Page:Popular Science Monthly Volume 85.djvu/78

74 indications of such complex Assuring and faulting, but reasoned in rebuttal, that pressure from the mile high rock-masses above had so united yielding materials, subsequently transported by erosion, that all the traces of fracture had been lost.

Professor Whitney was most positive in his idea that denudation had but little affected the formation of the walls of the valley or its domes. Had there been a considerable amount of erosion, its evidence would have been piled up in masses of debris along the course of the Merced River. "No ordinary denudation moulded the domes," he declared. Instead, he insisted that the Sierran domes of granite were fashioned in a series of concentric layers while the igneous rocks were cooling.

Associated with Professor Whitney was young Clarence King, who later won fame as the chief of the United States Geological Survey. King was the first to trace the courses of glaciers down into the Yosemite Valley. He called attention to the beautifully-polished surfaces gleaming above the floor of the valley and pointed out four distinct moraines, one between Half Dome and Washington Column, a medial moraine between Tenaya Creek and the Merced River, a third, lingering in the gorge of the latter stream above the Happy Isles, while a fourth forms an imposing barrier below the narrows where the Cathedral Rocks approach El Capitan. Clarence King did not claim that ice filled the Yosemite Valley, but he declared its maximum depth to have been about 1,000 feet.

When John Muir first explored the Sierras, some forty-five years ago, he became imbued with the belief that the carving of the Yosemite had been effected almost entirely by ice. His earliest contributions to the literature of science and of the Sierras was a series of papers in which he endeavored to show how a vast sheet of ice, forty or fifty miles in width, cut across the crest of the range, quarrying for thousands of feet down through more friable formations; or enveloping and sweeping over the harder masses of granite, leaving striated and polished domes in the wake of the congealed flood. Muir attached great significance to the "hanging valleys," cut off abruptly by precipices, two and three thousand feet sheer. To this glacialist, their only logical explanation was that a great plow of ice, shod with sharp abrasives, had furrowed the main valley below to untold depth. All the wealth of scenic wonders for which the Yosemite region is so famous, he contended had been chiseled by grinding glaciers. Tracing the tributaries of the San Joaquin, Merced and Tuolumne Rivers to their fountains of perpetual snow, he discovered, during the seventies, no less than sixty-five surviving glaciers still busy at their lapidary labors.

Professor Whitney at first credited the discoveries of Clarence King, referring in his report of 1865 to the fact that "King and Gardner obtained ample evidence of the former existence of a glacier in the Yosemite Valley." But, five years later he reversed his decision, declaring,