I had long been anxious to study some points in the structure of the ice-hill at the foot of the Upper Yosemite Fall, but, as I have already explained, blinding spray had hitherto prevented me from getting sufficiently near it. This morning the entire body of the Fall was oftentimes torn into gauzy strips and blown horizontally along the face of the cliff, leaving the ice-hill dry; and while making my way to the top of Fern Ledge to seize so favorable an opportunity to look down its throat, the peaks of the Merced group came in sight over the shoulder of the South Dome, each waving a white glowing banner against the dark blue sky, as regular in form and firm and fine in texture as if it were made of silk. So rare and splendid a picture, of course, smothered everything else and I at once began to scramble and wallow up the snow-choked Indian CaΓ±on to a ridge about 8000 feet high, commanding a general view of the main summits along the axis of the Range, feeling assured I should find them bannered still more gloriously; nor was I in the least disappointed. I reached the top of the ridge in four or five hours, and through an opening in the woods the most imposing wind-storm effect I ever beheld came full in sight; unnumbered mountains rising sharply into the cloudless sky, their bases solid white their sides plashed with snow, like ocean rocks with foam, and on every summit a magnificent silvery banner, from two thousand to six thousand feet in length, slender at the point of attachment, and widening gradually until about a thousand or fifteen hundred feet in breadth, and as shapely and as substantial looking in texture as the banners of the finest silk, all streaming and waving free and clear in the sun-glow with nothing to blur the sublime picture they made.
Fancy yourself standing beside me on this Yosemite Ridge. There is a strange garish glitter in the air and the gale drives wildly overhead, but you feel nothing of its violence, for you are looking out through a sheltered opening in the woods, as through a window. In the immediate foreground there is a forest of silver fir their foliage warm yellow-green, and the snow beneath them strewn with their plumes, plucked off by the storm; and beyond broad, ridgy, caΓ±on-furrowed, dome-dotted middle ground, darkened here and there with belts of pines, you behold the lofty snow laden mountains in glorious array, waving their banners with jubilant enthusiasm as if shouting aloud for joy. They are twenty miles away, but you would not wish them nearer, for every feature is distinct and the whole wonderful show is seen in its right proportions, like a painting on the sky.
And now after this general view, mark how sharply the ribs and buttresses and summits of the mountains are defined, excepting the portions veiled by the banners; how gracefully and nobly the banners are waving in accord with the throbbing of the wind flood; how trimly each is attached to the very summit of its peak like a streamer at a mast-head; how bright and glowing white they are, and how finely their fading fringes are penciled on the sky! See how solid white and opaque they are at the point of attachment and how filmy and translucent toward the end, so that the parts of the peaks past which they are streaming look dim as if seen through a veil of ground glass. And see how some of the longest of the banners on the highest peaks are streaming perfectly free from peak to peak across intervening notches or passes, while others overlap and partly hide one another.
As to their formation, we find that the main causes of the wondrous beauty and perfection of those we are looking at are the favorable direction and force of the wind, the abundance of snow-dust, and the form of the north sides of the peaks. In general, the north sides are concave in both their horizontal and vertical sections, having been sculptured into this shape by the residual glaciers that lingered in the protecting northern shadows, while the sun-beaten south sides, having never been subjected to this kind of glaciation, are convex or irregular. It is essential, therefore, not only that the wind should move with great velocity and steadiness to supply a sufficiently copious and continuous stream of snow-dust, but that it should come from the north. No perfect banner is ever hung on the Sierra peaks by the south wind. Had the gale today blown from the south, leaving the other conditions unchanged, only swirling, interfering, cloudy drifts would have been produced; for the snow, instead of being spouted straight up and over the tops of the peaks in condensed currents to be drawn out as streamers, would have been driven over the convex southern slopes from peak to peak like white pearly fog.
It appears, therefore, that shadows in great part determine not only the forms of lofty ice mountains, but also those of the snow banners that the wild winds hang upon them.
The avalanche taluses, leaning against the walls at intervals of a mile or two, are among the most striking and interesting of the secondary features of the Valley. They are from about three to five hundred feet high, made up of huge, angular, well-preserved, unshifting boulders, and instead of being slowly weathered from the cliffs like ordinary taluses, they were all formed suddenly and simultaneously by a great earthquake that occurred at least three centuries ago. And though thus hurled into existence in a few seconds or minutes, they are the least changeable of all the Sierra soil-beds. Excepting those which were launched directly into the channels of swift rivers, scarcely one of their wedged and interlacing boulders has moved since the day of their creation; and though mostly made up of huge blocks of granite, many of them from ten to fifty feet cube, weighing thousands of tons with only a few small chips, trees and shrubs make out to live and thrive on them and even delicate herbaceous plantsβdraperia, collomia, zauschneria, etc., soothing and coloring their wild rugged slopes with gardens and groves.
I was long in doubt on some points concerning the origin of those taluses. Plainly enough they were derived from the cliffs above them, because they are of the size of scars on the wall, the rough angular surface of which contrasts with the rounded, glaciated, unfractured parts. It was plain, too, that instead of being made up of material slowly and gradually weathered from the cliffs like ordinary taluses, almost every one of them had been formed suddenly in a single avalanche, and had not been increased in size during the last three or four centuries, for trees three or four hundred years old are growing on them, some standing at the top close to the wall without a bruise or broken branch, showing that scarcely a single boulder had ever fallen among them. Furthermore, all these taluses throughout the Range seemed by the trees and lichens growing on them to be of the same age. All the phenomena thus pointed straight to a grand ancient earthquake. But for years I left the question open, and went on from caΓ±on to caΓ±on, observing again and again; measuring the heights of taluses throughout the Range on both flanks, and the variations in the angles of their surface slopes; studying the way their boulders had been assorted and related and brought to rest, and their correspondence in size with the cleavage joints of the cliffs from whence they were derived, cautious about making up my mind. But at last all doubt as to their formation vanished.
At half-past two oβclock of a moonlit morning in March, I was awakened by a tremendous earthquake, and though I had never before enjoyed a storm of this sort, the strange thrilling motion could not be mistaken, and I ran out of my cabin, both glad and frightened, shouting, βA noble earthquake! A noble earthquake!β feeling sure I was going to learn something. The shocks were so violent and varied, and succeeded one another so closely, that I had to balance myself carefully in walking as if on the deck of a ship among waves, and it seemed impossible that the high cliffs of the Valley could escape being shattered. In particular, I feared that the sheer-fronted Sentinel Rock, towering above my cabin, would be shaken down, and I took shelter back of a large yellow pine, hoping that it might protect me from at least the smaller outbounding boulders. For a minute or two the shocks became more and more violentβflashing horizontal thrusts mixed with a few twists and battering, explosive, upheaving jolts,βas if Nature were wrecking her Yosemite temple, and getting ready to build a still better one.