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Glacier

The Baltoro Glacier in the Karakoram Mountains. 62 kilometres (39 mi) in length, one of the longest alpine-type glaciers

A glacier is a large body of ice and snow. It forms because the snow in an area does not all melt in summer. Each winter, more snow is added. The weight of all the snow creates pressure. This pressure turns the lower parts of the snow into ice. After this happens for many years, the glacier will start growing large. It becomes so heavy that gravity causes the ice to move. It flows downwards like water but very slowly. A glacier only moves about 50 metres (160 ft) per year. New snowfalls replace the parts that flow away.[1][2]

Glaciers are the largest sources of fresh water on Earth. The largest bodies of salt water are the oceans.

Creation

 
Icebergs breaking off glaciers at Cape York, Greenland

Glaciers will only form in places that are cold enough and get enough snow over time. This can take a long time. It often takes tens or hundreds of years for a glacier to form. There are two kinds of glaciers: continental glaciers and alpine glaciers. Alpine glaciers are also called mountain glaciers.

  • Continental glaciers are glaciers that spread out over a large area of land.  They were created mostly during the Ice Ages a long time ago. There are still some continental glaciers in Greenland and Antarctica. They often flow downwards into the sea and break up. The broken parts that float in the sea are called icebergs.
  • Alpine glaciers form in mountain areas. They are smaller than continental glaciers. Alpine glaciers usually flow until they reach a point where the temperature is warm enough that the ice melts completely during the summer.

Effects

Glaciers are very important. They have a large effect on the environment. They do this because they are very large and heavy. When they move, they erode mountains and land. Also, since they froze long ago, snow crystals and air bubbles inside are kept in good condition. These can provide a large amount of information for scientists. Recently glaciers have been melting more than they did in the past. Many scientists think this is happening because global warming is changing the climate.[3]

Appearance

Glaciers are blue in color. This is because water is very good at absorbing light. Only the strongest light, with the most energy, is able to escape. Blue is the color of light that has the most energy. Because of this, blue is the only color of light that can escape without being absorbed. The thicker the glacier is, the more blue it appears.

 
 
The front of Perito Moreno Glacier, Patagonia, Argentina

Glacier Media

  • Glacier of the Geikie Plateau in Greenland.

  • The Taschachferner in the Ötztal Alps in Austria. The mountain to the left is the Wildspitze (3.768 m), second highest in Austria. To the right is an area with open crevasses where the glacier flows over a kind of large cliff. The distance from left to right image border is c. 1.5 km in reality.

  • The Quelccaya Ice Cap in Peru is the second-largest glaciated area in the tropics

  • Webber Glacier on Grant Land is an advancing polar glacier

  • A glacier cave located on the Perito Moreno Glacier in Argentina

  • Black ice glacier near Aconcagua, Argentina

  • Shear or herring-bone crevasses on Emmons Glacier (Mount Rainier); such crevasses often form near the edge of a glacier where interactions with underlying or marginal rock impede flow. In this case, the impediment appears to be some distance from the near margin of the glacier.

  • The overhanging icefront of the advancing Webber Glacier with waterfalls (Borup Fiord area, Northern Ellesmere Island). Debris rich layers have been sheared and folded into the basal cold glacier ice. The glacier front is 6 km broad and up to 40 m high. July 20, 1978,

  • Ice cracks in the Titlis Glacier

  • Forbes bands on the Mer de Glace glacier in France

References

  1. ↑ Hambrey, Michael; Alean, Jürg (2004). Glaciers (2nd ed.). Cambridge University Press. ISBN 0-521-82808-2. OCLC 54371738.
  2. ↑ Benn, Douglas I.; Evans, David J.A. (1999). Glaciers and glaciation. Arnold. ISBN 0470236515. OCLC 38329570.
  3. ↑ * Bennett, M.R.; Glasser N.F. (1996). Glacial geology: ice sheets and landforms. John Wiley & Sons. ISBN 0471963445. OCLC 33359888. 37536152.

Uncited references

  • Walley, Robert (1992). Introduction to physical geography. Wm. C. Brown.

Other websites

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