File:American forestry (1910-1923) (17522995414).jpg

Title: American forestry
Identifier: americanforestry201914amer (find matches)
Year: 1910-1923 (1910s)
Authors: American Forestry Association
Subjects: Forests and forestry
Publisher: Washington, D. C. : American Forestry Association
Contributing Library: The LuEsther T Mertz Library, the New York Botanical Garden
Digitizing Sponsor: The LuEsther T Mertz Library, the New York Botanical Garden

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THE GLACIERS OF MT. RAINIER 661 Crater Lake. The lakelets observed in the neighboring valley heads—all of which are abandoned cirques—are of similar origin. It is a significant fact that the empty cirques about the Mother Mountains lie at elevations ranging between 4,500 and 6,00 feet; that is, on an average 5,000 feet lower than the cirques on Mount Rainier which now produce glaciers. Evidently the snow line in glacial times lay at a much lower level than it does today, and the ice mantle of Mount Rainier expanded not merely by the forward lengthening of its ice tongues but bt the birth of numerous new glaciers about the mountain's foot. The large size of the empty cirques and can- yons, moreover, leads one to infer that many of these new glaciers far exceeded in volume the ice streams descending the volcano's sides. The latter, it is true, increased considerably in thickness dur- ing glacial times, but not in proportion to the growth of the low-level glaciers. Nor is this surprising in view of the heavy snowfalls occuring on the moun- tain's lower slopes. There is good reason to believe, moreover, that the cool glacial climate resulted in a general lowering of the zone of heaviest snowfall. It probablv w^as depressed to levels be- tween 4,000 and 6,000 feet. Not only the cirque glaciers about the Mother Mountains, but all the neighboring ice streams of the glacial epoch originated within this zone, as is indicated l)y the altitudes of the cirques throughout the adjoining portions of the Cascade Range. By their confluence these ice bodies pro- duced a great system of glaciers that filled all the valleys of this mountain belt and even protruded beyond its western front. To these extensive valley glaciers the ice flows of Mount Rainier stood in the relation of mere tributaries. They descended from regions of rather scant snowfall, for the peak in those daj^s of frigid cHmate rose some 10,000 feet above the zone of heaviest snowfall, into atmospheric strata of relative dryness. It may well be, indeed, that it carried then but little more snow ujion its summit than it does todav.
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