A glacier is a large, perennial accumulation of crystalline ice, snow, rock, sediment, and often liquid water that originates on land and moves down slope under the influence of its own weight and gravity.
Definitions of often used glaciology and glacial geology terms can be found at the USGS Glacier Photoglossary Web site.
While there is no global standard for what size a body of ice must be to be considered a glacier, USGS scientists in Glacier National Park use the commonly accepted guideline of 0.1 square kilometers (about 25 acres) as the minimum size of a glacier.
No, it does not. The term actually refers to changes in the position of the glacier’s terminus over a period of time. Like water, ice flows down its surface gradient and never goes back up valley.
In addition to qualitative methods like Repeat Photography, USGS scientists in Glacier National Park collect quantitative measurements of glacier area and mass balance to track how some o
What are "Benchmark Glaciers" and what are the scientific objectives of the USGS "Benchmark Glaciers" Program?
The term “Benchmark Glaciers” refers to three North American glaciers that have been selected to be the subjects of a long-term glacier monitoring program which investigates climate, glacier geometry, glacier mass balance, glacier motion, and stream ru
Repeat photographs provide a good way to see how Alaska's glaciers are changing.
Glaciers act as reservoirs of water that persist through summer. Continual melt from glaciers contributes water to the ecosystem throughout dry months, creating perennial stream habitat and a water source for plants and animals.
“Eustacy” refers to a change in global sea level. For much of its multi-billion year history, Earth has experienced hundreds of periods of eustatic rise and eustatic fall of sea level.
How does present glacier extent and sea level compare to the extent of glaciers and global sea level during the Last Glacial Maximum (LGM)?
The Last Glacial Maximum (LGM) occurred about 20,000 years ago, during the last phase of the Pleistocene. At that time, glaciers covered: ~ 8 % of Earth’s surface ~ 25 % of Earth’s land area, and
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