Glaciers Flashcards
What is a glacier?
A buildup of many compressed layers of ice and snow. It moves down slope due to the influence of its own weight and gravity.
What is the interglacial period?
Period between glaciations.
The last glaciation was 13,000 years ago
Explain the formation of a glacier
Fresh snowfall and accumulates on the ground
As more snowfalls layer beneath it are compacted. Due to the pressure the snow melt slightly before re-freezing again around a smaller grains of ice called firn
Further compression makes a solid block of glacial ice
What is blue eyes?
Compaction has removed all oxygen from it
What are the two ways glaciers move?
Basal sliding
Plastic flow
Explain basal sliding
Occurs when there is a thin layer of water at the base of the glacier. Water axis lubricant and allows the glacierto slide down slope. Most basal sliding takes place on steep slopes and mainly occurs during summer months.
Explain plastic flow,
It is very cold the climates where bottom layers of glacier are too cold to melt so basal sliding cannot occur. The weight of the overlying ice pushes down creating horizontal layers that can bend and slow. It doesn’t occur Iglesias less than 50 m thick as there is not enough pressure.
What are the two types of glacial erosion?
Plucking
Abrasion
Describe the process of glacier plucking
It occurs when pressure melts water at the base and sides of the glacier. Daughter sees into cracks joints of rock then freezes and expands by 9%. As the glacier is now frozen around the weekend rock it pluck the rock out as it goes down.
Explain abrasion
Large pieces of jagged rock are frozen into the base inside of the glacier as moved down slope these pieces scrape across the valley sides causing deep scratches in the bedrock which further aid plucking
What factors affect the rate of erosion?
Glacier thickness, the greater the depth of ice the greater the rate of erosion
Gradient, glaciers move faster on steep slopes
Resistance of rock, soft rock is eroded quicker
What is moraine
Material transported by glaciers
What is super glacier material in terms of glacial transportation?
Super glacial material is carried along the top of the glacier
What is an englacial material in terms of transport?
Material carried within the glacier. May need you to whether the material falling through crevices.
What is subglacial material in terms of glacial transportation?
Carried along the ground beneath Iglesia. Accumulates from material that was plugged from the valley floor.
What is the zone of ablation?
It is where melting occurs at the endpoint of the glacier usually in lowland areas
What is glacier drift?
Deposited material
What is bolder clay
Material deposited directly from glacier. It is unsorted unstratified and unconsolidated so is easily eroded.
What is fluvio glacial deposition?
Involves melt water from glacier spreading outwards in front of glacier carrying sand and gravel. Material sorted according to size and stratified.
Describe the glacier erosion feature of a cirque
Hollow in mountain with three steep size. The birth place of a glacier.
Describe the feature of erosion the tarn
Meltwater leak left behind in a cirque
Describe the feature of erosion an arête
Narrow knifelike Ridge that separates two cirques
Describe the feature of erosion a pyramidal peak
Isolated mountainous peak that forms when three cirques form back to back
Describe the feature of erosion a u shaped valley
Steep sided Valley with a flat wide floor
