OCR A Level GL - 5 OCR A Level GL 2.2 Glossary Flashcards
Ablation
the loss of ice and snow, especially from a glacier, through melting, evaporation and sublimation.
Accumulation
the addition or gain of snow and ice to a glacier over time.
Active layer
the near surface layer in a periglacial environment which seasonally freezes and thaws.
Alases
flat-floored, steep-side depressions in periglacial environments.
Anthropocene
the current geological period where humankind is the main driver of environmental change.
Arête
a narrow, ‘knife-edged’ ridge between two corries.
Aspect
the direction a slope faces
Attrition
the erosion of sediment transported by rivers, glaciers, waves and wind.
Basal flow (sliding/slippage)
As the glacier moves over the bedrock, there is friction. The lower ice is also under a great deal of pressure and this, combined with the friction, results in some melting. The resulting meltwater acts as a lubricant, enabling the ice to flow more rapidly.
Blockfield
a large expanse of boulders strewn across a level surface, often in mountain environments
Compressing flow
the movement of glacial ice down a gentle gradient, during which it thickens.
Corrasion
the scouring and erosion of rock surfaces erosion by sediments transported by rivers, glaciers, waves and wind (also known as abrasion.
Corrie\Cirque\Cwm
An armchair-shaped hollow found on the side of a mountain. This is where a glacier forms.
Cryoturbation
frost churning of layers of regolith in periglacial environments.
Deposition
the laying down of sediment transported by rivers, waves, glaciers and wind, as energy levels decline.
Diagenesis
the process by which snow becomes ice due to compression.
glacial drift
the collective term for all glacial deposits, including till and outwash.
Drumlins
streamlined mounds of glacial drift.
erratic
a rock or boulder that differs from the surrounding rock and is believed to have been brought from a distance by glacial action
Erosion
the wearing away and/or removal of rock and other material by a moving force.
Escarpment
a tilt block forming an extensive upland area, with a short, steep (scarp) slope and a long, gentle (dip) slope.
Esker
a long, sinuous ridge composed of stratified sand and gravel.
Freeze-thaw
a mechanical weathering process caused by water, confined in rock joints, expanding as it freezes, and as a result breaking rocks into smaller particles.
Frost heave
the downslope displacement of soil particles that results from cycles of freeze-thaw.
Gelifluction
the slow, downslope mass flow of saturated regolith resting on a layer of permafrost.
Geomorphic
relating to the formation and shaping of landforms and landscapes by natural processes.
Glacial
a prolonged cold climatic phase lasting for tens of thousands of years and causing continental glaciation in middle and high latitudes.
Glacier mass balance
the difference between the amount of snow and ice accumulation and the amount of ablation occurring in a glacier over one year.
Glacio-fluvial
relating to meltwater from a glacier.
Granular disintegration
the breakdown of rocks by weathering into coarse, granular particles.
Hydration
the breakdown of rocks by cycles of wetting (expansion) and drying (contraction).
Hydrostatic pressure
the pressure exerted by a confined fluid, such as water under or in a glacier.
Ice shelf
a floating sheet of ice permanently attached to a land mass.
ice wedge
develops when water enters a crack in the permafrost and freezes
Ice-contact drift
sediment deposited under or against ice.
Inter-glacial
a period of climatic warming (lasting c.10,000 years) between glacials.
Internal Deformation
Where ice crystals move by orientating themselves in the direction of ice movement allowing the crystals to move past one another
Isostatic changes
changes in the absolute level of the land. They are localised and result from either tectonic activity or the addition or removal of weight from the land.
Jökulhaulps
extreme glacial meltwater outbursts caused by geothermal or volcanic activity beneath glaciers.
Kames
a steep-sided mound of sand and gravel deposited by a melting ice sheet.
Lateral moraine
a ridge of till running along the edge of a glacial valley
Meltwater channel
channel cut by glacial meltwater under, along and in front of an ice margin. Meltwater may flow under hydrostatic pressure within the glacier and the resultant channels will show up-down long profiles. Alternatively, water may flow under gravity. Meltwater channels are recognizable from their anomalous topographic positions and their large size (misfit) relative to the streams that now occupy them
Nivation hollow
a depression formed by freeze-thaw and meltwater transport of weathered rock particles beneath a permanent snow patch.
Ognip
the remains of a collapsed pingo, forming a depression surrounded by circular earth ramparts.
Open system
a type of system whose boundaries are open to both inputs and outputs of energy and matter.
Output
the transfer of energy and/or materials out of a system
Outwash
material deposited by glacial meltwater.
Outwash plain
a flat expanse of glacio-fluvial sediment located beyond an existing or former glacier or ice sheet front
Permafrost
frozen ground that remains frozen for at least 2 consecutive years. It is found in cold climates at either high altitudes or high latitudes where the ground does not thaw completely even in summer
Pingo
a conical ice-cored hill in periglacial environments.
Pressure melting point
the temperature at which ice melts when under pressure.
Proglacial lakes
a body of water impounded in front of a glacier.
Pyramidal peak
an angular, sharply pointed mountain peak which results from corrie erosion.
Recessional moraines
a series of ridges running transversely across a glacial trough.
Regolith
a loose layer of rocky material overlying bedrock.
roche moutonnée
known as sheep rocks, this glacier feature is formed when glacial ice advances over outcrops of bedrock. The side facing the glacier may be polished and smooth, but the downward side is left steep and jagged due to glacial plucking action.
Rock flour
fine material derived from abrasion by a glacier.
Rock glacier
coarse rock particles forming linear accumulations and moving slowly downslope due to the formation and melting of interstitial ice.
Solifluction
the slow flow of fine, water-saturated regolith from higher to lower ground.
Stadial
a sudden and brief period of glacial conditions lasting several hundred years.
Striations
scratches or grooves on rock surface formed by glacial abrasion.
Structure
the physical characteristics of rocks, including their jointing, bedding, faulting, angle of dip etc.
Sublimation
the phase change of water from ice to vapour.
Talik
unfrozen ground that may occur above, below, or within discontinuous permafrost
Talus
a steep, concave debris slope at the foot of a cliff or free-face, comprising angular rock particles (also known as a scree slope).
Terminal moraine
a ridge of till extending across a glacial trough.
Thermokarst
landscape of hummocks and wet hollows resulting from subsidence caused by the melting of permafrost.
Till
unsorted material deposited directly by glacial ice.
Truncated spur
an eroded interlocking spur characterised by having a very steep cliff
Weathering
the in situ breakdown of rocks exposed at, or near, the land surface by physical, chemical and biological processes.
U-shaped valley (glacial trough)
a geological formation characterized by high and steep sides and a rounded or flat valley bottom
