- 行业: Government
- Number of terms: 1577
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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.
An area of fresh, vegetation-free bedrock around the margin of a retreating glacier that documents the recent loss of ice.
Industry:Water bodies
A short-lived, frequently large-scale, increase in the rate of movement of the ice within a glacier. Ice velocities may increase 10 to 100 times above normal flow rates. In some surges, the terminus of a glacier rapidly advances. Although not all glaciers surge, those that do often surge with some sort of a periodicity.
Industry:Water bodies
A ridge or pile of unstratified glacial sediment that is formed in front of the ice margin by the terminus of an advancing glacier, bulldozing sediment in its path.
Industry:Water bodies
A single large crevasse or series of sub-parallel crevasses that develop at the head of a glacier. The location where ice pulls away from the bedrock wall of the cirque against which it accumulated. In winter, the crevasse fills with snow. In spring or summer, it reopens. This is originally a German term.
Industry:Water bodies
A measure of the change in mass of a glacier at a certain point for a specific period of time. The balance between accumulation and ablation.
Industry:Water bodies
The epoch of geologic time, informally called the 'The Great Ice Age' or the 'Glacial Epoch', that began ~1.8 million years ago and ended ~8,000 years ago (see the CVO's Geologic Time Scale). During this interval continental glaciers repeatedly formed and covered significant parts of the Earth's surface. Together, the Holocene and Pleistocene epochs comprise the Quaternary Period.
Industry:Water bodies
A former tributary glacier valley that is incised into the upper part of a U-shaped glacier valley, higher than the floor of the main valley. Hanging valley streams often enter the main valley as waterfalls.
Industry:Water bodies
A glacier outburst flood resulting from the failure of a glacier-ice-dam, glacier-sediment-dam, or from the melting of glacier ice by a volcanic eruption (Icelandic).
Industry:Water bodies
A rock that is balanced on a pedestal of ice, and elevated above the surface of a glacier. The rock protects the pedestal of ice from melting by insulating it from the sun.
Industry:Water bodies
An accumulation of standing liquid water on (supraglacial), in (englacial), or under (subglacial) a glacier.
Industry:Water bodies
