Geo - Glaciation Flashcards
How do glaciers form
Snow which never melts, layers up compressing to form ice and starts to slip downhill where it’ll eventually melt
What’s the snowline
The line where ice doesn’t ever melt
What is the birthplace of glaciers
Corries
What is basal slippage
Where meltwater Underneath the glacier lubricates it allowing it to slip downhill
What’s a cravace
A crack in glacial ice
What’s a glacial surge
Where large amounts of ice move hundreds of meters
What’s moraine
Material being carried by the glacier which has fallen from the valley sides
What is abrasion in a glacier
The sandpapering effect where rocks being carried by the glacier grind away at the valley sides eroding them away
What is plucking
Where rocks are ‘plucked’ as meltwater freezes and bonds them to the moving glacier
Where is moraine deposited
At the snout of the glacier where the ice melts
What is glacial till/Boulder clay
The rocks left behind as the glacier retreats
What is a drumlin
Large hills of glacial till caused by rapid retreat
How can glacial till be sorted
Through meltwater rivers which carry the sediment
What is internal deformation
Where ice crystals slowly deform aligning and allowing the glacier to move - very slowly - only in very cold conditions where there is no meltwater
Define a Corrie
Large hollowed out depressions found on the upper slopes of glaciated valleys
How does a Corrie form
- Snow gathers in slight depressions in the rock compressing into ice over many years
- Glacial ice builds up and deepens the depression though plucking and abrasion as the glacier moves through rotational slip
- After the glacial period the Corrie fills with meltwater becoming a tarn (Corrie lake) with a rock lip due to the deposition of moraine
What is an arête
Where two corries meet forming a knife-edge ridge
What is a pyramidal peak
Where three or more corries form a single peak
How is a U-shaped valley formed
As a glacier moves through a V-shaped valley it erodes away deepening and widening it forming a flat bottomed valley
What are truncated Spurs
Where interlocking Spurs are destroyed as a glacier cannot move around them forming a singular straight valley
What are ribbon lakes
Deep and long lakes at the base of a U-shaped valley
How are ribbon lakes formed
A higher rate of erosion in a glacier either from
1. the glacier meeting a softer rock (geology) or
2. The meeting of a tributary glacier which would increase the ice mass and therefore increase the rate of erosion
After the glacial period these hollows fill with meltwater becoming ribbon lakes
What is a hanging valley
Where a tributary glacier cannot erode to the same level as the main glacier, often marked with a waterfall
What is lateral moraine
Rocks which have fallen from the valley sides onto the glacier, building up on the sides
