An ice sheet also known as a continental glacier, is a mass of glacial ice greater than 50,000 square kilometers (19,000 square miles), and contain about 99% of the freshwater on Earth. As ice sheets extend to the coast and into ocean, they become ice shelves. A mass of glacial ice covering less area than an ice sheet is called an ice cap. A series of connected ice caps is called an ice field. Making up ice fields, ice caps, and eventually ice sheets are individual glaciers.
Today, there are only two ice sheets in the world: the Antarctic ice sheet and the Greenland ice sheet. During the last glacial period, however, much of Earth was covered by ice sheets. At Last Glacial Maximum, the Laurentide Ice Sheet covered much of North America, the Weichselian ice sheet covered Northern Europe and the Patagonian Ice Sheet covered southern South America.
- Ice Sheet National Geographic