Glacation Flashcards
What happened 1800 years ago?
Ice covered about 30% of the land in the world
What is a glacier?
It is a large body of ice moving slowly down a slope or over a wide area of land.
What are the three processes by which glaciation affects the landscape?
Erosion
Transportation
Deposition
How does a glacier form?
They from in very cold places. Lots of snow falls but not all of it melts and this means that lots of different layers of snow lie on top of each other
What is an ice sheet?
Masses of ice which cover large areas of a continent are called ice sheets.
What is the glacier system?
It consists of inputs, transfers(flows), stores and outputs in the same way as a river
Where do inputs come from (glacier system)
Avalanches and precipitation
What are then outputs (glacier system)
Meltwater and evaporation
Accumulation =
Ablation =
Accumulation = inputs > outputs Ablation = outputs >inputs
What are the three main processes that operate in the glacier system?
Frost shattering or freeze thaw weathering
Abrasion
Plucking
What is frost shattering?
It describes the action of glacial meltwater on joints, cracks and hollows in rock
What happens when the temperature reaches freezing point?
The water inside the rock freezes, expands and causes the rocks to widen
What is abrasion?
The moraine frozen into the glacier scours the valley sides and base and this is the sandpapering effect
What is plucking?
The water at the bottom of the glacier freezes onto rock on the valley base and as the glacier moves, the rock is pulled away from the valley base.
Name four landforms created by glacial erosion and deposition
Corries
Aretes
Pyramidal peaks
Glacial troughs
What is a Corrie?
Snow collects in a natural hollow on the side of a mountain and it turns to ice over time and the hollow is deepened and widened by a Corrie glacier through the processes of abrasion and plucking.
What is an Arête?
It is a ‘knife edged’ ridge formed between two corries
How is a pyramidal peak formed?
It is formed when three or more corries are formed back to back
What is a u shaped valley?
It is when a glacier moves down a mountain and makes a V shaped valley into a U shaped valley?
What are the landforms created by glacial deposition?
Moraines
Drumlins
Erratics
What is a moraine?
It is a type of landform that is created when a glacier deposits the material that it has been transporting.
What are the types of moraine?
Terminal moraine Lateral moraine Medial moraine Ground moraine Recessional moraine
What are drumlins?
They are smooth mounds of deposited material that reach a kilometre or more in length
What are striations?
They are scratches on material that the glacier is carrying
What are erratics?
They are large boulders that have been carried by the glacier and then deposited in an area of different rock type
What happens to a valley at sea level?
It forms a Fjord
What was the mer de glace
A famous glacier found in the Alps
