Geography Glaciers Nov 2017 Flashcards
What is a glacier?
A glacier is a slow moving river of ice.
What is it called when a glacier grows?
Accumulation.
How does accumulation happen?
Accumulation happens when there are more inputs than outputs.
Ablation is when a glacier ……..
Retreats.
How does a glacier retreat?
A glacier retreats when there are more outputs than inputs.
How do glaciers originate?
Glaciers originate from heavy precipitation.
Snow initially has ……… between the flakes
Air.
The weight of the new snow ……….. it all squeezing out the air between them
Compacts.
What are the 4 steps of Corrie formation?
- Snow accumulates in a hollow (normally facing north/north-east). Overtime the snow is compacted and forms ice.
- Freeze-thaw and plucking creates a steep back wall. Due to water causing rotational slip, the hollow gets deeper from abrasion.
- When the glacier melts it deposits moraine at the end of the Corrie creating a rock lip. The Corrie fills with water creating a Corrie lake to tarn.
- If 2 corries form back to back an arête is formed and if 3 or more corries form back to back a pyramidal peak is formed.
This compaction causes some of the snow to become …….
Ice.
What are the 4 glacial landforms?
Glacial trough, hanging valley, truncated spur a and ribbon lake.
How are truncated spurs formed?
Ice falls from corries at the start of the valley. It falls into a V shaped valley with interlocking spurs. The rivers used to wind around these, but solid ice cannot. Therefore it uses abrasion and its load and erodes the interlocking spurs away, bulldozing the material down the valley to cut off the interlocking spurs creating truncated spurs.
How is a glacial trough formed?
Glacial troughs form in V shaped valleys. During the ice age it filled with a large glacier. The glacier deepens, straightens and widens the valley with abrasion and plucking. The valley is now U shaped with a wide valley floor and steep sides.
How are hanging valleys formed?
Hanging valleys are formed when there are different rates of erosion between the main glacier and tributary glaciers. The floors of the tributary valleys are eroded at a slower rate than the main valley. This means the difference between the height of both valleys increases over time.
How is a drumlin formed?
Drumlins are formed by moraine being deposited because of an obstruction causing an increase in friction or a slowing of the glacier. Most of the moraine is deposited at one end of the drumlin with the rest tapering over to its thin end. The flow of ice over this then shapes it into the characteristics of a drumlin.
