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The scientific agency of the United States Department of the Interior, USGS's mission is to provide information to describe and understand the earth, its natural resources, and the natural hazards that threaten it.
A glacier that flows for all or most of its length within the walls of a mountain valley. Also called an alpine glacier or a mountain glacier.
Industry:Water bodies
The current part of geologic time. The Holocene epoch began ~12,000 years ago, at the end of the Pleistocene epoch.
Industry:Water bodies
A sediment ridge, located on a glacier's surface adjacent to the valley walls, extending down glacier to the terminus. It forms by the accumulation of rock material falling onto the glacier from the valley wall, rather than by water deposition.
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A valley with a parabolic or "U" shaped cross-section, steep walls and generally a broad and flat floor. Formed by glacier erosion, a U-shaped valley results when a glacier widens and over-steepens a V-shaped stream valley.
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A narrow, tubular chute or crevasse through which water enters a glacier from the surface. Occasionally, the lower end of a moulin may be exposed in the face of a glacier or at the edge of a stagnant block of ice.
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A series of small, closely spaced, crescentic grooves or scars formed in bedrock by rocks frozen in basal ice as they move along and chip the glacier's bed. The horns of the crescent generally point down glacier.
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A glacier formed below the terminus of a hanging glacier by the accumulation, and reconstitution by pressure melting (regelation), of ice blocks that have fallen and/or avalanched from the terminus of the hanging glacier.
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An irregular-shaped layer or pile of glacier sediment formed by the melting of a block of stagnant ice. Ultimately, ablationa moraine is deposited on the former bed of the glacier.
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An increase in the length of a glacier compared to a previous point in time. As ice in a glacier is always moving forward, a glacier's terminus advances when less ice is lost due to melting and/or calving than the amount of yearly advance.
Industry:Water bodies
A glacially eroded or modified U-shaped valley that extends below sea level and connects to the ocean. Filled with seawater, depths may reach more than 1,000 feet below sea level. The largest Alaskan fiords are more than 100 miles long and more than 5 miles wide. Also spelled Fiord.
Industry:Water bodies
