacier is a glacier situated on the southern flank of Mount Shasta, in the U.S. state of California. It occupies the head of a large cirque on the south side of Shasta's Misery Hill cone, just northeast of the prominent outcrop of Thumb Rock at about 11,500 ft (3,500 m). It is the fifth largest glacier on Mount Shasta, although less than one-third the size of any of the four larger ones. The Konwakiton is the most frequently visited of Shasta's glaciers, since the standard climbing route up Avalanche Gulch skirts along its western edge above Thumb Rock saddle, with the boot track often only a few feet from the bergschrund at the glacier's head.
The Watkins Glacier is a glacier situated on the southeastern flank of Mount Shasta, in the U.S. state of California. It occupies a small cirque in the Clear Creek drainage. It is the smallest officially-named glacier on Mount Shasta, and it was not accorded that status until 1976, following a decades-long campaign by local resident R. Harry Watkins, Jr., to bring recognition to the previously-ignored glacier.
The tidewater glacier cycle is the typically centuries-long behavior of tidewater glaciers that consists of recurring periods of advance alternating with rapid retreat and punctuated by periods of stability. During portions of its cycle, a tidewater glacier is relatively insensitive to climate change.
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.
Hooker Lake is a proglacial lake that started to form in the late 1970s by the recent retreat of the Hooker Glacier. It is in the Hooker Valley, in the Aoraki / Mount Cook National Park in New Zealand's South Island, just south of Aoraki / Mount Cook.
A glacier head is the top of a glacier. Although glaciers seem motionless to the observer they are in constant motion and the terminus is always either advancing or retreating.
