Cold Environments Flashcards
Define basal sliding
Large scale and often quite sudden movement of a portion of ice in a glacier usually lubricated by sub-glacial meltwater
Define aretes
Steep-sided knife-edge mountain ridge often marking the edges of a corrie or the watershed between two valleys (troughs)
Define cold-based glacier
Glacier where the base temperature is too low to enable liquid water to be present and where the glacier will probably be frozen to the ground
Define compressional flow
Piling up or thickening of ice due to a decrease in the long profile valley floor gradient
Define a corrie
Enlarged armchair shaped hollows on a mountainside characterised by a steep back wall and a hollowed out bowl, occasionally containing a tarn
Define a drumlins
Egg shaped depositional features often in groups (swarms) resulting from the moulding of sub-glacial moraine by moving ice moving over the top
Define an esker
Sinuous ridges found on the floor of a glacial trough formed by fluvioglacial deposition in a meandering sub glacial river
Define extensional flow
Stretching or thinning of ice in response to an increase in gradient
Define fragile environments
Natural environments where processes operate slowly and where ecosystems can be easily harmed and take a long time to recover
Define froze heave
Small-scale upwards displacement of soil particles resulting from the freezing and expansion of water just below the ground surface
Define frost shattering
Also known as freeze that a physical weathering process involving alternating freezing and thawing of water in joints and pores within rocks
Define glacial surge
Relatively rapid but unusually short term movement of a glacier
Define glacial system
Inter-relationships between components in a glacial environment often sub divided into inputs processes and outputs
Define hanging valley
Tributary glacial trough perched up on the side of a main glacial trough and often marked by a waterfall
Define ice wedge
V shaped ice filler feature formed by the enlargement of surface cracks by frost action. In time the cracks will become in filled with sediment
Define internal deformation
Small scale inter and intra granular movement or deformation of ice crystals in response to gravity and mass
Define kames
Mounds or hillocks found on the floor of a glacial trough formed by fluvioglacial deposition, e.g. Kame terraces formed by deposition of a marginal lake
Define meltwater channels
Often narrow and steep sided valleys formed by torrents of meltwater at the end of a glacial period
Define moraines
Glacial deposits comprising largely angular and unsorted debris transported on (supra glacial) and in (englacial) or under (sub glacial) the ice. Many types of moraine can be identified such as lateral, medial and terminal
Define nivation hollows
Shallow hillside hollow resulting from a concentration of snow related processes such as frost shattering and slumping
Define nivation
Snow related processes, such as weathering and mass movement that operate collectively to form shallow hollows in the landscape
Define out wash plain
Often vast areas of well sorted and rounded sand and gravel deposits extending for some distance I. front of the glacier carried by meltwater
Define patterned ground
Concentration of large stones on the ground surface usually associated with polygonal patterns of ice wedges often forming stripes on slops due to gravity
Define periglacial
Environments experiencing long cold winters and short war. Summers typically with frozen ground but not covered by ice
