The Yosemite

by John Muir

I should like now to offer some nearer views of a few characteristic specimens of these wonderful old ice-streams, though it is not easy to make a selection from so vast a system intimately inter-blended. The main branches of the Merced Glacier are, perhaps, best suited to our purpose, because their basins, full of telling inscriptions, are the ones most attractive and accessible to the Yosemite visitors who like to look beyond the valley walls. They number five, and may well be called Yosemite glaciers, since they were the agents Nature used in developing and fashioning the grand Valley. The names I have given them are, beginning with the northern-most, Yosemite Creek, Hoffman, Tenaya, South Lyell, and Illilouette Glaciers. These all converged in admirable poise around from northeast to southeast, welded themselves together into the main Yosemite Glacier, which, grinding gradually deeper, swept down through the Valley, receiving small tributaries on its way from the Indian, Sentinel, and Pohono Cañons; and at length flowed out of the Valley, and on down the Range in a general westerly direction. At the time that the tributaries mentioned above were well defined as to their boundaries, the upper portion of the valley walls, and the highest rocks about them, such as the Domes, the uppermost of the Three Brothers and the Sentinel, rose above the surface of the ice. But during the Valley’s earlier history, all its rocks, however lofty, were buried beneath a continuous sheet, which swept on above and about them like the wind, the upper portion of the current flowing steadily, while the lower portion went mazing and swedging down in the crooked and dome-blocked cañons toward the head of the Valley.

Every glacier of the Sierra fluctuated in width and depth and length, and consequently in degree of individuality, down to the latest glacial days. It must, therefore, be borne in mind that the following description of the Yosemite glaciers applies only to their separate condition, and to that phase of their separate condition that they presented toward the close of the glacial period after most of their work was finished, and all the more telling features of the Valley and the adjacent region were brought into relief.

The comparatively level, many-fountained Yosemite Creek Glacier was about fourteen miles in length by four or five in width, and from five hundred to a thousand feet deep. Its principal tributaries, drawing their sources from the northern spurs of the Hoffman Range, at first pursued a westerly course; then, uniting with each other, and a series of short affluents from the western rim of the basin, the trunk thus formed swept around to the southward in a magnificent curve, and poured its ice over the north wall of Yosemite in cascades about two miles wide. This broad and comparatively shallow glacier formed a sort of crawling, wrinkled ice-cloud, that gradually became more regular in shape and river-like as it grew older. Encircling peaks began to overshadow its highest fountains, rock islets rose here and there amid its ebbing currents, and its picturesque banks, adorned with domes and round-backed ridges, extended in massive grandeur down to the brink of the Yosemite walls.

In the meantime the chief Hoffman tributaries, slowly receding to the shelter of the shadows covering their fountains, continued to live and work independently, spreading soil, deepening lake-basins and giving finishing touches to the sculpture in general. At length these also vanished, and the whole basin is now full of light. Forests flourish luxuriantly upon its ample moraines, lakes and meadows shine and bloom amid its polished domes, and a thousand gardens adorn the banks of its streams.

It is to the great width and even slope of the Yosemite Creek Glacier that we owe the unrivaled height and sheerness of the Yosemite Falls. For had the positions of the ice-fountains and the structure of the rocks been such as to cause down-thrusting concentration of the Glacier as it approached the Valley, then, instead of a high vertical fall we should have had a long slanting cascade, which after all would perhaps have been as beautiful and interesting, if we only had a mind to see it so.

The short, comparatively swift-flowing Hoffman Glacier, whose fountains extend along the south slopes of the Hoffman Range, offered a striking contrast to the one just described. The erosive energy of the latter was diffused over a wide field of sunken, boulder-like domes and ridges. The Hoffman Glacier, on the contrary moved right ahead on a comparatively even surface, making descent of nearly five thousand feet in five miles, steadily contracting and deepening its current, and finally united with the Tenaya Glacier as one of its most influential tributaries in the development and sculpture of the great Half Dome, North Dome and the rocks adjacent to them about the head of the Valley.

The story of its death is not unlike that of its companion already described, though the declivity of its channel, and its uniform exposure to sun-heat prevented any considerable portion of its current from becoming torpid, lingering only well up on the Mountain slopes to finish their sculpture and encircle them with a zone of moraine soil for forests and gardens. Nowhere in all this wonderful region will you find more beautiful trees and shrubs and flowers covering the traces of ice.

The rugged Tenaya Glacier wildly crevassed here and there above the ridges it had to cross, instead of drawing its sources direct from the summit of the Range, formed, as we have seen, one of the outlets of the great Tuolumne Glacier, issuing from this noble fountain like a river from a lake, two miles wide, about fourteen miles long, and from 1500 to 2000 feet deep.

In leaving the Tuolumne region it crossed over the divide, as mentioned above, between the Tuolumne and Tenaya basins, making an ascent of five hundred feet. Hence, after contracting its wide current and receiving a strong affluent from the fountains about Cathedral Peak, it poured its massive flood over the northeastern rim of its basin in splendid cascades. Then, crushing heavily against the Clouds’ Rest Ridge, it bore down upon the Yosemite domes with concentrated energy.

Toward the end of the ice period, while its Hoffman companion continued to grind rock-meal for coming plants, the main trunk became torpid, and vanished, exposing wide areas of rolling rock-waves and glistening pavements, on whose channelless surface water ran wild and free. And because the trunk vanished almost simultaneously throughout its whole extent, no terminal moraines are found in its cañon channel; nor, since its walls are, in most places, too steeply inclined to admit of the deposition of moraine matter, do we find much of the two main laterals. The lowest of its residual glaciers lingered beneath the shadow of the Yosemite Half Dome; others along the base of Coliseum Peak above Lake Tenaya and along the precipitous wall extending from the lake to the Big Tuolumne Meadows. The latter, on account of the uniformity and continuity of their protecting shadows, formed moraines of considerable length and regularity that are liable to be mistaken for portions of the left lateral of the Tuolumne tributary glacier.