What do you know?
What is a glacier?
A glacier is a slowly moving mass of ice.
Key points
- Glaciers are large masses of frozen ice that move slowly downhill.
- As glaciers move, they wear away the surrounding land through erosion.
- Glaciers sometimes transport material over long distances before eventually depositing it.
What is a glacier?
Glaciers are large bodies of ice that cover about 10% of the Earth鈥檚 surface in cold regions such as Antarctica and the Arctic as well as in high mountain ranges such as The Alps, Andes and Himalayas.
91% of all glaciers are found in Antarctica, 8% in Greenland with the remainder being found across every continent except Australia.
There aren鈥檛 any glaciers in the UK anymore but in the last ice ageLong-term period of glaciation when Earth occasionally experiences a reduction in its surface and atmospheric temperatures., 20,000 years ago, they covered much of the country and are responsible for much of the landscapeThe visible areas of land. we see today.
Glaciers are made up of snow that has built up over many years. The weight of the layers of snow become compressed into ice. This process, for most glaciers, takes over a hundred years.
Due to their size and gravityGravity is a force that pulls all things toward one another. We commonly experience gravity by being pulled downwards by the Earth., glaciers flow like very slow rivers.
As a glacier flows, weatheringThe process of breaking down of rocks and weakening rocks. takes place on the land around it.
The main weathering processAn action or sequence of actions that shape or change the environment. is known as freeze-thaw weathering. This is where water, either rain water or meltwater from the glacier, seeps into cracks in rocks and freezes solid as temperatures drop. As this water freezes it expands. If this process happens repeatedly it will weaken the rock.
Question
Are there any glaciers in the UK?
There are no glaciers in the UK today but during the last ice age they covered much of the country.
Test your knowledge
Glacial processes
As glaciers move a number of processes take place. These are erosion, transportation and deposition.
Erosion
Although glaciers move very slow, they are very powerful. As they move, they erosionWhere rocks are worn away, in this case by the movement of the glacier. the land around them in two ways.
Plucking 鈥 sometimes rocks get frozen to the base, sides and back wall of the glacier. The movement of the glacier pulls these frozen rocks away.
Abrasion 鈥 rocks trapped in the glacier rub against the valley floor wearing it away like sandpaper.
Transportation
Eroded material, such as rock, is moved by the glacier. This material is known as moraine. Some is frozen inside the glacier; some is carried on the top of it and some is pushed in front. This is called transportation.
Deposition
As ice starts to melt, this moraine is dropped off and this is now known as till or boulder clay. This process is called deposition. Glaciers are capable of transporting even heavy boulderA rock fragment with a size greater than 256 millimetres (25.6 centimetres or 10.1 inches) in diameter.. When these are deposited they are known as erratics.
Question
What is the name of the process where rocks trapped in the glacier rub against the valley floor wearing it away like sandpaper?
The process is called abrasion. It occurs when rocks and stones become embedded in the base of a glacier and are rubbed against the valley floor as the glacier moves.
Test your knowledge
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Make decisions for the planet in this KS3 geography game.
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