Dr. John Clague
Department of Earth Sciences Simon Fraser University
Types of Glaciers
You can have small glaciers; typical glaciers that you might see in Banff National Park or Jasper National Park, they are called alpine glaciers. Sometimes if they are confined to a little bowl in a high mountain they might be called cirque glaciers, but they tend to be small bodies of ice.
At the other end of the scale you can have these huge ice sheets that can cover continental size areas. Currently we have two of these on earth, one in Greenland called the Greenland Ice Sheet and the other in Antarctica called the Antarctic Ice sheet (not surprisingly!) But the Antarctic Ice Sheet is actually a composite of two separate ice sheets, an eastern ice sheet and a western ice sheet. And there is a huge amount of water locked up in these ice sheets. If you were to melt all that ice and return the water to the oceans, you would raise sea levels probably 50, 60 or 70 meters all around the earth. It’s a huge amount of water – it’s the largest reservoir of water on earth, but it occurs in this frozen form.
In contrast, valley glaciers, or alpine glaciers are much, much smaller. They don’t hold anywhere near globally the amount of water that we have in ice sheets. Valley glaciers typically form in high mountain areas around the world. In Canada, they occur in western Canada in the Coast Mountains and in the Rocky Mountains and in a number of other mountain ranges throughout the region. There are very few in the United States because you are getting a little closer to the equator and it is harder to maintain glaciers under those more temperate conditions, but there are some. Even in equatorial areas, if you get high enough, you can still get glaciers. So there are glaciers on Mount Kilimanjaro, it’s a mountain that is some 6000 meters high, so there are small glaciers there. The ice sheets are a different matter. They can occur in lower areas. They are situated close to areas where you either have extreme cold, as in Antarctica, or where you have an abundant source of moisture, as in the North Atlantic.