| Term: | Rock glacier |
| Definition: |
A glacier-like landform that often heads in a cirque and consists of a valley-filling accumulation of angular rock blocks. Rock glaciers have little or no visible ice at the surface. Ice may fill the spaces between rock blocks. Some rock glaciers move, although very slowly.
Looks like a mountain glacier and has active flow; usually includes a poorly sorted mess of rocks and fine material; may include: (1) interstitial ice a meter or so below the surface ('ice-cemented'), (2) a buried core of ice ('ice-cored'), and/or (3) rock debris from avalanching snow and rock. NSIDCCryosphere A mass of rock fragments and finer material in a matrix of ice, showing evidence of past or present flow. IHPGlacierMassBalance A mass of rock fragments and finer material, on a slope, that contains either interstitial ice or an ice core and shows evidence of past or present movement IPAPermafrost A mass of rock fragments and finer material, on a slope, that contains either interstitial Ice or an Ice core and shows evidence of past or present movement. It is a cryogenic landform, supersaturated with Ice that if active, moves down slope by the influence of gravity which produces Creep and deformation of the Mountain Permafrost. Rock Glaciers do not form where there is insufficient moisture to form the interstitial Ice that permits movement of the mass. Some are believed to have been formed, at least partly, by burial of Glacier Ice. Active Rock Glaciers possess steep fronts with slope angles greater than the angle of repose. Rock Glaciers are said to be inactive when the main body ceases to move. Most Rock Glaciers have transverse ridges and furrows on their surface. In general, Rock Glaciers present a lobate shape with surficial morphology similar to a lava flow. However, especially in the central Andes, the morphologies can be considerably complex with multiple basins contributing material and the superposition of two or more lobes. TrombottoGeocryology Rock glaciers are not strictly glaciers, but a flow phenomen in permafrost. A mixture of rock debris interspersed with ice in cavities slowly moves downhill (typically much slower than a glacier). Swisseduc Lava stream like debris mass containing interstitial ice; Movement is primarily due to debris mass under the influence of gravity, and not due to ice flow patterns; Not a debris covered glacier, but permafrost phenomenon; A glacier-shaped mass of angular rock in a cirque or valley either with interstitial ice, firn and snow or covering the remnants of a glacier, moving slowly downslope. (WGMS 1970); A glacier-shaped mass of angular rock in a cirque or valley either with interstitial ice, firn and snow or covering the remnants of a glacier, moving slowly downslope. If in doubt about the ice content, the frequently present surface; firn field should be classified as 'Glacieret and snowfield' (WGMS 1977); Lava stream like debris mass containing ice in several possible forms and moving slowly down slope (WGMS 1998); A debris covered glacier is not necessarily a rock glacier. To distinguish between rock glaciers and debris covered; glaciers the parameter group 'Debris coverage of tongue' is offered. GLIMSGlacier GCW |