- 업종: Government
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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.
The addition of ice and snow into a glacier system. This occurs through a variety of processes including precipitation, firnification, and wind transportation of snow into a glacier basin from an adjacent area.
Industry:Water bodies
A mass of snow that has accumulated in the top of an open crevasse, masking the existence of the crevasse. Frequently, a large void exists below the snowbridge.
Industry:Water bodies
A cave formed in or under a glacier, typically by running water. Steam or high heat flow can also form glacier caves. Also called Ice Cave.
Industry:Water bodies
The balance between changes within the Earth's crust and mantle, where material is displaced in response to an increase (isostatic depression) or decrease (isostatic rebound) in mass at any point on the Earth's surface above. Such changes are frequently caused by advances or retreats of glaciers.
Industry:Water bodies
A sediment ridge, located on a glacier's exposed ice surface, away from its valley walls, extending down glacier to the terminus. It forms by the joining of two lateral moraines when two glaciers merge.
Industry:Water bodies
A broad, low-slope angle alluvial plain composed of glacially eroded, sorted sediment (termed outwash), that has been transported by meltwater. The alluvial plain begins at the foot of a glacier and may extend for miles. Typically, the sediment becomes finer grained with increasing distance from the glacier terminus.
Industry:Water bodies
A cross-valley, ridge-like accumulation of glacial sediment that forms at the farthest point reached by the terminus of an advancing glacier.
Industry:Water bodies
An isolated melting mass of glacier ice, that has become detached from its source and the remainder of the glacier. Some remnants cover many square miles.
Industry:Water bodies
The most recent interval of temperate glacier expansion and advance on Earth. It began ~650 years ago and continued into the 20th century in many locations. Temperate glaciers in North America, South America, Africa, Europe, and Asia were affected.
Industry:Water bodies
A meandering, water-deposited, generally steep-sided sediment ridge that forms within a subglacial or englacial stream channel. Its floor can be bedrock, sediment, or ice. Subsequent melting of the glacier exposes the deposit. Generally composed of stratified sand and gravel, eskers can range from feet to miles in length and may exceed 100 feet in height.
Industry:Water bodies
