Page images

four in width. The concentrated action of this energetic glacier, combined with that of the Tenaya, accomplished the greater portion of the work of the disinterment and sculpture of the great Half Dome, North Dome, and the adjacent rocks. Its fountains, ranged along the southern slopes of the main Hoffmann ridge, gave birth to a series of flat, wing-shaped tributaries, separated from one another by picturesque walls built of massive blocks, bedded and jointed like masonry. The story of its death is not unlike that of the Yosemite Creek, though the declivity of its channel and equal exposure to sun-heat prevented any considerable portion from passing through a torpid condition. It was first burned off on its lower course; then, creeping slowly back, lingered a while at the base of its mountains to finish their sculpture, and encircle them with a zone of moraine soil for gardens and forests.

The gray slopes of Mount Hoffmann are singularly barren in aspect, yet the traveler who is so fortunate as to ascend them will find himself in the very loveliest gardens of the Sierra. The lower banks and slopes of the basin are plushed with chaparral rich in berries and bloom-a favorite resort for bears; while the middle region is planted with the most superb forest of silver-fir I ever beheld. Nowhere are the cold footsteps of ice more warmly covered with light and life.


The rugged, strong-limbed Tenaya Glacier was about twelve miles long, and from half a mile to two and a half miles wide. Its depth varied from near 500 to 2000 feet, according as its current was outspread in many channels or compressed in one. Instead of drawing its supplies directly from the summit fountains, it formed one of the principal outlets of the Tuolumne mer de glace, issuing at once from this noble source, a fullgrown glacier two miles wide and more than a thousand feet deep. It flowed in a general southwesterly direction, entering Yosemite at the head, between Half and North domes. In setting out on its life-work it moved slowly, spending its strength in ascending the Tuolumne divide, and in eroding a series of parallel sub-channels leading over into the broad, shallow basin of Lake Tenaya. Hence, after uniting its main current, which had been partially separated in crossing the divide, and receiving a swift-flowing affluent from the fountains of Cathedral Peak, it set forth again with renewed vigor, pouring its massive floods over the southwestern rim of the basin in a series of splendid cascades; then, crushing heavily against the ridge of Clouds Rest, curved toward the west, quickened its pace, focalized its wavering currents, and bore down upon Yosemite with its whole concentrated energy. Toward the end of the ice-period, and while the upper tributaries of its Hoffmann companion continued to grind rock-meal for coming forests, the whole body of Tenaya became torpid, withering simultaneously from end to end, instead of dying gradually from the foot upward. Its upper portion separated into long parallel strips extending between the Tenaya basin and Tuolumne mer de glace. These, together with the shallow ice-clouds of the lake-basin, melted rapidly, exposing broad areas of rolling rock-waves and glossy pavements, on whose channelless surface water ran everywhere wild and free. There are no very extensive morainal accumulations of any sort in the basin. The largest occur on the divide, near the Big Tuolumne Meadows, and on the sloping ground northwest of Lake Tenaya.* For a distance of six miles from its mouth the pathway of this

a noble glacier is a simple trough from 2000 to 3000 feet deep, countersunk in the solid granite, with sides inclined at angles with the horizon of from thirty to fifty degrees. Above this its grand simplicity is interrupted by huge moutonéed ridges extending in the general direction of its length over into the basin of Lake Tenaya. Passing these, and crossing the bright glacial pavements that border the lake, we find another series of ridges, from 500 to 1200 feet in height, extending over the divide to the ancient Tuolumne ice-fountain. Their bare moutonéed forms and polished surfaces indicate that they were overswept, existing at first as mere boulders beneath the mighty glacier that

* Because the main trunk died almost simultaneously throughout its whole extent, we, of course, find no terminal moraines curved across its channels; nor, since its banks were in most places too steeply inclined for their disposition, do we find much of the two laterals. One of the first Tenaya glacierets was developed in the shadow of Yosemite Half Dome. Others were formed along the bases of Coliseum Peak, and the long, precipitous walls extending from near Lake Tenaya 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 moraine of the main glacier.

flowed in one unbroken current between Cathedral Peak and the southeast shoulder of the Hoffmann range.


