USGS home page

Glossary of Glacier Terminology


North-looking oblique aerial photograph showing vegetation growing on the stagnant and melting terminus of Bering Glacier, Alaska. The foreground field of view is ~300 m wide. Bering Glacier flows through Wrangell-Saint Elias National Park.

Ablation

The loss of ice and snow from a glacier system. This occurs through a variety of processes including melting and runoff, sublimation, evaporation, calving, and wind transportation of snow out of a glacier basin.


Northeast-looking oblique aerial photograph showing the thinning and retreating terminus of McBride Glacier, Glacier Bay National Park, Alaska. The width of the glacier is ~ .5 miles.

North-looking photograph showing multiple accumulation layers exposed in a very large crevasse, upper Taku Glacier, Tongass National Forest, Alaska. Note the person and oversnow vehicle for scale.

Accumulation

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.


Photograph showing scientist collecting snow cores for snow density analysis, from the wall of a snow pit, upper Taku Glacier, Juneau Icefield, Tongass National Forest, Alaska.

Northwest-looking oblique aerial photograph showing part of the higher elevation accumulation area of the Fairweather Range, Glacier Bay National Park, Alaska.

Accumulation Area

The part of a glacier that is perennially covered with snow. Also called Névé.


Northeast-looking oblique aerial photograph showing the snow-covered summit accumulation area of Mount Fairweather, Fairweather Range, Glacier Bay National Park, Alaska.

Northeast-looking oblique aerial photograph showing the east margin of the Taku Glacier advancing into the adjacent forest, Juneau Icefield, Tongass National Forest, Alaska. The foreground field of view is slightly more than 1/4 mile wide.

Advance

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.


July 1994 northwest-looking photograph showing part of a push moraine formed by the advance of a spatulate finger of advancing glacier ice, during the 1993-1995 surge of Bering Glacier, Chugach Mountains, AK. Bering Glacier flows through Wrangell-Saint Elias National Park.

A northwest-looking photograph showing the west margin of the Meares Glacier in September 2000, which advanced into the adjacent forest and knocked down a mature Sitka Spruce, Unakwik Inlet, Prince William Sound, Chugach National Forest, Alaska.

Southwest-looking oblique aerial photograph showing a number of glacier valleys separated by angular arete ridges, northeastern Juneau Icefield adjacent to the Alaska - Canada Border, Coast Mountains, Alaska.

Arête

A jagged, narrow ridge that separates two adjacent glacier valleys or cirques. The ridge frequently resembles the blade of a serrated knife. A French term referring to the bones in a fish backbone.


North-looking oblique aerial photograph showing the shadow of an angular arete ridge on the south side of the Bagley Ice Valley, Bering Glacier, Wrangell-Saint Elias National Park, Alaska.

West-looking photograph showing an angular arete ridge, composed of schist, on the upper Taku Glacier, Juneau Icefield, Tongass National Forest, Coast Mountains, Alaska.

| USGS Education | Geology of National Parks |
Maintainer: Mike Diggles
Prepared by Eleyne Phillips

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: http://pubs.usgs.gov/of/2004/1216/a/a.html
Page Contact Information: GS Pubs Web Contact
Page Last Modified: Saturday, January 12, 2013, 11:18:29 PM