Glaciation Key Terms Flashcards
What is Ablation?
The process of melting and sublimation by which a glacier loses ice and snow.
What is Accumulation?
The process of snow and ice being added to a glacier, primarily through snowfall.
What is the Active Layer?
The top layer of soil above permafrost that thaws in summer and refreezes in winter, allowing limited biological activity and geomorphic processes.
What is Albedo?
A measure of how much sunlight a surface reflects, ranging from 0 (no reflection) to 1 (total reflection). Surfaces like ice and snow have high albedo, while darker surfaces have low albedo.
What is an Arête?
A sharp knife-edged ridge formed between two glacial corries.
What is Basal Crushing?
The process where rock fragments at the glacier base are ground down by the weight and movement of the ice, producing fine rock flour.
What is Basal Melting?
The melting of ice at the base of a glacier caused by geothermal heat and pressure melting, which contributes to basal sliding.
What is Bed Deformation?
When soft sediments beneath a glacier deform and flow, allowing the overlying ice to move more easily.
What is a Bergschrund?
A crevasse that forms between the moving glacier ice and the stationary ice or firn above it.
What are Braided Rivers?
River channels that split and rejoin multiple times, typically found in meltwater-dominated environments.
What is Continuous Permafrost?
A thick, unbroken layer of frozen ground found in the coldest regions, where the ground remains frozen year-round.
What is a Corrie (Cirque or Cwm)?
A bowl-shaped hollow with a steep back wall, formed by glacial erosion and freeze-thaw weathering, often holding a tarn.
What is Crag and Tail?
A resistant rock (crag) protects softer material behind it, forming a tapering ridge (tail).
What is a Crevasse?
A deep open crack that forms in a glacier due to differential movement.
What is the Cryosphere?
The portions of the Earth’s surface where water is in solid form, including ice sheets, glaciers, ice caps, sea ice, snow cover, and permafrost.
What is Discontinuous Permafrost?
Areas where permafrost occurs in patches, interspersed with unfrozen ground, due to slightly warmer conditions.
What is a Drumlin?
Streamlined, elongated hills of glacial till, formed beneath a glacier and indicating the direction of ice flow.
What are Erratics?
Large rocks or boulders transported and deposited by a glacier far from their source region.
What is an Esker?
Long, winding ridges of sand and gravel deposited by meltwater rivers under a glacier.
What is Firn?
Compacted, granular snow that has undergone partial melting and refreezing but has not yet transformed into glacial ice.
What is a Fjord?
A glacial trough flooded by rising sea levels after ice has melted.
What is Freeze-Thaw Weathering?
The breakdown of rock caused by the repeated freezing and thawing of water within cracks or pores in the rock.
What is Frost Heave?
The upward swelling of soil due to the formation of ice lenses during freezing conditions.
What is Glacial Till?
Unsorted sediment deposited directly by glacial ice.
What is a Glacial Trough (U-shaped Valley)?
A valley widened and deepened by glacial erosion, with steep sides and a flat floor.
What are Ground Contraction / Patterned Ground / Stone Polygons?
Circular or polygonal surface patterns formed by freeze-thaw cycles and soil movement.
What is Ground Ice / Ice Wedges?
Large masses of underground ice, including vertical ice wedges formed when water enters cracks and freezes.
What is a Hanging Valley?
A smaller tributary valley left high above the main glacial trough, often creating waterfalls.
What is Intergranular Movement?
The internal shifting of ice crystals past one another within a glacier, allowing the ice to deform and flow.
What is a Kame?
Mounds or ridges of sorted sand and gravel deposited by meltwater in hollows or as fans.
What are Kettle Holes?
Small depressions or hollows formed by melting blocks of ice left in outwash plains.
What is Laminar Flow?
The movement of glacier ice in parallel layers with minimal mixing, typical of slower, more stable ice flow.
What are Loess (Aeolian Deposits)?
Wind-blown deposits of fine, silt-sized sediments, often derived from glacial outwash plains.
What are Milankovitch Cycles?
The collective effects of changes in the Earth’s movements on its climate over thousands of years.
What is a Moraine?
Accumulations of glacial till that have fallen onto the glacier surface or have been plucked and pushed along by the glacier as it moves.
What is Névé?
Young, granular snow that has been partially melted, refrozen, and compacted. It forms the surface layer of a glacier.
What are Nivation Hollows?
Depressions formed under patches of snow due to freeze-thaw and meltwater erosion.
What are Overflow Channels?
Valleys formed when glacial lakes overflow, carving out new drainage paths.
What is Permafrost?
Ground that remains completely frozen for at least two consecutive years.
What is a Pingo?
Ice-cored hill formed by the freezing of water in the ground, pushing up the surface.
What is Plucking?
A process of glacial erosion where meltwater freezes around rocks and pulls them away as the glacier moves.
What are Positive Feedback Loops?
Processes that cause self-sustaining changes within the glacial system.
What is the Pressure Melting Point?
The temperature at which ice melts under pressure, decreasing as pressure increases.
What is a Pyramidal Peak?
A pointed mountain peak formed where three or more corries erode back towards each other.
What are Regelation and Creep?
Regelation: The process where pressure causes ice to melt on the upstream side of an obstacle, then refreezes on the downstream side. Creep: The deformation of ice around obstacles under the glacier.
What is a Ribbon Lake?
A long, narrow lake formed in a glacial trough where over-deepening has occurred.
What is a Roche Moutonnée?
A rock formation created by glacial abrasion on the up-valley side and plucking on the down-valley side.
What is a Sandur (Outwash Plain)?
Extensive flat areas of sediment deposited by meltwater streams in front of a glacier.
What are Scablands?
Barren, rocky landscapes formed by meltwater floods eroding glacial sediments and bedrock.
What is Slippage?
The movement of a glacier as the entire ice mass slides over the bedrock due to meltwater lubrication at the base.
What is Solifluction?
The slow downslope flow of saturated soil over impermeable permafrost.
What is Sporadic Permafrost?
Isolated pockets of permafrost found in otherwise thawed ground.
What are Stone Stripes, Debris Fields?
Surface features formed by repeated freeze-thaw cycles breaking up and moving rocks.
What are Striations?
Scratches or grooves etched into bedrock by rocks embedded in moving glacier ice.
What is Sublimation?
When ice transitions directly from a solid state to a gas state without passing through the liquid state.
What is a Truncated Spur?
Former interlocking spurs in a V shaped river valley that have been cut off and eroded away by a glacier.
