AdvanceGlacier flow exceeds ablation, and the terminus extends farther down valley than previously
CalveProcess of ice breaking off at a glacier's terminus
CrevasseA large crack in the surface of a glacier produced by the stress of glacial flow
HangingA glacier that clings to the side of a steep mountain or one that terminates at a cliff
MoraineA deposit of rock debris shaped by glacial flow and erosion
TidewaterA glacier that terminates in the sea and discharges icebergs and other small pieces of ice
TerminusThe lower end, or snout, of a glacier
Glaciers in Alaska's National Parks
Approximately one fourth (4.6 million acres) of Alaska's glaciers occur within national parks. Glaciers require three conditions to form: abundant snowfall, cool summers, and the gravitational flow of ice. Glaciers form in land areas where annual snow fall is greater than annual snow melt. Some areas in Alaska, such as the Harding Icefield in Kenai Fjords National Park, receives an average of 60 feet of snow each year. Large amounts of snowfall, combined with cool summers and gravity, form multiple, connected glaciers, known as an icefield, over time.
The Science of Glaciers
Glaciers are fascinating natural features and the subject of study for many scientists within the national parks of Alaska.
Glaciers and Climate Change
Most of Alaska's glaciers have been retreating over the last century, and reserach shows that the rate of recession has increased significantly in recent years. The effects of melting glaciers are not yet fully understood. However, given the tremendous amount of water stored in glaciers, the impacts on fresh water flow, vegetation, and coastal marine ecosystems wil likely be of great significance.
The History of Glaciers
Glaciers tell stories of the earth's history. Glaciers shape the earth's surface as they move and form valleys, mountains and other large formations. Glacial ice documents weather and life from many years past. The rich, diverse ecosystems provide food and a home for people.
Live Chat with Glacier Experts
On February 8, 2012, glacier experts with the National Park Service hosted a virtual open forum and answered questions from the public via Facebook, Twitter, and email. The script of questions, answers and posts is available for download. Video introductions of all the experts can be viewed on the videos page of this site.