A thick, long-lasting mass of ice accumulated on land surfaces. Can last hundreds or thousands of years. B. Glaciers flow.
Ice moves out from a zone of accumulation under the force of gravity.
Because the ice is so thick, the base is not restricted to flowing downhill. It can engulf terrain features beneath it, and its base can be pushed upslope. With rare exceptions, glaciers move exceedingly slowly. Rate of flow ranges from about an inch to a foot a day. A. Snowfall must exceed snowmelt, year after year.