A glacier is a thick mass of ice which moves over the ground under the influence of gravity. It originates on land form the compaction and re-crystallization of snow. Glaciers form in places where more snow accumulates each year than that melts away. They are found in high latitudes as in the arctic region, or the high elevation as on the Himalayan Mountains above the snow line. The snowline is the lower limit of accumulating snow. Below the snowline the snow melts in summer. The elevation of the snowline varies considerably.
Type of Glaciers
There are three main kinds
The glaciers which originate near the crests of high mountains and move along the valleys just like rivers are called valley G.
At the end of a hilly region a number of valley glaciers may unite to form a comparatively thick sheet of ice. Such as compound G is called Piedmont G.
These are massive accumulation of ice covering extensive areas. Two such glaciers that exist today are the Green land and Antarctic ice sheets. The Greenland ice sheet covers an area of about 1.7 million square kilometers and is over 1500 meters thick.