John Muir: Wilderness Essays, Environmental Studies, Memoirs & Letters (Illustrated Edition). John Muir
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nine thousand feet above sea level. Some are miles in extent, only slightly blurred or scarred by spots that have at last yielded to the weather; while the best preserved portions are brilliantly polished, and reflect the sunbeams as calm water or glass, shining as if rubbed and burnished every day, notwithstanding they have been exposed to plashing, corroding rains, dew, frost, and melting sloppy snows for thousands of years.
The attention of hunters and prospectors, who see so much in their wild journeys, is seldom attracted by moraines, however regular and artificial-looking; or rocks, however boldly sculptured; or cañons, however deep and sheer-walled. But when they come to these pavements, they go down on their knees and rub their hands admiringly on the glistening surface, and try hard to account for its mysterious smoothness and brightness. They may have seen the winter avalanches come down the mountains, through the woods, sweeping away the trees and scouring the ground; but they conclude that this cannot be the work of avalanches, because the stri show that the agent, whatever it was, flowed along the around and over the top of high ridges and domes, and also filled the deep cañons. Neither can they see how water could be the agent, for the strange polish is found thousands of feet above the reach of any conceivable flood. Only the winds seem capable of moving over the face of the country in the directions indicated by the lines and grooves.
The pavements are particularly fine around Lake Tenaya, and have suggested the Indian name Py-we-ack, the Lake of the Shining Rocks. Indians seldom trouble themselves with geological questions, but a Mono Indian once came to me and asked if I could tell him what made the rocks so smooth at Tenaya. Even dogs and horses, on their first journeys into this region, study geology to the extent of gazing wonderingly at the strange brightness of the ground, and pawing it and smelling it, as if afraid of falling or sinking.
In the production of this admirable hard finish, the glaciers in many places exerted a pressure of more than a hundred tons to the square foot, planing down granite, slate, and quartz alike, showing their structure, and making beautiful mosaics where large feldspar crystals form the greater part of the rock. On such pavements the sunshine is at times dazzling, as if the surface were of burnished silver.
Pavement of basaltic columns worn by glacial action, Yosemite
Here, also, are the brightest of the Sierra landscapes in general. The regions lying at the same elevation to the north and south were perhaps subjected to as long and intense a glaciation; but because the rocks are less resisting, their polished surfaces have mostly given way to the weather, leaving here and there only small imperfect patches on the most enduring portions of cañon walls protected from the action of rain and snow, and on hard bosses kept comparatively dry by boulders. The short, steeply inclined canons of the east flank of the range are in some places brightly polished, but they are far less magnificent than those of the broad west flank.
One of the best general views of the middle region of the park is to be had from the top of a majestic dome which long ago I named the Glacier Monument. It is situated a few miles to the north of Cathedral Peak, and rises to a height of about fifteen hundred feet above its base and ten thousand above the sea. At first sight it seems sternly inaccessible, but a good climber will find that it may be scaled on the south side. Approaching it from this side you pass through a dense bryanthus-fringed grove of mountain hemlock, catching glimpses now and then of the colossal dome towering to an immense height above the dark evergreens; and when at last you have made your way across woods, wading through azalea and ledum thickets, you step abruptly out of the tree shadows and mossy leafy softness upon a bare porphyry pavement, and behold the dome unveiled in all its grandeur. Fancy a nicely proportioned monument, eight or ten feet high, hewn from one stone, standing in a pleasure ground; magnify it to a height of fifteen hundred feet, retaining its simplicity of form and fineness, and cover its surface with crystals; then you may gain an idea of the sublimity and beauty of this ice-burnished dome, one of many adorning this wonderful park.
In making the ascent, one finds that the curve of the base rapidly steepens, until one is in danger of slipping; but feldspar crystals, two or three inches long, that have been weathered into relief, afford slight footholds. The summit is in part burnished, like the sides and base, the stri and scratches indicating that the mighty Tuolumne Glacier, two or three thousand feet deep, overwhelmed it while it stood firm like a boulder at the bottom of a river. The pressure it withstood must have been enormous. Had it been less solidly built, it would have been ground and crushed into moraine fragments, like the general mass of the mountain flank in which at first it lay imbedded; for it is only a hard residual knob or knot with a concentric structure of superior strength, brought into relief by the removal of the less resisting rock about it,--an illustration in stone of the survival of the strongest and most favorably situated.
Hardly less wonderful, when we contemplate the storms it has encountered since first it saw the light, is its present unwasted condition. The whole quantity of postglacial wear and tear it has suffered has not diminished its stature a single inch, as may be readily shown by measuring from the level of the unchanged polished portions of the surface. Indeed, the average postglacial denudation of the entire region, measured in the same way, is found to be less than two inches,--a mighty contrast to that of the ice; for the glacial denudation here has been not less than a mile; that is, in developing the present landscapes, an amount of rock a mile in average thickness has been silently carried away by flowing ice during the last glacial period.
A few erratic boulders nicely poised on the founded summit of the monument tell an interesting story. They came from a mountain on the crest of the range, about twelve miles to the eastward, floating like chips on the frozen sea, and were stranded here when the top of the monument emerged to the light of day, while the companions of these boulders, whose positions chanced to be over the slopes where they could not find rest, were carried farther on by the shallowing current.
The general view from the summit consists of a sublime assemblage of iceborn mountains and rocks and long wavering ridges, lakes and streams and meadows, moraines in wide-sweeping belts, and beds covered and dotted with forests and groves,--hundreds of square miles of them composed in wild harmony. The snowy mountains on the axis of the range, mostly sharp-peaked and crested, rise in a noble array along the sky to the eastward and northward; the gray-pillared Hoffman spur and the Yosemite domes and a countless number of others to the westward; Cathedral Peak with its many spires and companion peaks and domes to the southward; and a smooth billowy multitude of rocks, from fifty feet or less to a thousand feet high, which from their peculiar form seem to be rolling on westward, fill most of the middle ground. Immediately beneath you are the Big Tuolumne Meadows, with an ample swath of dark pine woods on either side, enlivened by the young river, that is seen sparkling and shimmering as it sways from side to side, tracing as best it can its broad glacial channel.
The ancient Tuolumne Glacier, lavishly flooded by many a noble affluent from the snow-laden flanks of Mounts Dana, Gibbs, Lyell, Maclure, and others nameless as yet, poured its majestic overflowing current, four or five miles wide, directly against the high outstanding mass of Mount Hoffman, which divided and deflected it right and left, just as a river is divided against an island that stands in the middle of its channel. Two distinct glaciers were thus formed, one of which flowed through the Big Tuolumne Cañon and Hetch Hetchy Valley, while the other swept upward five hundred feet in a broad current across the divide between the basins of the Tuolumne and Merced into the Tenaya basin, and thence down through the Tenaya Cañon and Yosemite Valley.
The maplike distinctness and freshness of this glacial landscape cannot fail to excite the attention of every observer, no matter how little of its scientific significance he may at first recognize. These bald, glossy, westward-leaning rocks in the open middle ground, with their rounded backs and shoulders toward the glacier fountains of the summit mountains and their split angular fronts looking in the opposite direction, every one of them displaying the form of greatest strength with reference to physical structure and glacial action, show the tremendous force with which through unnumbered centuries the ice flood swept over them, and also the direction of the flow; while the mountains, with their sharp summits and abraded sides, indicate the height to which the glacier rose; and the moraines, curving and swaying in beautiful lines, mark the boundaries of the main trunk and