The river of ice is called a glacier. The term glacier is a French word where glace means ice. There are two groups into which glacier falls:
(a) Alpine glacier
(b) Ice sheets
Alpine glaciers are formed on the mountainsides and they usually move downwards through the valleys. There are times when alpine glacier also deepen the valleys by pushing away the dirt, soil, and other materials. These glaciers are found in high mountains.
Ice sheets form broad domes and usually spread out in all the directions. When the ice sheets spread, they cover all the areas such as valleys, plains, and mountains with thick blanket of ice. The continental glaciers are the largest ice sheets and are covers most of the Antarctica and islands of Greenland.