Nature Notes

Vol. X July, 1932 No. 7


Remnants of an age in the distant past - as we would measure time - are Rainier's great rivers of ice. But geologists will tell us that the years that have slipped past since that ice sheet had nudged its way down into the Puget Sound region from the North might, geologically, be compared to a few ticks of a clock. Then the ice sheet that clothed this mountain was, of course, much larger and possibly merged with the ice which then laid over much of the country about Seattle, Tacoma, and nearby towns to a point in the vicinity of the town of Tenino. This ice invasion has been forced back to the North but here and there upon the great mountains of the northwest we still find remnants of considerable size that still speak eloquently of the ice age.

Most accessible and most important of these are the glaciers of Mt. Rainier. Here we have the largest glacial system in the Union -- twenty-eight claciers of varying magnitude from small pockets of ice and perpetual snow to long tongues several miles in length that sweep down from the summit or from cirques just below the summit through narrow gorges to more moderate climes near the base of the Mountain. This system contains a surface measure of nearly fifty square miles, a sizeable area to be overlaid by ice.

That Rainier's glaciers are receding is self-evident. Just as the ice sheet receded and, possibly, is still receding, so these glaciers on "The Mountain" are being pushed slowly higher toward their point of origin. Recessional measurements of several of the major glaciers here are taken annually and we know that the Nisqually Glacier, which as been the subject of such studies for a longer period of time than any other, is now receding at an annual rate of approximately 70 feet each year.

sketch of ice cave

Ice caverns, such as are fond in "dead" glaciers, are characteristic of the Paradise Glacier. Parties visit these remarkable phenomona daily under leadership of Government Naturalists.

And this is in spite of the fact that there is a downward movement of - on hot summer days - nearly fifteen inches. Those glaciers which have a downward movement are known as live glaciers, as they are continuing the processes which cause such ice sheets to mould the landscape in various ways. As they move downward they gouge deep into the mountain's flanks, under-cut the walls of the canyons which they have formes and bring rock and debris showering down upon them. Such activity was the cause of the formation of the glacial cirques, of the broad, U-shaped valleys similar to the Paradise Valley below Sluiskin Falls, through which the Paradise River flows, and gives the milky color to the streams of glacial origin through the summer months. Too, it accounts for the black - and often disappointing - appearance of the ice near the snout or terminus of the glacier, for many thing of glacial ice as totally crystal-clear. But even though it may at first be disappointing one sees evidence of the great power of this moving ice in that dirty mixture. Crevasses are the most spectacular features of these living, moving glaciers, and they likewise owe their origin to this movement, for, as the ice passes over irregularities, it must needs give and crack under the strain and stresses set up in that manner.

sketch of crevass

Government naturalists visit these living glaciers as well as the dead glaciers with parties from Paradise Valley. And no one seeking an understanding of glaciers and the manner in which they mould the face of the earth should fail to visit a representative glacier of each type. For the dead glacier does not move. Once, perhaps, its bulk was sufficient so that it, too, was a living ice sheet. But generally speaking it has backed up into its cirque and melts away more rapidly. Here one finds ice caverns rather than crevasses, and it is possible within these caves to view a glacier from the underside, and note the results that have accrued from the activity of warm air currents sweeping along the water courses that flow from the ice.

There are glacierss of varying beauty and magnificence, of several different types, on Mt. Rainier. Each is worth more than a hasty, distant glance.

Yawning Crevasses, treacherous places for the unskilled, are found on "Living", or moving glaciers.

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