The Glaciation Level in Southern Alaska

ABSTRACT

There exists a critical altitude in mountainous areas termed “the glaciation level”. Mountains with a summit higher than this altitude will normally collect enough snow to produce a glacier—lower mountains will not.

Maps showing the height of the glaciation level have been constructed at a scale of 1:2 000 000 for Western North America. In this paper the third in a series is presented together with a combined map (1:4 000 000) covering Western Canada and Southern Alaska.

The height of the glaciation level (previously termed glaciation limit) is mainly related to winter precipitation and summer temperature. A map showing isohyets for Southern Alaska is compared with the map of the glaciation level. Similar comparisons are made with the summer temperature variations—after reduction to the height of the glaciation level, and certain relations are found.

It is concluded that the best explanation for variations in the height of the glaciation level is the variation in winter precipitation. Higher snowfall produces a lower glaciation level and vice versa. Topography may channel oceanic air masses far inland, thus depressing the glaciation level, demonstrated by embayments in the isoglacihypses shown on the maps.