Mount Rainier National Park

Mt. Rainier viewed from White Pass in winter

Glaciers form when more snow accumulates than melts away over a long period of time. As snow continues to accumulate, year after year, the lower layers are compressed into very thick ice. From a distance, glacial ice has a characteristic bluish color. There are 25 named glaciers and numerous small, unnamed glaciers and ice patches on the slopes of Mount Rainier. The total volume of ice and snow on Mount Rainier has been estimated at about one cubic mile. It has as much snow and ice on its slopes as all of the other Cascade volcanoes combined!

What is the difference between glaciers and snowfields? Glaciers are gradually being pulled downhill by the force of gravity. On Mount Rainier, the glaciers flow down the sides of the mountain, melting at the lower ends while more snow accumulates at the upper ends. Snowfields, on the other hand, melt on warm days and grow larger during snowy winters, but they do not flow downhill. They may sit on flat areas, or they may be surrounded by ridges or hills that hold them in place.

Glaciers advance (grow in size) or retreat (shrink in size) in response to changes in climate over a period of several years. Glacier size, thickness, and length can be sensitive indicators of climate change. The Nisqually Glacier on Mount Rainier has been studied since 1918, when scientists began to measure the position of its terminus, or lowest part. This is the longest record of study on any glacier in the Western hemisphere. In 1931, scientists began to take measurements to determine the glacier's thickness.

The glaciers on Mount Rainier are the sources of five major river systems: Nisqually, Cowlitz, White, Carbon, and Puyallup. These rivers provide water for plants, animals, and humans throughout western Washington. When you visit Mount Rainier National Park, look for these rivers and notice how muddy they look. The mud they carry is finely ground rock scratched by moving glaciers from the shoulders of Mount Rainier.

Glacier Facts

Mount Rainier's elevation: 14,410 feet

Number of named glaciers on Mount Rainier: 25

Glaciers that start at the summit: Emmons, Nisqually, Winthrop, Tahoma, Ingraham

Area covered by permanent snow: 22,747 acres (glaciers and snow patches)

Longest and thickest glacier on Mount Rainier: Carbon Glacier, 5.7 miles long and 700 feet thick. Its 3,500-foot elevation terminus is the lowert of any glacier in the Unitied States.

Fastest measured movement downhill for a Mount Rainier glacier: Nisqually Glacier, 29 inches per day

Largest surface area of any glacier in the contiguous United States: Emmons Glacier (4.3 square miles)

Watersheds fed by streams running off Mount Rainier: 9


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