Studies in the Sierra. No. IV.-Glacial Denudation.
STUDIES IN THE SIERRA By John Muir NO. IV. GLACIAL DENUDATION GLACIAL denudation is one of the noblest and simplest manifestations of sun-power. Ocean water is lifted in vapor, crystallized into snow, and sown broadcast upon the mountains. Thaw and frost, combined with the pressure of its own weight...
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Scholarly Commons
1918
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| Online Access: | https://scholarlycommons.pacific.edu/jmb/400 https://scholarlycommons.pacific.edu/context/jmb/article/1399/viewcontent/349.pdf |
| Summary: | STUDIES IN THE SIERRA By John Muir NO. IV. GLACIAL DENUDATION GLACIAL denudation is one of the noblest and simplest manifestations of sun-power. Ocean water is lifted in vapor, crystallized into snow, and sown broadcast upon the mountains. Thaw and frost, combined with the pressure of its own weight, change it to ice, which, although in appearance about as hard and inflexible as glass, immediately begins to flow back toward the sea whence it came, and at a rate of motion about equal to that of the hour-hand of a watch. Fig. i. This arrangement is illustrated in Fig. I, wherein a wheel, constructed of water, vapor, snow, and ice, and as irregular in shape as in motion, is being sun-whirled against a mountainside with a mechanical wearing action like that of an ordinary grindstone. In north Greenland, Nova Zembla, the arctic regions of Southeastern Alaska and Norway, the snow supply and general climatic conditions are such that their glaciers discharge di- sieRR A CLUB BULLETIN, VOL. X. PLATE OLD JUNIPER, OVER TEN FEET AT BASE On Tamarack Trail, Ralston Peak in distance Photo by Harold C. Bradley SIERRA CLUB BULLETIN VOL. X. GIANT JUNIPER IN CATHEDRAL CANON YOSEMITE NATIONAL PARK Photo by William E. Colby Studies in the Sierra 305 rectly into the sea, and so perhaps did all first-class glaciers when in their prime; but now the world is so warm, and the snow-crop so scanty, most glaciers melt long before reaching the ocean. Schlagenweit tells us those of Switzerland melt on the average at an elevation of about 7400 feet above sea-level; the Himalaya glacier, in which the Ganges takes its rise, does not descend below 12,914 feet while those of our Sierra melt at an average elevation of about 11,000 feet. In its progress down a mountain-side a glacier follows the directions of greatest declivity, a law subject to very important modifications in its general application. Subordinate ranges many hundred feet in height are frequently overswept smoothly and gracefully without any visible manifestations of power. Thus, ... |
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