|
The Juneau Icefield is an ice field located just north of Juneau, Alaska and continues north through the border with British Columbia and is the fifth-largest ice field in the Western Hemisphere,〔http://www.juneauicefield.com/〕 extending through an area of in the Coast Range ranging north to south and east to west. The icefield is the source of many glaciers including the Mendenhall Glacier and the Taku Glacier. The icefield 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 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 in retreat since. In fact, of the icefield's 19 notable glaciers, the Taku Glacier is the only one presently advancing. Much of the icefield is contained within the Tongass National Forest. Since 1948, the Juneau Icefield Research Program has monitored glaciers of the Juneau Icefield. On the west side of the icefield, from 1946-2009, the terminus of the Mendenhall Glacier has retreated over . Eight kilometers to the north, the Herbert Glacier has retreated , while Eagle Glacier retreated , Gilkey Glacier and Llewellyn Glacier . On the south side of the icefield, the Norris Glacier retreated , the East Twin Glacier , the West Twin Glacier with only the Taku Glacier advancing. Surveys reveal the Taku as one of the deepest glaciers of the sub-temperate icefields surveyed at nearly thick. This glacier was advancing in 1890 when viewed by John Muir and had a large calving front. By 1963 the glacier had advanced . In 1948 the Taku Fjord had been completely filled in with glacial sediment and the glacier no longer calved. From 1948–1986 the glacier had a positive glacier mass balance driving the advance. From 1987–2009 the glacier has had a slightly negative mass balance, not enough to end the advance, but if it continues will soon slow it. Notable peaks on the Juneau Icefield are Devils Paw and the Mendenhall Towers. ==See also== *List of glaciers and icefields *Retreat of glaciers since 1850 *Ha-Iltzuk Icefield *Homathko Icefield *Lillooet Icecap 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Juneau Icefield」の詳細全文を読む スポンサード リンク
|