Cold Environments Flashcards
Arêtes
Steep sided knife-edge mountain ridge often marking the edges of a corrie or the watershed between two valleys (troughs)
Esker
A sinuous ridge found running parallel to the pre-existing glacier. It is stratified and composed of sub-rounded and rounded sands and gravels. Found on the floor of a glacial trough. Formed by a fluvioglacial deposition in a meandering sub-glacial river.
Basal Sliding
Large scale and often quite sudden movement of a portion of ice in a glacier usually lubricated by sub-glacial meltwater.
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.
Compressional flow
Thickening of ice (glacier) due to a decrease in the long profile valley floor gradient.
Corries
Enlarged armchair-shaped hollows on a mountainside characterised by a steep backwall and a hollowed-out bowl, occasionally containing a lake (tarn).
Drumlins
Egg-shaped depositional features, often in groups -swarms- resulting from the moulding of sub-glacial -ground- moraine by moving ice over the top
Extensional flow
Stretching or thinning of ice (glacier) in response to an increase in gradient (steep slope)
Fragile environments
Natural environments where processes operate slowly and where ecosystems can be easily harmed and take a long time to recover
Frost heave
Small-scale upwards displacement of soil particles resulting from the freezing and expansion of water just below the ground surface
Frost shattering
Also know as freeze-thaw, a physical weathering process involving alternating freezing and thawing of water in joints and pores within rocks
Glacial surge
Relatively rapid but usually short-term movement of a glacier
Glacial system
Inter-relationships between components in a glacial environment, often subdivided into inputs, processes and outputs
Glacial troughs
Glacially-enlarged river valley characterised by having a broad flat base and steep sided (U-shaped)
Glacier budget
Balance between inputs (accumulation), such as snowfall and avalanches, and outputs (ablation), such as calving and melting
Hanging Valleys
Tributary glacial trough perched up on the side of a main glacial trough and often marked by a waterfall
Ice wedges
V-shaped ice-filled features formed by the enlargement of surface cracks by frost action. In time the cracks will become infilled with sediment
Internal deformation
Small scale inter-and intra-granular movement or deformation of ice crystals in response to gravity and mass
Kames
Mounds or hillocks found on the floor of a glacial trough formed by fluvioglacial deposition, e.g Kame terraces, formed by deposition in a marginal lake
Meltwater channels
Often narrow and steep-sided valleys formed by torrents of meltwater at the end of a glacial period
Moraines
Glacial deposits comprising largely angular and unsorted debris transported on (supraglacial), in (englacial), or under (sub-glacial) the ice. Many types of moraine can be identified, such as lateral (edge of glacier), medial (centre of glacier) and terminal (snout of glacier)
Nivation hollows
Shallow hillside hollow resulting from a concentration of snow-related processes such as frost shattering and slumping
Nivation
Snow-related processes, such as weathering and mass movement, that operate collectively to form shallow hollows in the landscape
Outwash plains
Often vast area of well-sorted and rounded sand and gravel deposits extending for some distance in front of a glacier, carried by meltwater
Patterned ground
Concentration of large stones on ground surface, usually associated with polygonal patterns of ice wedges, often forming stripes on slopes due to gravity
Periglacial
Environments experiencing long cold winters and short warm summers, typically with frozen ground (permafrost) but not covered by ice (glacial)
Permafrost
Permanently frozen soil and rock, a key characteristic of a periglacial environment
Pingos
Ice-cored mounds found in periglacial environments, formed by the freezing of sub-surface water bodies and subsequent swelling of the ground surface
Pyramidal peaks
Remnant of intense glacial erosion taking the form of a very steep-sided isolated peak - 3 or more corries eroding back to back
Rotational flow
Concave or arcuate flow typically experienced in a corrie and responsible for increased erosion (over-deepening)
Solifluction lobes
Extended lobes (tongues) of saturated soil formed by solifluction on a hillside
Solifluction
Gradual downhill slumping of saturated soil and rock, usually in summer when the upper surface zone (active layer) melts and becomes heavy and waterlogged
Truncated Spurs
Former interlocking spurs that have been eroded by a glacier to form a steep valley side
Warm-based glacier
Glacier where the base temperature is high enough to enable meltwater to exist and therefore basal sliding to occur
