Glaciers And Glaciations

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Glaciers And Glaciations

Glaciers are made up of fallen snow that, after long time, is compressed into large, thick ice masses.

Glaciers form when snow remains in one location long enough to transform into ice. What makes glaciers is their ability to move. Because of their mass, glaciers flow like very slow rivers.

Glaciers occupy more less the 10% of the world's total land area, and most of them are located in Polar Regions like Antarctica and Greenland.

Glaciers are residues of the Ice Age, when ice nearly covered the 32% of the land, and 30% of the oceans.

An Ice Age can occur if cool temperatures are constants for long periods of time, allowing polar ice to advance into lower latitudes. Within the past 750,000 years, scientists realized that there have been at least eight Ice Age cycles, separated by warm periods (interglacial periods). Currently, the Earth is reaching the end of an interglacial period, so this means that in a few thousand years there will be another ice age. This is part of the normal climate variation cycle.

As said before, glaciers begin to form when snow remains in the same area for long periods of time, where enough snow accumulates to transform into ice. Each year, new layers of snow cover and compress the previous layers. This compression makes the snow to re-crystallize. Slowly, the grains grow larger and the air pockets between the grains get smaller, causing the snow to slowly compact and increase density.

After two winters, the snow turns into "firn" (firn is the middle state between snow and glacier ice). At this point, snow is half dense than water.
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Glaciers live a dynamic existence. Many elements help the glacier to form and growth. When snow falls in the accumulation area, it adds to the glacier some mass. As the snow slowly turns to ice, the glacier increases in weight, forcing glacial movement. Down the glacier there is the ablation area, where most of the melting and evaporation occur. Between these two areas a balance is reached, so here the glacier is in equilibrium. If the equilibrium is disturbed, either by increased snowfall or even by excessive melting, the glacier moves at until he reaches its normal position.
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