Describe the extent of the ice covering the UK during the last Ice age
- all of Scotland
- the North of England
- most of Wales
- all of Northern Ireland
How long ago was the last ice age?
About 20,000 years ago
What is a glacier?
A mass of ice that covers the land
Why are glaciers important in explaining the UK's physical landscapes?
As glaciers move, they erode the landscape, creating many of the UK's physical landscapes.
What causes a glacier to move?
The weight of the ice and gravity pulling it down hill.
What is the main weathering process in a cold environment?
What is freeze-thaw weathering?
When water gets into the cracks in a rock, it freezes, expanding to form ice. This puts pressure on the rock. As the ice thaws, it reduces in size, releasing the pressure. This repeating process causes the rock to break apart.
When glaciers move downhill, which two erosional processes happen?
What is meant by 'plucking'?
When meltwater on the bototm or sides of a glacier refreeze to surrounding rock. As the glacier moves, loose fragments of rock are pulled ('plucked') from the surface, leaving behind a jagged surface.
What is 'abrasion'?
Debris picked up by the glacier then scours (scrapes and scratches) the valley floor as the glacier moves over the landscape. It acts like 'sandpaper'.
What is 'rotational slip'?
The curved movement of a glacier across a hollow in the landscape.
What is 'bulldozing'?
As a glacier moves, it pushes debris forward.
What is 'moraine'?
The accumulation of till that is deposited by the glacier
What is 'till'?
Broken rock fragments left behind by a glacier. It is comprised of angular material of different sizes (unsorted).
When does deposition occur?
When ice melts
What is 'outwash'?
The finer pieces of sediment that have been broken down and rounded by attrition, that have been washed away by meltwater and deposited.
Name the 7 landforms created by glacial erosion
- Pyramidal peak
- Truncated spurs
- Hanging valleys
- Glacial troughs
- Ribbon lakes
What is an arête?
A narrow, steep sided ridge formed between two corries
What is a pyramidal peak?
A pointed peak of a mountain caused when three corries have formed on a mountainside.
What is a corrie?
Large hollowed out depressions located on the hillsides.
What are the characteristics of a corrie?
- Steep back wall
- Raised 'lip' at the front
- Sometimes contain a tarn (lake)
What process causes a corrie?
Erosion. As the ice moves by rotational slip, it erodes the hollow shape into the hillside.
What is a 'tarn'?
A lake left behind when glacial ice melts in a corrie.
What is a 'ribbon lake'?
When a glacier moves, it erodes the landscape, leaving hollows in the ground. Meltwater sits in these long, thin hollows leaving behind a 'ribbon lake'.
What is a 'truncated spur'?
Ice is unable to flow around interlocking spurs that may have formed within the valley. As a result, the glacier cuts straight through leaving behind cliff like edges on the valley sides.
What is a 'glacial trough'?
Steep sided valleys with flat bottoms. They are created when glaciers form in a valley, often turning a V-shaped valley into a U shaped trough.
What is a 'hanging valley'?
A smaller tributary valley located above the main glacial trough. They are formed by smaller glaciers that do not have the same erosive power as a glacier.
How is a corrie formed?
- Snow accumulates in a small depression on a valley side
- Freeze thaw weathering causes the hollow to deepen
- More snow can accumulate in the deeper hollow
- Over time it compacts and freezes, creating a glacier
- Through rotational slip, the glacier moves forward, scooping out (abrades) the hollow
- The thinner, front of the glacier is unable to erode, thus deposits material, forming a lip.
How is an arête formed?
When two corries form on a hill side, narrowing the land between them both, leaving behind a knife-edged ride (arête)
How is a pyramidal peak formed?
When three corries form on a hillside, narrowing the land between them both, leaving behind three knife-edged rides (arête) which result in a pointed peak (pyramidal peak)