What do you known about the working of glacier.

WORKING OF GLACIER

The glacier is a stream of ice and snow that moves in its valley under the influence of gravity. A glacier is a huge mass of ice that moves slowly over land. The term "GLACIER" comes from the French word glacé (glad-say), which means ice. Glaciers are often called "Rivers of Ice." 

FORMATION OF GLACIER :

When snowfall occurs, the lower snowflakes compress by the weight of over-lying snowflakes of subsequent falls and gradually develop into a more compact, dense form called firn or Neve. 

Firn is compacted snow which has experienced one winter's freezing and survived a summer's melting. Air is progressively squeezed out, and after 20-40 years, the Firn will have turned into solid ice. Once the ice has formed, it may begin to flow downhill under the force of gravity. 

TYPES OF GLACIER :

The shape of the glacier is molded by the type of surface on which the glacier flows. According to their shape and size following four types of glaciers are generally recognized.

  1. VALLEY/ALPINE GLACIER :

It occupies a mountain slope and moves downward under the pressure of snow, slope, and gravity. It may be single or have tributaries, which join the mainstream of glaciers. For example, Baltoro, Biafo Glacier is located in Pakistan. 

2. PIEDMONT GLACIER :

It is formed at the foothills of mountains. When the glaciers extend onto the lowland areas, they spread out and merge. For example, Malaspina Glacier in Alaska. 

3. CONTINENTAL GLACIERS / ICE SHEETS / ICE CAPS:

Glaciers covering vast areas of a continent are known as continental glaciers. The snow that falls from year to year goes on these regions are covered by an extensive ice mass, a gigantic ice dome that hides beneath it all the surface irregularities irrespective of their heights or depths. For example, Antarctica and Greenland ice sheets. Small Ice sheets are known as ice caps, normally found in the summit areas of high mountains. 

WORKING OF GLACIER :

Glaciers' work is more prominent in cold areas, covered by snow and ice for most of the year. Although glaciers' area of activity is limited, it is more important because it can carry big boulders along with ice like a river; a glacier also performs three-fold work of corrosion, transportation, and deposition. 

EROSIONAL WORK OF GLACIER :

In this process, the material (sediments) rub against the valley sides and floor. It usually produces smoothened, gently sloping landforms. This involves the pulling away of masses of rocks during ice movement. 

LANDFORMS PRODUCED BY GLACIER EROSION:

A cirque is a larger circular or amphitheater-like or an armchair-type of hollow cut into the mountain ridge. When the glacier moves in its valley, its sediments pull the rocks from the surface, creating depressions of various sizes called a cirque. 

When the ice melts in cirques, the cirques are filled with water taking a Lake called Tarn lakes. For example, Great Lakes in North America. 

When the glacier moves in its valley, due to the friction of sediments( carried by the glacier) against the land surface (Abrasion), different scratches are formed on the land surface called striations. For example, It is founding central Park, Newyork, USA. 

When the wall between two adjacent cirques is eroded, it takes the form of col. It becomes an easy way for travelers. An "arete" is a narrow ridge of rock that separates two valleys. It is typically formed when two glaciers erode parallel U-shaped valleys. Aretes can also form when two glacial cirques erode towards one another. The glaciers turn its valley into a U-shaped valley with steep valley sides and a flat floor with its abrasion action. For example, ST. LAWRENCE VALLEY, USA. 

The tributary glaciers from a hanging valley. It is higher than in the main valley. 

When a rock comes in a glacier way, it sides over the rock; it forms smooth sides due to abrasion action. When the glacier Valley appears to be drowned by the sea, but actually they are deep secured glacial troughs, known as fiords. Ice in some fiords may have accumulated to more than 1000 meters below current sea-level. 

TRANSPORTATION OF GLACIER:

The glacier is capable of carrying large quantities of boulders and sediments, known as moraine. 

The debris may be derived from rockfalls on the valley sides. It can be transported on the surface of the glacier(supraglacial debris). It can be buried within the ice(Englacial). It may be at the base of the glacier (subglacial). 

GLACIER DEPOSITION :

When a glacier becomes over-saturated with sediments or when it melts, it starts deposition and produces depositional landforms. 

Erratics are the boulders picked up and carried by ice, often for many kilometers and later deposited in completely different lithology areas. It is found IN the USA. 

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Jul 28, 2020, 12:33 PM - Divyansh ?
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