There are two basic types of glacie

There are two basic types of glaciers, those that flow outward in all directions with little regard for underlying terrain
and those that are confirmed by terrain to a particular path. The first category of glaciers includes those massive
blankets that cover whole continents, appropriately called ice sheets. There must be over 53,000 square kilometers of
land covered with ice for the glaciers to qualify as an ice sheet. When portions of an ice sheet spread out over the
ocean, they form ice shelves. About 20.000 years ago the Cordilleran Ice Sheet covered nearly all the mountains in
the southern Alaska, western Canada, and the western United States. It was about 3 kilometers deep in its thickest
point in northern Alberta. Now there only two sheets left on Earth, those covering Greenland and Antarctica. Any
The second category of glaciers includes those of a variety of shapes and sizes generally
called mountain or alpine glaciers. Mountain glaciers are typically identified by the landform that controls their flow.
One form of mountain glaciers that resembles an ice cap in that it flows outward in several directions is called an ice field. The difference between an ice field and an ice cap is subtle. Essentially, the flow of an ice field is somewhat controlled by surrounding terrain and thus does not have the domelike shape of a cap. There are several ice fields in the Wrangell, St.Elias, and Chugach mountains of Alaska and northern British Columbia. Less spectacular than large
ice fields are the most common types of mountains glaciers: the cirque and valley glaciers. Cirque glaciers are found
in depressions in the surface of the land and have a characteristic circular shape. The ice of valley glaciers, bound by
terrain, flows down valleys, curves around their corners, and falls over cliffs.