Glaciers Flashcards
How does a Kame form?
As meltwater streams emerge onto the outwash plain or proglacial lake at the glacier snout, their velocity suddenly falls and sediment is deposited.
How does a kame terrace form?
During the summer, The Valley sides rádiate heat, melting the edges of the glacier and forming meltwater streams, when the glacier retreats, the sediment will fall forming a kame terrace.
How does an Esker form?
Sub glacial streams carrying rock debris meander beneath the glacier. When the glacier retreats, the debris load is deposited at a consistent rate and forms a ridge.
Name 3 ice contact features?
Kame
Kame Terrace
Esker
Name 4 proglacial features?
Outwash plain (sandur)
Kettle Hole
Proglacial Lake
Meltwater channel
How does an outwash plain form?
Meltwater streams emerge from glaciers and enter lowland areas. Here they lose their energy and deposit their debris load.
How does a kettle hole form?
As the glacier retreats, detached blocks of ice remain on the outwash plain. Meltwater flows over this ice and deposits fluvioglacial debris. Eventually the ice melts and and the debris subsided and forms a depression, which often fills with water.
How does a proglacial lake form?
Formed by the damming action of terminal or recessional moraines during the retreat of a melting glacier. Can also be formed by meltwater trapped against an ice sheet as a result of isotatic depression.
How does a meltwater channel form?
Melt water can erode deep channels even gorged as a result of high hydrostatic pressure. They can flow uphill because of this pressure (under the glacier)
What is lodgement till?
A process that occurs beneath the i e mass when subclavian debris that was being transported becomes lodged or stuck on the glacier bed.
When does a medial moraine form?
When lateral moraines from two merging glaciers join up leaving a line of debris in the centre of the combined glaciers flow. As combined glaciers melt, the medial moraine is deposited to form a low ridge
What is a lateral moraine?
A high and nearly symmetrical ridge formed along the outer edge of a glacier, can be several metres high. Formed from freeze thaw on The Valley sides that causes the material to fall onto the edge of the glacier below.
Recessional moraines?
When a secondary ridge forms at the snout. Can commonly appear as a line of hills but does dot mark the full extent of the ice.
What is a terminal moraine?
Ridge is sediment piled up at the suggest extent of an advancing glacier. Commonly appears as a line of hills due to the erosive action of meltwater streams from retreating glacier.
How does a cirque form?
A large round sided hollow on a mountainside is eroded and deepened by plucking and abrasion due to the rotational ice movement of a cirque glacier.
How does an Arête form?
Plucking and abrasion of the back wall of 2 cirques on a mountain side means that they erode backwards towards one another, creating a narrow ridge. Also involves freeze thaw.
How does a pyramidal peak form?
Erosiónala processes within nearby cirques mean that they erode backwards towards each other creating a sharp pointed mountain summit. Plucking is important.
How does a glacial trough occur?
A V shaped river valley is widened and deepened as a result of powerful plucking and abrasion by a valley glacier which goes through the landscape rather than around it.
How do truncated Spurs form?
Valley glaciers less flexible than rivers and remove the ends of interlocking spurs by plucking and abrasion as they move down the river valley
How does a hanging valley form?
Powerful thicker glacial ice in the main glacial trough is eroded vertically downwards more rapidly than thinner ice or rivers in tributary valleys. The floor of the tributary valleys are left high above the main floor.
How does a ribbon lake form?
Areas of increased plucking and abrasion by The Valley floor deepen part of The Valley floor as a result of either the confluence of glaciers or weaker rocks. Sometimes the lake forms behind a terminal moraine after glaciation.
How does a Roche Moutonnee form?
A more resistant rock outcrop causes ice movement by creep and regelation around it. As the ice slides across the rock, it scours and smoothed the stoss, while refereeing on the lee causes plucking.
How does a knock and lochan form?
Scouring at the base of a glacier excavates areas of weaker rock, forming hollows that fill with meltwater following ice retreat
How does a crag and tail form?
A large mass of hard rock is resistant to ice scouring and creates a steep stoss. Reduced glacier velocity on the lee protects softer rock and allows deposition but the sheltering effect diminishes with distance, creating a sloping tail.
