Formations Flashcards
Formation of a hanging valley
Formed from different erosion rates between the tributary valley and the main valley floor. The tributary valley floor erodes and deepens slower than the main valley floor. The difference in the depth increases over time and the tributary valley hangs above the main valley.
Formation of a kame
Mounds of sediment deposited along the front of slowly moving or stationary glaciers. Sediment consists of sand and gravel and builds into mounds. As the ice melts more sediment is deposited on top of old debris
Formation of an esker
Winding sinuous ridges of coarse sand and gravel deposited by meltwater. Winding due to the meandering of the meltwater stream. Can be formed at the base of the ice of surrounded by ice in a tunnel. When meltwater reduces in winter more material is deposited and only exposed when the glacier melts.
Formation of pingos
Formed of the site of a lake in filled with Sediment. The sediment insulates the ground beneath it allowing water to collect. The sediment them freezes so the water is more confined as the pressure increases. The water then freezes and expands pushing the sediment above it upwards to form a pinto mound.
Formation of kettle holes
Blocks of ice are separated from the main retreating glacier. The isolated blocks of ice can become partially buried within meltwater sediment. The ice then melts forming holes or depressions that will be filled with water forming kettle hole lakes.
Formation of kame terrace
Formed from sediment that is made of sand and gravel. Formed along the sides of glaciers or formed by the meltwater streams the flow along the side of the ice, trapped by valley walls. When the valley walls warm up in summer they melt the ice nearest to them, forming a glacial trough.
Formation of drumlins
Formed by deposition, the glacier can’t carry all of the moraine through the lower course so some has to be deposited. The long shape is due to the direction of the moving ice as the blunt end faces the oncoming ice. Obstacles within the path of the glacier encourage the elongated shape.
Formation of pyramidal peak
3 or more corries eroding back to back forming and isolated peak called a pyramidal peak.
Formation of a corrie
And enlarged hollow on a mountainside. Nivation processes such as slumping and weathering enlarge the hollow on the mountainside. Plucking forms a craggy back wall. Abrasion scoops out the hollow, rotational slip leads to intense abrasion. A rock lip is formed from thinner ice that is less erosive.
Formation of an arête
2 neighbouring glaciers cutting back into a mountainside. Each one eroding a corrie. The ridge between the 2 glaciers becomes narrowed forming a knife edge ridge called an arête.
Fjord
Glacial troughs that were flooded by the sea when it rose at the end of the ice age. Glaciers stretched further out to sea during the ice age as the sea levels were lower. This means the trough now extends below sea level. Skerry small island at the mouth formed by rotational slip.
Crag and tail
Consists of large mass of resistant rock on the stoss (upslope side) and gently sloping tail (lee side) of less resistant rock. The force of the glacier erodes the surrounding softer material, leaving a rocky block petruding. Result from abrasive base of glacier sliding on land surface. A tail is softer rock, crag serves as a potential shelter from a glacier. Often the rail has been removed by glacial erosion.
Nivation hollow
Depressions on the hillside that are enlarged by nivation processes. Intensive freeze thaw and frost shattering activity around the edges of the snow. In summer meltwater removed weathered rock debris. Hollow continues to grow if material is removed and freeze thaw can continue.
