19.2: What Are the Glacial Types?
What Are the Glacial Types?
Mountain, alpine, or valley glaciers Links to an external site. (Figure 19.2) typically develop in mountainous regions, often flowing out of icefields Links to an external site. that span several peaks or even an entire mountain range. The largest mountain glaciers are found in Arctic Canada, Alaska, the Andes in South America, and the Himalaya in Asia.
Figure 19.2: The Fraser Glacier in Glacier Bay National Park, Alaska is a valley glacier, confined by mountains on either side. (Public Domain; Jacob W. Frank/NPS Links to an external site.)
Piedmont glaciers Links to an external site. form where steep valley glaciers spill onto relatively flat plains and spread out into bulb-like lobes.
Ice sheets Links to an external site. are enormous continental masses of glacial ice and snow expanding over 50,000 square kilometers (19,305 square miles). Currently, the only ice sheets are found in Antarctica Links to an external site. and Greenland Links to an external site. (Figure 19.3). Ice caps Links to an external site. are miniature ice sheets, covering less than 50,000 square kilometers (19,305 square miles) and forming primarily in polar and subpolar regions.
Figure 19.3: Earth’s current ice sheets, Greenland and Antarctica. (CC-BY 4.0, Chloe Branciforte via Google Earth)
Ice shelves Links to an external site. occur when ice sheets extend over the sea and float on the water. They range from a few hundred meters to over 1 kilometer (0.62 mile) in thickness. Ice shelves surround most of the Antarctic continent. Sea ice Links to an external site. is NOT a glacier, as glaciers develop only on land; however, much of the world's sea ice is enclosed within the polar regions.