Page:Popular Science Monthly Volume 85.djvu/73

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THE marvelous structure and sculpture of the Yosemite Valley kindles the imagination of every visitor to this great natural wonder and causes scientist and layman alike to evince the most intense interest in the origin of this mile-deep trough amid the granite waves of the High Sierra. Each pilgrim to this Mountain-Mecca endeavors to satisfy his mind as to the causes of its carving. Every one who wanders there wonders and guesses at its genesis; but the revelations of its geomorphogeny are far from being satisfactory or complete. Scientists have come and savants have gone, but few have agreed in their conclusions. The scenic grandeur of the Yosemite has sunk deep in the souls of poets and painters, artists and literateurs; and to the most practical of men, engineers and miners, do its unique features equally appeal. Awe-inspiring evidences of colossal dynamic agencies, such as the undermining and subsidence of vast areas, or the tremendous upheaval of sky-piercing peaks and ridges, the quarrying and ground sluicing of Brobdignagian blocks of granite, are all of deep significance and extreme interest to the mind of the miner. Over all this weird wonderland broods the spell of an enigmatic Sphinx. To this day, the Yosemite is, of a verity, the Valley of Mystery.

General Geological Features

Before discussing the conflicting theories conjectured about the origin of the Yosemite Valley, it will be proper to present the salient features of its surroundings. Trite, but essential to clearer understanding, is the statement that the valley is approximately eight miles long and nearly a mile in extreme width and depth. Its floor averages 3,960 feet above sea level. At first glance, it will impress the miner as being a great open cut quarried through blocks of more or less resistant granite. And to many it will appear to be a great basin, the bottom of which had sunk to unfathomed depths. Whatever forces may have quarried this great open cut—if open cut it may be truly called—the accumulation of the tailings down stream from this titanic denudation is conspicuous by its absence. Therefore, the secret of the transportation of these billions of tons of tailings is one of the mysteries of the geological history of the Yosemite yet to be unfolded.

Looking up the valley from its lower portal, two striking differences in the structure of its walls are seen in bold contrast to each other.