Quiz: Remember the definition of mal de mer?
1744, from French glacier, from Savoy dialect glacière "moving mass of ice," from Old French glace "ice," from Vulgar Latin glacia (cf. Old Provençal glassa, Italian ghiaccia), from Latin glacies (see glacial).
A large mass of ice moving very slowly through a valley or spreading outward from a center. Glaciers form over many years from packed snow in areas where snow accumulates faster than it melts. A glacier is always moving, but when its forward edge melts faster than the ice behind it advances, the glacier as a whole shrinks backward.
A large mass of ice formed over many years that does not melt during the summer. Glaciers move slowly over an area of land such as a mountain valley.
Note: Glaciers exist in high mountains throughout the temperate zones and cover most of Antarctica. Glaciers recede during warm periods and can expand during cold periods, creating ice ages.
Note: A significant percentage of the water of the Earth is locked up in glaciers.