glaciers 2 Flashcards
(33 cards)
glacier
A large, perennial accumulation of crystalline ice, snow, rock, sediment, and often liquid water that originates on land and moves down slope under the influence of its own weight and gravity
Glaciation
The formation, movement, and recession of glaciers
Zone of Accumulation
The area where snow input exceeds ice output
Ice sheet
A large area of ice covering more than 50000kmsq
valley glacier
A glacier that is found in a valley
Firn/Névé
Snow and ice that have settled and compacted over time forming the precurser to glacial ice
zone of ablation
The area where ice output exceeds snow input
Glacial budget
The difference between accumulation and ablation, determining whether a glacier advances or retreats
Mass balance
The difference between accumulation and ablation, detremining whether a glacier gains or loses mass
Equilibrium line
The boundary between the zone of accumulation and zone of ablation where their is no net gain or loss
Calving
the process where large chunks of ice break off a glacier and enter the sea or a lake
Plucking
A type of glacial erosion where rocks are frozen to the base of a glacier and then torn away as the glacier moves
Abrasion
a type of glacial erosion where the wears away the bedrock as it moves with the smaller fragments smoothen the rocks while the larger fragment make deep grooves called striations
Basal sliding
The process where a glacier slides over its bed due to meltwater acting as a lubricant
Meechanical (freeze-thaw) weathering
Water enters joints and cracks in rocks. On freezing the ice expands by 10% putting pressure on the rock. Continual freeze-thaw weathering leads to the cracks widening and pieces of rock shattering off from the main rock
Lateral moraine
Material deposited along the sides of a glacier, often forming a ridge when the ice melts
Medial moraine
Formed when two glaciers merge, the lateral moraines from the two glaciers combine to create a ridge in the middle of the larger glacier
Terminal moraine
Material deposited at the snout of a glacier, marking the furthest extent of the ice advance
recessional moraine
formed when a glacier retreats and pauses, depositing material at the new end of the glacier
ground moraine
material deposited beneath the glacier as it moves forming a blanket of till on the valley floor
Corrie (Cirque) (Cwm)
A bowl-shaped, steep-sided depression at the head of a glacial valley
U-Shaped Valley
A valley with a broad flat floor and steep sides carved uniformly by the glacier as it moves downslope
Hanging Valley
A smaller valley that joins a larger, deeper glacial valley at a higher elevation. The contrast in depth often results in waterfalls or cascades from the hanging valley into the central valley.
