Ice Sheets

Maximum extent of the North American ice sheets during the Last Glacial Maximum, 20,000 years ago
A reconstruction of the maximum extent of the Laurentide and Cordilleran Ice Sheets, which covered much of North America approximately 20,000 years ago

Courtesy of NOAA Science on a Sphere

Ice sheets are large, continental-scale (greater than 50,000 sq. km or 19,305 sq. mi in area) ice masses that accumulate in extensive, high elevation catchment areas. They are drained by smaller outlet glaciers or ice streams that flow out from them in different directions.

Today, the only ice sheets on Earth are the massive ice bodies in Antarctica and Greenland. However, during the last ice age (approximately 20,000 years ago), two ice sheets covered much of northern North America. These ice sheets shaped much of the landscape there, including a few of our parks.

Find Your Park: Which Parks Have Been Affected By Ice Sheets?

To learn more about glaciers, glacier features, and glacial landforms, see the Glaciers & Glacial Landforms Page.

Part of a series of articles titled Types of Glaciers.

Last updated: November 19, 2018