Types of glaciers

Glaciers can be classified according to their shape, area/altitude distribution, temperature, movement or location. Definitions of some typical glaciers follow:

 

Cirque glaciers: Glaciers that occupy depressions in mountains and are typically wider than their length.

Cirque glacier in Mt. Sauðhamarstindur. Photo: Jóhannes Baldvin Jónsson, July 26th 2005.

Cirque glacier in Mt. Sauðhamarstindur. Photo: Jóhannes Baldvin Jónsson, July 26th 2005.

 

Debris-covered glacier: Surface debris suppresses melt rates when it is thicker than a few cm. If continuous debris cover is present, ablation rates can be significantly reduced. Hrútárjökull is a classic example of a debris-covered glacier.

Close up of the debris covered snout of Rjúpnabrekkujökull outlet glacier. Photo: Snævarr Guðmundsson, 2010.

Close up of the debris covered snout of Rjúpnabrekkujökull outlet glacier. Photo: Snævarr Guðmundsson, 2010.

 

Glacieret or snowfield: Very little ice mass, virtually no ice movement and accumulation and ablation areas not always detectable.

Small glacieret on Kjósareggjar mountain. Photo: Snævarr Guðmundsson, September 13th 2014.

Small glacieret on Kjósareggjar mountain. Photo: Snævarr Guðmundsson, September 13th 2014.

Hofsjökull eystri glacier. Photo: Snævarr Guðmundsson, 2006.

Hofsjökull eystri glacier. Photo: Snævarr Guðmundsson, 2006.

 

Hanging glaciers: When a valley glacier shrinks and retreats, tributary glaciers are sometimes left in side valleys high above the central glacier. An example is Birkidalsjökull east of Morsárjökull.

Birkidalsjökull (far right) is a hanging glacier, which previously was connected with Morsárjökull outlet glacier. Photo: Matthew J. Roberts, 2007.

Birkidalsjökull (far right) is a hanging glacier, which previously was connected with Morsárjökull outlet glacier. Photo: Matthew J. Roberts, 2007.

 

Ice aprons: Small steep glaciers clinging high on mountain sides. Several glaciers of these types are located close to Þverártindsegg, in Jökulgil, Tungutindar and elsewhere within Vatnajökull National Park.

Small aprons in Mt. Jökulsgilstindar Photo: Oddur Sigurðsson, September 28th 2002. 

Small aprons in Mt. Jökulsgilstindar. Photo: Oddur Sigurðsson, September 28th 2002.

 

Ice cap:  Dome-shaped ice mass, less than 50.000 km2 in area, with radial flow and usually centered on the highest point in a landscape. Ice caps primarily form in polar and sub-polar regions. The five main glaciers in Iceland, Vatnajökull, Hofsjökull, Langjökull, Mýrdalsjökull and Drangajökull, are all ice caps.

MODIS satelite image of Iceland showing the largest ice caps. Source: https://terra.nasa.gov/about/terra-instruments/modis.

MODIS satelite image of Iceland showing the largest ice caps. Source: https://terra.nasa.gov/about/terra-instruments/modis.

 

Ice fall: Usually a part of a glacier where ice flows down very steep bedrock. As a result, the surface is fractured and heavily crevassed. Morsárjökull, Svínafellsjökull and Falljökull glaciers fall down from high elevation.

Ice fall of Morsárjökull. Photo: Guðmundur Ögmundsson, March 29th 2012.

Figure text 8b: Ice fall of Morsárjökull. Photo: Guðmundur Ögmundsson, March 29th 2012.

 

Icefield: A large ice body that covers mountainous terrain but is not thick enough to obscure the subsurface topography. Its flow is therefore not predominantly radial as in a dome-shaped ice cap.

The Southern Patagonian icefield from space. Source: NASA Earth Observatory.

The Southern Patagonian icefield from space. Source: NASA Earth Observatory.

 

Ice sheet: A large expanse of ice unconstrained by topography and continental in size, or larger than 50 000 km2 (e.g. the Antarctic and Greenland Ice Sheets).

Satellite image of Antarctica. Source: NASA blue marble data set.

Satellite image of Antarctica. Source: NASA blue marble data set.

 

Ice shelve: Floating mass of ice fed by tributary glaciers, sometimes also nourished by snow fall and bottom freezing. The limit where it loses contact with the coast or land is called grounding line. Ice shelves surround most of the Antarctic continent. Floating ice shelves cover the subglacial lakes at Grímsvötn and the Skaftá cauldrons in Vatnajökull. The frontal part of Breiðamerkurjökull also floats and forms a small ice shelf.

The ice shelf in Grímsvötn. Photo: Hrafnhildur Hannesdóttir, June 7th 2010.

The ice shelf in Grímsvötn. Photo: Hrafnhildur Hannesdóttir, June 7th 2010.

 

Ice stream: Fast-moving part of an ice sheet where the ice velocity is higher than in the surrounding ice mass. Ice streams transport great amounts of ice to the ocean. They are found in Greenland and Antarctica.

Byrd icestream in Antarctica. Source: USGS/Landsat.

Byrd icestream in Antarctica. Source: USGS/Landsat.

 

Niche glaciers: Glaciers that develop in small gullies or depressions.

 

Outlet glacier: Glacier that flows from an ice sheet, ice cap or icefield, and typically follows topographic depressions such as valleys. Vatnajökull ice cap is composed of ice domes from which about 40 outlet glaciers flow.

Aerial view of Öræfajökull, Kotárjökull outlet glacier in the middle of the photo, Mt. Rótarfjallshnúkur is a high point of the caldera rim. Photo: Snævarr Guðmundsson, 2006.

Aerial view of Öræfajökull, Kotárjökull outlet glacier in the middle of the photo, Mt. Rótarfjallshnúkur is a high point of the caldera rim. Photo: Snævarr Guðmundsson, 2006.

 

Piedmont glacier: Valley glacier that spills into relatively flat plains where it spreads out into a bulb-like lobe. Skeiðarárjökull and Múlajökull in Hofsjökull ice cap are classified as piedmont glaciers

Skeiðarárjökull outlet glacier MODIS satellite image from 4th of August 1999.

Skeiðarárjökull outlet glacier MODIS satellite image from 4th of August 1999.

 

Rock glaciers: Geological formations created from slow-moving, debris-covered ice, often found in steep-sided valleys. They may also form when frozen soil creeps downslope. The ratio of rock to ice favours the rock. Rock glaciers are typically found in Tröllaskagi peninsula.

 

Tidewater glacier: Glacier that reaches out into the sea, often with calving icebergs. Breiðamerkurjökull calves into lake Jökulsárlón which is mixed with sea water.

Aerial view of Jökulsárlón glacial lake and Breiðamerkurjökull outlet glacier. Photo: Oddur Sigurðsson, September 28th 2002.

Aerial view of Jökulsárlón glacial lake and Breiðamerkurjökull outlet glacier. Photo: Oddur Sigurðsson, September 28th 2002.

 

Valley glacier: glaciers commonly originating from mountain glaciers or icefields that flow down valley, have a clearly defined accumulation area, and limited by the topography. Several outlet glaciers of Öræfajökull are typical valley glaciers.

Virkisjökull and Falljökull outlet glaciers. Photo: Snævarr Guðmundsson, August 17th 2006.

Virkisjökull and Falljökull outlet glaciers. Photo: Snævarr Guðmundsson, August 17th 2006.