Yr10 Glacial Landscapes Flashcards
What is a glacier?
A mass of ice that moves slowly downhill found in cold regions
What are the 3 layers of a glacier?
Fresh snow at top
Old snow (granular and firm ice)
Glacial ice
What are the 2 zones of a glacier?
- Accumulation zone (more snow added to the glacier)
- Ablation zone (where snow melts)
Define ice age
A period of long tern cooling of earth’s atmosphere, resulting in an expansion of ice sheets and glaciers
What are the cooler and warmer periods within an ice age called?
Cooler periods: glacials
Warmer periods: interglacials
When was the most recent ice age and what was it called?
The pleistocene, 2 million years ago
What are the 2 types of erosion carried out by glaciers?
Abrasion and plucking
How is abrasion carried out by glaciers?
Sandpaper effect of rocks frozen to base of glacier smooths surface
Scratches caused by large rocks are called striations
How is plucking carried our by glaciers?
- meltwater beneath glacier freezes and bonds to rocks
- when glacier moves, loose rocks are plucked away, leaving a jagged surface
What are the 3 main ways a glacier moves?
- basal slip
- rotational slip
- Internal deformation
How does a basal slip work?
Meltwater acts as a lubricant to glacier, allowing it to move downhill.
Can be quite sudden and occurs more often during summer
How does a does a rotational slip work in glaciers?
Ice moves along curved surface to enlarge and develop hollows
How does internal deformation work on a glacier?
- weight of ice and influence of gravity causes individual ice crystals to change shape in a plastic like way
- causes glacier to slowly move downhill
What are corries and where are they found?
A deep depression found in the upper course of a glacier
- often have a steep back wall and usually a lake called a tarn
- usually have a raised lip at front
- sometimes referred to as cirque of cwm
How are corries formed?
- snow accumulates in a hollow and is compressed into ice (slope is usually north facing)
- glacier get larger and starts to move
- plucking steepens back wall and abrasion + rotational slips deepens hollow
- rate of erosion at front of glacier lower due to thinner ice
- After melting, corrie is created, with scree slope at back that still freeze-thaws in winter
What are arêtes and how do they form?
- a knife edge ridge with steep drop on either side
- form when erosion in 2 back to back corries causes land between them to narrow
What are pyramidal peaks and how do they form?
- sharp peaks formed when 3 or more corries develop on all sides of a mountain
- ass corries erode towards each other, arêtes are formed
- they then combine to make a pyramidal peak
What are hanging valleys and how are they formed?
- a tributary valley that is higher than the main valley of the glacier
- formed when a smaller tributary glacier flows from valley sides towards main glacial valley
- as glaciers flow through the rock on valley sides, they erode smaller tributaries onto the sides, leaving ‘hanging valleys’
What are truncated spurs and how do they form?
- blunt ended sloping ridges which descends from thr flank of the valley
- formed by glaciers bulldozing any obstacles in glacial Valley, including interlocking spurs, leaving them with blunt edges
What are ribbon lakes and how do they form?
- a long narrow lake in a glacial trough
- formed after glacier melts in an area of softer rock where glacier has eroded deeper. Meltwater sits in this depression, leaving ribbon lake
What is a glacial trough and how does it form?
- before glaciation, a river valley is v shaped
- during Glaciation, rock in the valley sides is removed through plucking and abrasion
- results in a ‘u’ shaped glacial trough with very steep sides and straight wide valley sides
What are moraines?
Piles of deposited rock by a glacier
What are the 5 main types of moraine?
- ground
- lateral
- medial
- terminal
- recessional
What are ground moraines?
Material dragged under glacier which is left behind when glacier melts
What are lateral moraines?
As glacier moves down, scrapes down sides and makes it steeper, forms due to mass movement. Made of scree
What are medial moraines?
Where 2 glaciers merge, and lateral moraines come together to form medial moraine.
Leaves a ridge in the middle after melting
What are terminal moraines?
Material deposited at snout of glacier. Big build up
What are recessional moraines?
Where glacier retreats in summer and moves slightly forward in winter leading to multiple lines of ridges, multiple terminal moraines
What are drumlins?
- small egg shaped hills found on floor of glacial trough
- steep side is the stoss, shallow side is the lee
- elongated features that can reach up to 1km in length and over 500m in width, up to 50m on height
- a cluster of drumlins is a swarm
How are drumlins formed?
- when glacier melts, a moraine is formed around an obstacle, as material builds up around it
- steep edge faces upstream and shallow edge goes downstream where ice flows over it
Economic opportunities in glaciated regions of the UK?
- tourism
- grazing in uplands
- crops in fertile trough
- forestry
- quarrying
What is a conflict matrix?
Used to identify where strongest conflicts between different groups occur
