July 9, 2018
Glaciers Abandon Farragut River Valley, Alaska
Posted by Mauri Pelto
The Farragut Glacier (F) in Landsat images in 1985 and 2017. The red arrow indicates the 1985 terminus location, the yellow arrow the 2017 terminus location and the purple arrow, two tributaries in 1985 that now no longer connect to the former valley glacier. The glacier now terminates well short of Glory Lake (G) and two new lakes have formed.
The Farragut River drains into Frederick Sound in Southeast Alaska. The headwaters of this river in 1985 was a valley glacier, Farragut Glacier, fed by seven glaciers descending from peaks on the south wall of the valley or flowing down from the Stikine Icefield. The river is known for significant Pink and chinook salmon runs as well. This valley is just to the north of Baird Glacier that has begun to retreat.
In the USGS map from 1975 there are seven glaciers that drain into the valley bottom contributing to the Farragut Glacier, see map below. The glacier at this time terminated in Glory Lake. By 1985 the glacier had retreated 1.2 km from Glory Lake and was 7.2 km long. There was a medial moraine that had expanded in width and height indicating the glacier tongue was thinning rapidly. The overflow tributaries from Dawes and North Baird Glacier, purple arrows, still connected to the valley glacier. By 1993 thinning and retreat had led to formation of a new lake. The overflow tributaries from Dawes and North Baird Glacier no longer reach Farragut Glacier. By 2016 vegetation there are two new lakes where the Farragut Glacier used to be. New vegetation has developed where the tributary from Dawes and North Baird Glacier formerly joined the Farragut Glacier. By 2017 there is only a single tributary that contributes to the Farragut Glacier, which occupies only a small segment of the valley floor. The distance from this tributary to the terminus is 3.1 km. The glacier has lost most of its length, six of its former glacier connections and two lakes have developed in 32 years of retreat and thinning. The Farragut River valley has largely been abandoned by glaciers in the last three decades. The thinning and retreat is larger here than at Baird Glacier and Patterson Glacier
The Farragut Glacier (F) in Landsat images in 1993 and 2016. The red arrow indicates the 1985 terminus location, the yellow arrow the 2017 terminus location and the purple arrow, two tributaries in 1985 that now no longer connect to the former valley glacier.
USGS map indicating the seven glaciers that connect to make the Farragut Glacier in 1948.
Google Earth Image indicating the two lakes and the one tributary that reaches the Farragut River valley floor.