Ice comes in many forms and can be categorized by its size, shape and behavior. Glaciers fall into two main groups: mountain glaciers and ice sheets.
also known as alpine glaciers, form in high mountain regions and move downward through valleys. These glaciers can range from small masses of ice to a long system filling an entire mountain valley.
unlike mountain glaciers, are not limited to mountainous areas. They spread out from their centers in all directions. Also called continental glaciers, ice sheets are glacial bodies that are larger than 19,305 square miles. As they spread, they cover the land surrounding them with a thick blanket of ice. Ice sheets cover most of Antarctica and Greenland. The Antarctic ice sheet is the largest single mass of ice on Earth and over 3 miles thick in some areas.