Glaciation Flashcards
What is a glacier?
A glacier is an enormous slab of ice that formed over time in a very cold area.
What are the two main types of glaciers?
1. Alpine glaciers form high up in mountain ranges and move slowly downhill under their own weight.
2. Ice sheets are a type of glacier that covers a very large area; often referred to as continental glaciers.
What is an ice age?
An ice age is a long period of global cold temperatures that results in the expansion of glaciers.
What is the term often referred to as the times between ice ages called?
The times between these ice ages are called interglacial periods.
What is meant by the zone of accumulation?
The upland area where snow builds is called the zone of accumulation.
What is meant by the glacier’s sole?
The bottom section of a glacier that is in contact with land is called the glacier’s sole.
Explain the process plucking.
Plucking is when rocks, trees and other materials become frozen inside the glacier and are ‘plucked’ from their original position as the glacier moves slowly downhill. As the glacier moves, friction between ice and rock at the sole creates heat, which melts some of the ice. This water seeps into cracks in the rock. The water then re-freezes around the rock, allowing the moving glacier to transport it.
Explain the process of abrasion.
As the glacier moves, the rocks attached to it scratch and scrape the surface rock underneath and on the sides of the valley. The scratch marks left behind on rocks are called striations.
Explain the formation of a U-Shaped Valley.
• When a glacier moves out of a cirque and down the mountain, it follows the easiest route possible.
• This route is often a V-shaped valley that has previously been carved out by a river.
• The glacier uses plucking and abrasion to widen and deepen the valley. This changes it from a V-shaped valley to a U-shaped valley.
• As the glacier moves through the valley, it also cuts off the tips off the interlocking spurs created by the river, leaving behind truncated spurs.
E.g. Glendalough
What causes an ice age?
- Earth’s orbit and axis
- Earth’s atmosphere
- Ocean currents
Explain how material is transported by glaciers.
As glaciers move, they gather material through plucking and abrasion. They also gain material as scree falls from higher slopes and lands on the glacier. All of this transported material is called the glacier’s load.
Explain in your words what a morraine is?
A moraine is made from glacial till such as weathered stone, rock and soil, deposited by a glacier as it moves through a valley.
Explain how boulder clay is made.
As the glacier melts, it deposits its load of eroded material consisting of boulders, clay, sand and stones. Boulder clay is very fertile and excellent for agriculture.
What is boulder clay?
A boulder clay plain is a lowland area that is covered in a layer of boulders, clay, sand and stones called boulder clay.
Explain the formation of any landforms of glacial deposition (Eskers)
• When a glacier begins to melt, streams of meltwater carrying a load of eroded material flow through a tunnel that is carved out under the glacier.
• When the load becomes too great, some material is deposited on the bed of the meltwater stream.
• The stream loses its energy when it exits the tunnel and it deposits the remainder of its load. This forms a ridge of sand and gravel on the surrounding plain.
• This ridge is known as an esker. Roads have been built on eskers in many areas as they provide good foundations.