The South Lyell Glacier was less influential than the last, but longer and more symmetrical, and the only one of the Merced system whose sources extended directly to the main summits on the axis of the chain. Its numerous ice-wombs, now mostly barren, range side by side in three distinct series at an elevation above sea-level of from 10,000 to 12,000 feet. The first series on the right side of the basin extends from the Matterhorn to Cathedral Peak in a northwesterly direction a distance of about twelve miles. The second series extends in the same direction along the left side of the basin in the summits of the Merced group, and is about six miles in length. The third is about nine miles long, and extends along the head of the basin in a direction at right angles to that of the others, and unites with them at their southeastern extremities. The three ranges of summits in which these fountains are laid, and the long continuous ridge of Clouds Rest, enclose a rectangular basin, leav

a ing an outlet near the southwest corner opposite its principal névé fountains, situated in the dark jagged peaks of the Lyell group. The main central trunk, lavishly fed by these numerous fountains, was from 1000 to 1400 feet in depth, from threefourths of a mile to a mile and a half in width, and about fifteen miles in length. It first flowed in a northwesterly direction for a few miles, then curving toward the left, pursued a westerly course, and poured its shattered cascading currents down into Yosemite between Half Dome and Mount Starr King.

Could we have visited Yosemite toward the close of the glacial period, we should have found its ice-cascades vastly more glorious than their tiny water representatives of the present hour. One of the most sublime of these was formed by that portion of the South Lyell current which descended the broad, rounded shoulder of Half Dome. The whole glacier resembled an oak with a gnarled swelling base and wide-spreading branches. Its banks, a few miles above Yosemite, were adorned with groups of picturesque rocks of every conceivable form and mode of combination, among which glided swift-descending affluents, mottled with black slates from the summits, and gray granite blocks from ridges and headlands. One of the most interesting facts relating to the early history of this glacier is, that the lofty cathedral spur forming the northeast boundary of its basin was broken through and overflowed by deep ice-currents from the Tuolumne region. The scored and polished gaps eroded by them in their passage across the summit of the spur, trend with admirable steadiness in a northeasterly and southwesterly direction; a fact of great importance, considered in its bearings upon questions relating to the universal ice-sheet. Traces of a similar overflow from the northeast occur on the edges of the basins of all the Yosemite glaciers.

The principal moraines of the basin occur in short, irregular sections scattered along the sides of the valleys, or spread in rough beds in level portions of their bottoms, without manifesting subordination to any system whatever. This fragmentary condition is due to interruptions caused by portions of the sides of the valleys being too precipitous for moraine matter to rest upon and to breakings and down-washings of torrents and avalanches of winter snow. The obscurity resulting from these causes is further augmented by forests and underbrush, making a patient study of details indispensable to the recognition of their unity and simple grandeur. The south lateral moraine of the lower portion of the trunk may be traced about five miles, from the mouth of the north tributary of Mount Clark to the cañon of Illilouette, though simplicity of structure has in most places been prevented by the nature of the ground and by the action of a narrow margin glacier which descended against it with variable pressure from cool, shadowy slopes above. The corresponding section of the right lateral, extending from the mouth of Cathedral tributary to Half Dome, is far more perfect in structure, because of the evenness of the ground, and because the ice-wing which curved against Clouds Rest and descended against it was fully exposed to the sun, and was, therefore, melted long before the main trunk, allowing the latter to complete the formation of this section of its moraine undisturbed. Some conception of its size and general character may be obtained by following the Clouds Rest and Yosemite trail, which crosses it obliquely, leading past several cross-sec

[graphic][ocr errors][ocr errors]


« PreviousContinue »