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Antarctica
: Small areas of rock isolated from the main mountains, known as nunataks,
also provide further geological information around the margins of the ice
sheet.
Nunataks are frost shattered peaks that lie above the level of the glacier or ice cap. They are subjected to freeze thaw weathering processes.
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| Talus
or scree slopes are formed as weathered material released by freeze thaw
weathering collects at the base of steep slopes.
If this material falls onto a glacier it becomes part of its load and can be used to aid erosion by abrasion. |
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Rock glaciers are lobate or tongue shaped landforms composed of coarse angular boulder debris with steep lateral flanks and frontal ramp. A distinctive surface morphology of arcuate ridges and furrows is interpreted as reflecting slow rates of internal deformation and flow that is associated with buried ice. | |
| This unglaciated area led to the formation of Felsenmeer, which is essentially exposed rock surfaces that have been broken up by frost action so that much rock is buried under a cover of angular shattered boulders. This principally occurs in Arctic regions and high mountain areas. Their continuity and depth vary with climate, vegetation and rock type. The photo shows an area of Newfoundland, Canada that was like a nunatak - not covered in glacier ice during the Ice Age. |  |
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Patterned ground: Definition: An array of small-scale, geometric features found at the surface of a regolith that has been disturbed by frost action. The group includes circles, polygons, and nets, which normally occur on level or gently sloping surfaces, and steps and stripes which are found on steeper gradients. Both sorted and non-sorted varieties are recognized. The sorted varieties are typically outlined by coarse, stony material, and so are termed 'stone circles', 'stone polygons', 'stone nets', 'stone steps', and 'stone stripes'. | |
| The origin of patterned ground involves a complex interaction of several geomorphological processes, including frost sorting, frost heaving, and mass movementThe photo opposite is of stone polygons. These are periglacial weatherng landforms |  |
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| Some of these
images are a small selection taken from the Geological Survey of Canada
Terrain Sciences gallery and are free to visitors of www.nelsonthornes.com.
There are a further 600 images in this superb resource ranging from a
plethora of glacial and periglacial landforms to fluvial and geological
features.Click on this link to see the rest of the
images: http://sts.gsc.nrcan.gc.ca/tsdsvr/landf_new.asp |
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