ABSTRACT
Glaciers are scattered from 38°15´N in southern California to the arctic islands of northern Canada, from the Colorado Front Range and the mountains of Wyoming to the maritime coastal mountains of the northwestern United States, and from Alaska and the Yukon to the eastern Canadian Arctic (Figure 9.1). The many thousands of glaciers include representatives of nearly all the topographical and physical types. Tiny glaciers in the Sierra Nevada, none covering more than 2 km2, nestle in deep cirques or beneath north-facing cliffs, well below the orographic snowline (Raub et al. 1980). In 1975 W. O. Field calculated that ice in the Pacific Mountain systems of Alaska and the Yukon covered over 100,000 km2, some 18 per cent of the glacierized area of the northern hemisphere apart from Greenland.
