Flashcards in Glaciers Deck (17):
what is a glacier
Glaciation is the process or state being covered by ice glaciers or ice sheets.
what is an ice age
An ice age is a long period in time when the Earth’s temperature was reduced resulting in the expansion of continental and polar ice sheets and glaciers. During the last ice age up to 32% of the land area was covered by ice.
what is an ice sheet
An ice sheet is a chunk of glacier ice that covers the land surrounding it and is greater than 50,000 kilometers wide
what is an ice cap
An ice cap covers less than 50,000 square kilometers and usually feeds a series of glaciers around its edges. Ice flows away from this highest point toward the cap’s edges.
what is a corrie
deep bowl shaped landform created by the glacier
what does plucking mean
rocks, stones and debris are pulled out of the ground when the ice freezes to them before the glacier moves on again
what does the term abrasion mean in glacier context
it is the material carried by the glacier scrapes and scours the landscape as the glacier passes.
what is the snout
it is the end of the glacier
what is terminal moraine
material pushed in front of the glacier
what are crevasses
deep cracks in the glacier caused when it moves down the slope.
what is a tarn
a lake that forms in the corrie when the glacier disappears
what is thaw weathering
Water that enters cracks in rocks freezes and when it does, it expands. Repeated freeze and thaw means cracks in the rock expand until the rock is fractured.
what landscapes does glaciation produce (hard)
• Pyramidal peaks
• U-shaped valleys
• Hanging valleys
• Truncated spurs
what is an arête
an arête is a knife-edge ridge. It is formed when two neighbouring corries run back to back. As each glacier erodes either side of the ridge, the edge becomes steeper and the ridge becomes narrower, e.g. Striding Edge found on Helvellyn in the Lake District.
what is a pyramidal peak
A pyramidal peak is formed where three or more corries and arêtes meet. The glaciers have carved away at the top of a mountain, creating a sharply pointed summit.
what is glacial till
Glacial till is unsorted glacial sediment. Till is made up from material eroded by the moving ice of a glacier.