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Juneau Icefield
From Wikipedia, the free encyclopedia
The Juneau Icefield or Juneau Icecap is an ice field located just north of Juneau, Alaska and continues north through the border with British Columbia and the fifth-largest ice field in the Western Hemisphere[1].
The Juneau Icefield is the fifth largest icefield in North America extending through an area of 3,900 square kilometers in the Coast Range ranging 140 km north to south and 75 km east to west. The icefield is the source of a myriad of glaciers including the famous "drive-up" Mendenhall Glacier and the aggressive Taku Glacier. The icefield in fact is home to over 40 large valley glaciers and 100 smaller ones. The Icefield serves as a tourist attraction with many travellers flown in by helicopter for quick walks on the 240 to 1,400 meter deep ice and the massive, awe-inspiring crevasses. The icefield, like many of its glaciers, reached its maximum glaciation point around 1700 and has been decreasing in size since. In fact, of the icefield's 19 notable glaciers, the Taku Glacier is the only one presently advancing.
Since 1948, the Juneau Icefield Research Program has monitored glaciers of the Juneau Icefield. On the west side of the icefield, from 1946-2005, the terminus of the Mendenhall Glacier has retreated 580 meters.
Eight kilometers to the north, the Herbert Glacier has retreated 540 meters, while Eagle Glacier retreated 700 meters, Gilkey Glacier 3,500 meters and Llewellyn Glacier 2,800 m. On the south side of the icefield, the Norris Glacier retreated 1,740 meters, the East Twin Glacier 1,100 meters, and the West Twin Glacier 570 meters. Only the Taku Glacier has advanced. Surveys reveal the Taku as one of the deepest glaciers of the sub-temperate icefields surveyed at nearly 1,370 m thick. This glacier was advancing in 1890 when viewed by John Muir and had a large calving front. By 1963 the glacier had advanced 5.6 km. In 1948 the Taku Fjord had been completely filled in with glaical sediment and the glacier no longer calved. From 1948-1986 the glacier had a positive glacier mass balance driving the advance. From 1987-2005 the glacier has had a slightly negative mass balance, not enough to end the advance, but if it continues will soon slow it.
A notable peak in the Juneau Icefield is Devils Paw.