GLACIAL ADVANCE ON MOUNT BAKER

The Coleman Glacier on Mt. Baker, a 10,750-foot volcanic peak in Washington State, occupies on the north the natural depression formed at the junction of the present summit cone and an older volcanic cone somewhat to the side. It extends from the summit of the mountain down to about the 4,000-foot level and was first observed to be advancing in 1949. This year a visit in late September to the glacier showed the advance to be continuing and accelerating. Considerable thickening of the Coleman has occurred since last year at 6,000 feet, thickening has occurred at 4,900 feet despite the dry, sunshiny summer, and the terminus has pushed another 250 feet down valley for a total advance along the surface of the ground of about 1,000 feet since 1949. Late in September the glacier surface was still covered with last year’s snow down to about 5,800 feet. This means more snow was received than melted on about 80 per cent of the glacier surface and assures that the advance will continue at least one or two more seasons.

The adjoining Roosevelt Glacier has advanced to a series of lava cliffs formerly 500 to 700 feet removed from the Roosevelt terminus. Enormous ice avalanches, due to séracs being pushed over the lava cliffs, were enjoyed at a comfortable distance by the September observing party from the vantage point of Bastille Ridge to the east of both the Coleman and Roosevelt Glaciers. The observing party while on Bastille Ridge laid out a photo- grammetric base line 662.1 feet in length, did the necessary control surveying, and made stereoscopic pairs of photographs of the entire glacier system, using the University of Washington’s T.A.F. photo-theodolite. These pairs of photographs are now in Munich, Germany, where Dr. Ing. Walther Hofmann is constructing a detailed topographic map of the area from them. Such a map will be used with future data to calculate changes in ice volume of the glacier.

The advance of the Coleman and Roosevelt Glaciers may indicate something worthy of much more than passing interest on the part of mountaineers. Last summer R. Hubley1 found that many glaciers in the North Cascades and in the Olympics are advancing. Some, particularly in the Glacier Peak area, are advancing as spectacularly as the Coleman. This widespread increase in glacial activity indicates that the trend toward a warmer and drier climate, which has been world-wide since the latter part of the 19th century, has been reversed in the northwestern United States. How long the reversal will continue, how severe it will become, and how extensive it will be can only be determined as observers the world over continue to make observations of glacial activity.

Kermit B. Bengston

1Hubley, R. C., Journal of Glaciology, In Press, 1956, "Glaciers of the Washington Cascade and Olympic Mountains; Their Present Activity and Its Relation to Local Climatic Trends.”