Geological Survey 18th Annual Report (Part II) Glaciers of Mount Rainier Rocks of Mount Rainier

INGRAHAM GLACIER.

The portion of the névé descending the east side of the central dome of Mount Rainier, to the right or south of Little Tahoma, and divided by that promontory from the portion of the névé tributary to Emmons Glacier, forms a primary glacier of an abnormal type. This well-defined ice stream does not descend the mountain slope in direct course, but is deflected southward or becomes tributary to Cowlitz Glacier. Its course is oblique to what may be considered the normal flow of a primary glacier originating on an isolated peak.

Where the descending névé is split by the sharp edge of the great wedge-shaped remnant of the side of the mountain, of which Little Tahoma is the culminating peak, the ice rises against the rocks and is greatly shattered. The portion of the névé turned southward by the obstruction now descends a steep slope and is much crevassed; below the slope the descent is more gentle, and the hard, blue ice, but little encumbered with débris, flows on as a well-defined glacier. All along the left side of the glacier the cliffs of Little Tahoma rise in rugged precipices, from which débris is continually falling. On approaching its junction with Cowlitz Glacier, Ingraham Glacier descends a precipice about 800 feet high and forms a fine ice cascade. Something of the appearance of this steep ice-covered descent is shown in the accompanying illustration (Pl. LXXV), in which the head of Cowlitz Glacier and the bold cliffs of bedded lava and agglomerate between the two glaciers are also shown. In this illustration, also, the bedded character of the rocks forming Little Tahoma, and the manner in which the irregular strata end in the air on the left—that is, toward the summit of Mount Rainier—may be recognized. Before erosion altered the topography of the mountain, and previous to the blowing away of its summit, the strata in Little Tahoma were continued upward to the summit of the perfect volcanic cone.

The illustration to which attention has been directed is unsatisfactory on account of its "flatness." The distance from the rocks in the foreground, across Cowlitz Glacier, to the cliff of inclined beds between the two ice falls is fully a mile. The peak of Little Tahoma is about 3 miles distant. With these measures in mind the photograph reproduced in Pl. LXXV becomes more intelligible.

COWLITZ GLACIER.

The Cowlitz Glacier, above where Ingraham Glacier joins it, expands somewhat and occupies an irregular depression, having some of the features of an amphitheater. The slopes at the head of the depression are so sharp that the snow descends in avalanches. The main portion of the névé is comparatively low on the mountain side, but some of the snow drainage comes from near the summit. The valley occupied by the névé contracts just above where Ingraham Glacier comes in, and it is there that the lower limit of the névé probably occurs, but at the time of our visit the glacier was snow-covered and white as far down its course as we were able to see. The snowfall during the winter preceding our visit was unusually heavy, especially on the south side of the mountain, and the melting of the snow in spring was long delayed. Photographs taken in previous years (Pl. LXXVI) show that ordinarily in late summer the solid glacial ice is exposed and forms an extremely rugged, dirt-covered surface, where we walked with ease over hard snow.

Pl. LXXVII. NISQUALLY GLACIER.

The portion of Cowlitz Glacier below Ingraham Glacier is inclosed by bold cliffs, and is well defined. There is less evidence of shrinkage along its sides than in the case of the other glaciers examined. This is possibly due in part to the fact that Ingraham Glacier has a high grade and probably conducts away much of the snow that might be considered as belonging to Emmons Glacier. A sharp-crested lateral moraine across a side expansion of the valley, a mile below Ingraham Glacier, is evidence, however, of a recent lowering of the surface of at least 75 or 100 feet.

The lower portion of Cowlitz Glacier was not seen by me, but, judging from what I observed, I should say that it furnishes the most typical example of an Alpine glacier that exists about Mount Rainier. It is readily accessible from Paradise Park, and could conveniently be made the subject of special study.

NISQUALLY GLACIER.

The Nisqually Glacier flows past Paradise Park on the west, and as this beautiful region is visited each summer by hundreds of tourists, it is, in a general way, the best known of the glaciers on Mount Rainier. My visit to the southern side of the mountain was too brief, however, to admit of my becoming acquainted with the glacier that is so familiar to many others, and instead of attempting a description of it I wish rather to suggest observations that visitors to Paradise Park may easily make.

Nisqually Glacier heads in two névé fields, which occupy what may be termed incipient amphitheaters, situated below the level of Gibraltar. Each of these depressions receives snow from avalanches that descend the steep slopes above them. The easterly névé, the one nearest Gibraltar, however, is fed by two snow streams, which endure through the summer, and from ice cascades, on which small avalanches frequently occur. These features are shown on Pl. LXXVII, which also illustrates the manner in which the glacier is crevassed and the extent of the sheet of débris covering its borders just below where the two névés unite. In this same region there are several small ice domes, one of which may be recognized in Pl. LXXIX. Visitors to Paradise Park could render assistance to students of glaciers by obtaining good photographs of this ice dome from time to time, and thus furnishing a record of the changes it passes through. By boring 2-inch auger holes to a depth of 6 or 8 feet in the ice and inserting vertical stakes,the daily rate of surface melting could be measured. A row of such stakes placed in line across the glacier would furnish a means of measuring the flow of the ice.

The Nisqually Glacier narrows to a well-defined stream to the west of Paradise Park, and at its terminus there is an archway from which Nisqually River rushes out. Photographs of the terminus taken at several dates during the summer from the same point of view—which should be so marked that it could be rediscovered year after year, for the purpose of obtaining additional pictures—would furnish data for ascertaining the advances and recessions of the glacier. To aid in these observations records should be made on the cliffs, either by chiseling into the rock or by painting an appropriate mark upon it, which would mark the position of the ice front at a definite time and admit of measurement of the fluctuations of the end of the glacier in subsequent years.¹

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¹A committee of the International Congress of Geologists was appointed in 1894 for the purpose of recording observations of the nature above suggested. Prof. H. Fielding Reid, of Johns Hopkins University, Baltimore, Maryland, is a member of this committee, and will furnish instructions for making the desired observations. Photographs, or other data concerning the fluctuations of glaciers, forwarded to Professor Reid will be carefully preserved and utilized to the best advantage, full credit being given those furnishing the information. See the Journal of Geology, Vol. III, 1895, p. 284.

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Nisqually Glacier affords abundant opportunity for observing and studying the various minor features that glaciers present, such as the nature of crevasses, and their different types; the nature and origin of moraines; the manner in which lateral moraines are left stranded on the sides of a valley by the lowering of the ice; glacial tables, and the changes they pass through during the season of melting; sand cones; débris pyramids, etc. The delights of camp life in Paradise Park can be greatly enhanced by anyone who chooses to avail himself of the advantages for glacier study there afforded.

The glaciers on the southwest side of Mount Rainier have not been seen by me, and no data are available concerning them except such as are given on the accompanying map.