Glaciers Flashcards
(22 cards)
Accumilation zone
More snow is added each winter to the glaciers by avalanches or snow and turns to ice
Ablation zone
Every spring and summer the surface of the glacier melts, and ice is lost through evaporation.
Advance
If there is more accumulation than ablation the glacier melts and moves down the valley
Retreat
If ablation is greater then accumulation, than the glacier’s snout melts and moves backwards.
Why does snow effect movement of the glacier?
As snow becomes more compacted the powder snow turns dense and becomes blue ice.
Wgat is a cold enviroment
Areas of land that are permanently of mostly covered in ice sheets and Glaziers. The temperature is below freezing
Abrasion
Abrasion is moving down loose sediment and as the rocks scrap the bed and walls when traveling with the glacier, it erodes them.
Plucking
Meltwater gets into crack in rocks and freezes, making the ice attach to the rock but the expands until the rock breaks loose
Freeze thaw weathering
This is when rain water collects in the cracks and when the temperature goes below 0°c the water freezes and expands until the pressure becomes to much and the rocks pluck of.
How a corrie is made
The snow builds up in a hollow on the north face of mountain sides. A small corrie full with ice, flows out onto the main valley glacier.
The ice moves under its own weight in a circular way called rotational movement. The mountain top is weathered by freeze-thaw until it breaks sediment off which falls into the ice. The back wall erodes by plucking to create a jagged shape as well as abrasion on the floor. As the ice is thinner at the front of the corrie there is less erosion so a lips or moraine is formed. When the ice melts a tarn is formed.
How is an arête formed
Two corries on the different sides of a mountain are formed which erodes the mountain to becoming an arête
How is a pyramidal peak formed
Three or more corries on the different sides of a mountain are formed which erodes the mountain to becoming an arête called a pyramidal peak
What is a hanging valley
A small valley are normally coursed be a corrie and allows a path of a small stream to flow down to the main valley.
What is a misfit stream
A river that was formed by the melting of a glaciers in a valley that did not cause any of the erosion.
What is a glacial budget
The glacial budget refers to the balance between the amount of inputs versus outputs affecting the glacial system.
What is a ribbon lake
A ribbon lake is a long and narrow, finger-shaped lake, usually found in a glacial trough.
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 things cause glacial accumulation?
- Rocks from the mountain
- snow fall
- avalanches
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
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
