Glaciation!

An Introduction-

During the Ice Age, many areas across the world were permanently covered by ice, including the UK. But what actually is glaciation?

A glacier is a body of ice that moves through a valley. Glaciers have shaped many landscapes through the processes of erosion, deposition and transportation. Glaciers are still shaping parts of the world today!

In more depth-

10,000 to 20,000 years ago, glaciers and ice sheets covered 32% of the land surface. Today 10% is covered by ice. 22% of the land is underlain by continuous or discontinuous zones of permanently frozen ground. The glacial age is not over, it has only diminished in its overall extent and intensity.

At maximum glaciation few areas of the earth were unaffected by ice activity and action. The last world-wide glaciation occurred during the Pleistocene epoch which comprised some twenty extreme cold periods interspersed by periods of milder weather, interglacials.


The Ice Age-

*During the last Ice Age, 2 million to 10,000 years ago the climate was much colder than it is today.
*In upland areas, snow remained on the ground all year. As more and more snow was added each year, it slowly compresses to form ice.

*In some areas, enormous ice sheets covered the whole landscape. The whole of northern Britain was covered in ice. Glaciers as a result have shaped many parts of Britain.
*In other places, ice only filled the valleys, forming glaciers. These glaciers moved downhill and shaped the landscape.
*Today, ice and snow still permanently cover countries within the Arctic Circle, such as Greenland, Northern Canada and parts of Russia.

In-depth Ice Age Britain-

No area of tge UK escaped the effects of the ice age: the landscape we see today was created by ice advances over the British land mass. Three main advances have been recognised:

*Anglican Advance (420,000-380,000 years ago, left major deposits in East Anglia)
*Woolstonian Advance (170,000-130,000 years ago, largely affected North Britain)
*Devensian Advance (115,000-18,000 years ago, depositional and meltwater features in Shropshire, Cheshire and Yorkshire)

Glaciation Erosion-

Glaciers form in hollows on the colder, sheltered side of a mountain. These hollows are called corries. Snow and ice gathers in the hollow and over time the corrie gets larger through freeze-thaw weathering. Freeze-thaw weathering also loosens pieces of rocks which then fall onto the glacier. This material is called moraine.

Inside the hollow ice begins to move in a circular motion, called rotational slip. Eventually the ice will move out of the corrie and over the lip of the hollow. The glacier movesa down the mountain-side. At the front of the glacier is the snout. A lake, called a tarn, may form in the corrie. The steep knife-edged ridge between the two corries is called an arete.


As a glacier moves it erodes in the landscape in two ways:

*Abrasion occurs when pieces of rock carried by the ice wear away the landscape. As the glacier moves it transports material with it, which helps the glacier erode and shape the landscape. The material can be frozen within the glacier or found underneath it.

*Plucking occurs when meltwater under a glacier freezes on to the rock surface. As the glacier moves forward it pulls away large fragments of rock from the surface.

Glacial Deposition-

As a glacier moves downhill, temperatures rise and the glacier begins to melt. As the glacier melts, it deposits the material it has been carrying. This deposition usually takes place in lowland areas. Glacial deposition can create distinct landscape features in lowland areas.

Moraine is the rock material carried by the glacier. It is later deposited to form mounds of unsorted rocks and rock particles, which are called moraines. There are several different types of moraine. These are classified according to when and where they were deposited by the glacier.

Types of moraine:


Other facts-

*Drumlins are mounds od boulder clay, deposited by glaciers and shaped by the moving ice. The ice moved over the drumlins to form small egg-shaped hills.
*Erratics are rocks transported many miles by a glacier and later found in an area of a different rock type.

Glacial landforms provide an important resource for the tourist industry. Glaciation helped to create distinctive and interesting landscapes like the Lake District. Tourists and day visitors may visit areas such as the Lake District to go walking, hiking, mountain climbing or absailing. Many glaciated landscapes are protected from large-scale urban or industrial development. Many are National Parks in rural areas where the main land use is for primary industry, such as farming or mining.