Glaciation Flashcards
Defention of a cold environment
Areas of land permanently covered by ice. They are covered by glaciers ice sheets and frozen soil or rocks. The temperature is constantly below freezing
Why do areas get colder with a higher altitude?
There is often less ground to heat the air and less air particles to vibrate (10.0m = -1c)
What is continentality and how does it effect a climate?
How far a place is from the ocean (comparing marine and continental climates). This effects a places climate as the sea heats up and cools down slowly so if a places continentality is near the sea it will never get too warm or cold quickly as it is regulated by the sea but if a place is land locked it will have more extreme weather (this is called a continental climate)
What is the accumulation and ablation zone?
The accumulation is when there are inputs to the glacial budget and the ablation zone is where there are outputs to the glacial budget
What things cause glacial accumulation?
- Rocks from the mountain
- snow fall
- avalanches
Accumulation > ablation = ?
Advance in winter
Ablation > accumulation = ?
Glaciers retreat in summer
Where is the most powerful part of a glacier as it flows?
The middle as there is less friction
Name the three types of glacier erosion and what they do…
Freeze thaw weathering: 1. rain collects in cracks 2. The water freezes and expands making the crack bigger 3. Over time the rock breaks off causing scree and rocks for abrasion and glacial accumulation
Abrasion: rocks and scree from the mountain have a sand paper effect as they rub against the floor
Plucking: melted water from beneath the glacier refreezes and any weakly attached rocks are plucked away leaving jagged rocks which are smoothed by abrasion
What are some common corrie landforms?
Steep back wall, armchair shape, rock lip, scree, moraine, lake and in some cases a waterfall.
Describe the formation of a corrie
- Snow builds up in a small hollow in the side of a mountain and year later a glacier forms through the pressure of the snow
- The glacier moves under its own weight in rotational movement
- A small corrie filled with ice flows onto the main valley
- The mountain top (steep back wall) is eroded by freeze thaw weathering which breaks off into the glacier
- Erosion on the back wall is caused by plucking. The back wall has a vertical jagged appearance
- Rocks that have fallen into the ice scrape the floor forming a hollow shape from abrasion and rotational movement.
- There is less erosion at the front of the ice because it is thinner. This is where a moraine forms
- When the ice melts a deep lake called a tarn forms and the moraine becomes a rock lip
Now check out the echalk animation https://www.echalk.co.uk/Geography/ice/corrieFormation/corrieFormation.html
When is a “v” shaped valley carved out?
A “v” shaped valley is carved out by a river
When is a “u” shaped valley formed?
(Sometimes glaciers follow the path of a river) A “u” shaped valley is formed by a glacier as the floor and walls of a valley are eroded wider and deeper
Formation of an Arête
- 2 hollow filled with snow form back to back on a mountain
- Like glacier they erode the ground with abrasion from rocks that were acquired by freeze thaw weathering
- As the glaciers form back to back the back wall is steepened on each side until the top of the mountain is at a knife like point and when the ice melts the two corries are formed
Formation of a pyramidal peak…
1) snow gathers in 3 hollows back to back. It compresses turning into firm ice
2) the glaciers abrade 3 deep hollows using materials that have been plucked
3) when the glaciers melt and corries form the steep backs of all three corries due to freeze thaw weathering and this forms pyramid shape with aretes on each meting point of the corries. The sharp peak is kept by freeze thaw weathering.
