Sperry Glacier

Sperry Glacier
Sperry Glacier beneath snowy Gunsight Mountain - September 8, 2008
Type	Mountain glacier
Location	Glacier National Park, Flathead County, Montana, United States
Coordinates	48°37′23″N 113°45′44″W / 48.62306°N 113.76222°W / 48.62306; -113.76222[1]
Area	216 acres (0.87 km2) in 2005[2]
Terminus	Talus
Status	Retreating

Sperry Glacier is a glacier on the north slopes of Gunsight Mountain west of the Continental Divide in Glacier National Park in the U.S. state of Montana.^[3] Although many geologic features of Glacier National Park were formed during the much longer period of glaciation ending over 10,000 years ago, Sperry Glacier — like all the glaciers in the park today — is a product of the recent Little Ice Age, the period of cooler average temperatures starting in about the 13th century and concluding in the mid-19th century.

Once one of the largest glaciers in the park, the surface area of Sperry Glacier has retreated 75 percent since the mid-19th century. 2005 measurements of the surface area of the glacier resulted in an estimated area of 216 acres (0.87 km²), whereas the glacier is estimated to have covered an area of 930 acres (3.8 km²) at the end of the Little Ice Age in the mid-19th century. The glacier lost almost 35 percent of its surface area between 1966 and 2005.^[2] The glacier is named for Lyman B. Sperry, a professor from Oberlin College, who in 1895 participated in an expedition to explore the geography and map the region where the glacier is located.^[4] Like all other glaciers in the park, Sperry has significantly retreated, though it leaves many minor glacial features, including large moraines and streams and lakes colored a milky aqua from glacial flour. Unlike the more famous Grinnell Glacier, Sperry Glacier is high above the lakes it feeds, so no icebergs form.