Glacial Landscapes Flashcards
1
Q
What is a glacier (3)?
A
- a slow-moving river of ice
- mimic fluvial landscapes
- form in locations with permanent ice
2
Q
How do glaciers form (2)?
A
- formed from the continual accumulation of ice which is recrystallized under subsequent accumulations of snow above it
- glaciers move very slowly downslope under the pressure of their own weight and gravity
3
Q
Where are glaciers located (3)?
A
- high elevations and high latitude locations
- 11% of Earth’s surface is covered by glaciers
- most are located at high latitudes
4
Q
Where are alpine glaciers located?
A
mountainous environments
5
Q
What are the three types of alpine glaciers?
A
- valley glacier: forms in the mountains and flows downslope
- piedmont glacier: forms when a valley glacier empties out into a flat space
- tidewater glacier: ends in a body of water; results in calving
6
Q
What are continental glaciers (3)?
A
- continuous masses of ice known as ice sheets
- most of Earth’s glacial ice is locked in ice sheets
- most of Greenland is covered by continental ice sheets
7
Q
What are the two glacial zones and the line that divides them?
A
- accumulation zone: where snowfall and moisture collects and compacts into ice
- ablation zone: where a decrease in the size of the glacier occurs through melting, sublimation, and calving
- equilibrium line: the boundary between the two zones
8
Q
What is glacial mass balance (4)?
A
- whether or not the glacier is expanding or retreating
- accumulation > ablation = expanding glacier
- accumulation < ablation = retreating glacier
- always moving regardless of mass balance
9
Q
What is glacial movement (3)?
A
- bottom of glacier more malleable; surface of glacier more brittle
- basal slip: the difference in the speed at which the glacier is moving
- crevass: vertical crack which develops in glaciers; can be very deep and covered in a thin layer of ice
10
Q
What is the shape of a preglacial valley?
A
V-shaped
11
Q
What is the shape of a glacial valley?
A
U-shaped
12
Q
What is glacial abrasion (3)?
A
- mixture of ice and rocks travelling within the glacier which scours out the canyon walls
- striation: a very long scratch created on the side of the valley caused by glacial abrasion
- plucking: occurs when larger rocks are pulled from the bedrock by the glacier
13
Q
What are the seven elements of a postglacial valley?
A
- U-shaped valley
- cirque: bowl-shaped features which form at the top of a glacier
- arête: very sharp ridgeline that forms when two cirques erode against each other
- col: dip within an arête caused by another glacier
- horn: pyramid-shaped peak formed when multiple cirques erode into each other
- hanging trough: smaller tributary glacier which did not erode down to the same level as the main glacier
- hanging waterfall: forms within a hanging trough
14
Q
What are six feartures which can be formed by glaciers?
A
- glacial erratics: rocks picked up by glacier as it moved downslope and dropped in place
- talus slope: can form in conjunction with glacial activity along valley wall
- tarn: small lake which forms in a cirque
- paternoster lake: a series of lakes linked together; formed with rocks with different resistance to erosion
- rouche mouronne: assymetrical hill consisting of exposed bedrock modified by glacial activity
- fjord: form when glacier moves all the way down to the coast and ocean water floods valley floor
15
Q
What is glacial drift (3)?
A
- all glacial deposits
- till: further from glacier; unsorted and unstratified
- outwash: closer to glacier; sorted and stratified
