Nabesna Glacier is a

glacier 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. It acquires distinguishing features, such a ...

in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sove ...

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...

. Fed by deep

snowfall Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout ...

in the Wrangell Mountains, the 53 mile (85 km) long Nabesna is the longest

valley glacier A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams ...

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

and the world's longest interior valley glacier. The glacier flows from an extensive

icefield An ice field (also spelled icefield) is a mass of interconnected valley glaciers (also called mountain glaciers or alpine glaciers) on a mountain mass with protruding rock ridges or summits. They are often found in the colder climates and highe ...

which covers the northern flanks of

Mount Wrangell 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 above the Copper River to it ...

, a large

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more vi ...

. It heads initially east past other volcanic peaks including

Mount Blackburn Mount Blackburn is the highest peak in the Wrangell Mountains of Alaska in the United States. It is the fifth-highest peak in the United States and the twelfth-highest peak in North America. The mountain is an old, eroded shield volcano, the se ...

and

Atna Peaks Atna Peaks is an eroded stratovolcano or shield volcano in the Wrangell Mountains of eastern Alaska. It is located in Wrangell–Saint Elias National Park about east of Mount Blackburn, the second-highest volcano in the United States, and just ...

and then turns north to its

terminus Terminus may refer to: * Bus terminus, a bus station serving as an end destination * Terminal train station or terminus, a railway station serving as an end destination Geography *Terminus, the unofficial original name of Atlanta, Georgia, United ...

near 3,000 ft (900 m) elevation, about south of the old mining settlement of Nabesna at the end of the

Nabesna Road The Nabesna Road is a minor highway in the U.S. state of Alaska that extends from the Slana River to Nabesna, providing access to some interior components of Wrangell-St. Elias National Park. The entire length of the road is gravel and has few ...

. The vast expanse and length of the Nabesna is fed by approximately 40 tributary glaciers. Melting ice at its terminus forms the

Nabesna River The Nabesna River (''Naambia Niign'' in Upper Tanana) is a tributary of the Tanana River in the U.S. state of Alaska. Beginning at Nabesna Glacier in the Alaska Range, it flows north-northeast from Wrangell–St. Elias National Park and Prese ...

, which flows northward through

Tetlin National Wildlife Refuge Tetlin National Wildlife Refuge is a dynamic landscape made up of forests, wetlands, tundra, lakes, mountains and glacial rivers bounded by the snowy peaks of the Alaska Range. This upper Tanana River valley has been called the "Tetlin Passage," be ...

and into the Tanana River.

Geography

The glacier was named for the Nabesna River in 1902 by F. C. Schrader of the U.S. Geological Survey. It provides the normal route of access into the heart of the eastern Wrangell Mountains, for

ski mountaineer Ski mountaineering (abbreviated to skimo) is a skiing discipline that involves climbing mountains either on skis or carrying them, depending on the steepness of the ascent, and then descending on skis. There are two major categories of equipmen ...

s, climbers, and scientists. Ski-equipped

bush plane A bush airplane is a general aviation aircraft used to provide both scheduled and unscheduled passenger and flight services to remote, undeveloped areas, such as the Canadian north or bush, Alaskan tundra, the African bush, or savanna, Amazon r ...

s can typically land between 6,000 and 7,000 ft (1,800-2,100 m) on the central portion of the glacier when the ice and

crevasses A crevasse is a deep crack, that forms in a glacier or ice sheet that can be a few inches across to over 40 feet. Crevasses form as a result of the movement and resulting stress associated with the shear stress generated when two semi-rigid pi ...

are covered by winter snow. The glacier has been undergoing a slow, near-continuous retreat since at least the early 1900s. There is evidence to indicate that this retreat may have been going on even longer than that, as glacial deposits much farther down the valley indicate that it may have once been over 200 miles long.

Geography

References

See also