Cutting Edge Technology

Here are two videos showing some of the features created by glacial erosion and deposition:

Cirque du Striae

Aside from the aforementioned features of glacial deposition, there are also features created by glacial erosion. Indeed, ice can erode in two ways; by plucking and abrasion.

Plucking occurs when a glacier stops moving, meaning that any meltwater at the base of the glacier refreezes, sticking onto the rock. Once the glacier begins to move again, it plucks pieces of this rock away with it, eventually transporting it to another area to be deposited.

Abrasion occurs when previously plucked rocks carried by the glacier scrape the surface of the rock they are travelling across. This wears away the surface of the rock, creating scratches known as 'striae'.

Features formed by glacial erosion:

1) Cirque: A cirque is a large hollow surrounded by 3 steep sides, which may also contain a lake (in which case it is known as a 'tarn'). It was formed when ice in mountain hollows plucked rocks and deepened the hollow itself. Eventually, the ice built up,overflowed and began to move downhill as a glacier. Here it melted and remained as lakewater in the hollow created.

2) Arete: An arete is a narrow, steep-sided ridge which occurs when two cirques form back-to-back or beside each other. Sometimes, three will form around a peak, leaving just one steep side called a 'pyramidal peak'.

3) Glaciated Valley: This is a former valley which was widened, and straightened when a glacier went through it.

4) Ribbon Lake: Ribbon lakes are scooped out of the floor of a glaciated valley, usually in areas of softer rock. These hollows later filled with meltwater, and are also called paternoster lakes if they are linked together by a stream.

5) Hanging Valley: A hanging valley is a small glaciated valley high above the main one. This was formed by a much smaller glacier with less power to erode than the other, meaning when it melted, the valley was left almost 'hanging' above the main valley.

6) Fjords: A fjord is a narrow, deep inlet which were once glaciated valleys but were flooded when the sea level rose due to excess meltwater.

Glaci-Nation?

Defined by the Oxford English dictionary as "a period of long-term reduction in the temperature of the Earth's surface and atmosphere", an ice-age is essentially a time during which glaciers cover the ground. It is the period following this ice-age, however, as the temperature begins to rise and the cold weather declines, that these glaciers begin to melt, forming many different and interesting features.

The features formed by glaciers are usually divided into two groups; those formed by glacial erosion and those by glacial deposition.

Features formed by glacial deposition:

1) Drumlin: A drumlin is an oval-shaped hill made of boulder clay, which occur in groups known as 'swarms'. They were formed when boulder clay was deposited by moving glaciers and smoothed into shape as the glacier moved on.

2) Moraine: A moraine is a mound or ridge made of rock, stone, sand and clay that was transported and then deposited by a glacier. Moraines are made of material deposited by a glacier, such as gravel, clay, or sand. There are 4 main types of moraine:

a) Terminal Moraine (at the end of the glacier)

b) Lateral Moraine (at the sides of the glacier)

c) Medial Moraine (in the middle where two glaciers meet)

d) Ground Moraine (covers the valley floor)

3) Erratic: An erratic is a large rock that was picked up by a moving glacier and deposited in another area of a diferent rock type.

4) Boulder Clay Plain: A boulder clay plain is usually a lowland area covered by a mixture of boulders, clay, sand and rocks, all deposited by a melting glacier whose strength and energy was diminishing.

5) Esker: An esker is a narrow ridge made of sand, formed when meltwater streams flowing through the ice became blocked with deposits of rock, clay and sand. These deposits were then left behind after the glacier has melted away.

6) Outwash Plain: Outwash plains are flat areas of snad and gravel, which can be found in front of terminal moraines. They were formed when meltwater spread out from the glacier, carring bits of sand rock and gravel. After a while, however, the flow of water began to lose its energy and so deposited its load.