Type Mountain glacier Terminus Icefall | Length 1 mi (1.6 km) Status Retreating | |
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Location North Cascades National Park, Skagit County, Washington, United States | ||
Boston Glacier is located in a large cirque below several mountain peaks in North Cascades National Park in the U.S. state of Washington. The glacier is approximately 1 mi (1.6 km) long but nearly 3.5 mi (5.6 km) wide and is the largest glacier in North Cascades National Park. Extending in an arc from the north of Forbidden Peak, the glacier is also flanked by Boston Peak to the southwest and Buckner Mountain at its eastern margin. Between Boston Peak and Buckner Mountain, the glacier lies below the arête known as Ripsaw Ridge. Another arete extending between Boston Mountain and Forbidden Peak and further north separate Boston Glacier from the nearly adjoining Quien Sabe and Forbidden Glaciers. Boston Glacier has been in an overall state of retreat since the end of the Little Ice Age around the year 1850. A moderate advance occurred between 1950 and the mid-1970s however the retreat resumed and between the years 1972 and 2006 the glacier terminus retreated 1,470 ft (450 m).