Geologic history of the Yosemite valley (Google eBook)

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U.S. Govt. print. off., 1930 - Geology - 137 pages
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Page 5 - Turner, HW, The Pleistocene geology of the south-central Sierra Nevada, with especial reference to the origin of the Yosemite Valley : Proc.
Page 43 - ... are those stretches that have north-northwesterly or south-southeasterly trends, at right angles to the direction of the tilting, for they have been neither steepened nor flattened by the tilting and still have their original slopes. There are a sufficient number of such stretches to afford a fair conception of the prevailing slopes of the ancient rivers in the northern part of the Sierra Nevada.
Page 49 - A lake 5H miles long occupied a basin gouged into the rock floor of the valley and dammed in addition by a glacial moraine. The vegetation consisted in the main of types now prevailing. The drawing is based primarily on a systematic survey of the moraines and the other glacial features of the valley Echo Peak.
Page 49 - FIGUBE 16.— Bird's-eye view of the Yosemite Valley as It probably was immediately after the ice age. The valley had been broadened and deepened to essentially its present proportions. The deepening accomplished by the ice ranged from 600 feet at the lower end to 1,500 feet at the upper end. A third set of hanging valleys had been added, and the Brldalveil Fall was produced.
Page 4 - Muir,6 the keen student and ardent lover of nature, who first saw clearly that the glaciers themselves had done most of the excavating.
Page 121 - The great bulk of the granitic rocks in the Yosemite region belong to two series of intrusions, the members of each series exhibiting an especially close relationship to one another. These may be termed the biotite granite series of the Yosemite Valley and the Tuolumne intrusive series. The former includes the El Capitan and Taft granites and several minor intrusive masses confined mostly to the lower and middle parts of the valley; the latter includes the Sentinel granodiorite, Half Dome quartz...
Page 8 - ... be taken into account in any discussion of the Yosemite 's mode of origin. THE SIERRA NEVADA GENERAL CHARACTER AND DIMENSIONS The Sierra Nevada is a single unbroken mountain range, yet it is comparable in magnitude to an entire mountain system. As is manifest from the relief map » Bunnell, LH, Discovery of the Yosemite, and the Indian War of 1851, 4th ed . ' Los Angeles, 1911. 8 GEOGRAPHIC SKETCH OF THE YOSEMITE REGION AND THE SIERRA NEVADA 9 (pi.
Page 28 - The geologic epochs when these different oscillations took place are indicated by the fossil shells and other remains contained in the deposits. Similar testimony is afforded by the layers of rock waste that have accumulated in the basins east of the Sierra Nevada and in the Mohave Desert, to the south. Much has been learned also from the "fossil river beds" that occur in the north half of the range — river beds that were entombed by flows of lava and that were partly brought to light again later...
Page 115 - FIGURE 38. — Diagram showing how, by progressive exfoliation, the angularities of a rock mass are replaced by smooth curves they are among the oldest features of its landscape. Their sweeping curves attest their great antiquity. Domes such as Sentinel Dome and Mount Starr King, which stand above the general level of the Yosemite upland, doubtless were in process of exfoliation as far back as the Miocene epoch, at least 8,000,000...
Page 86 - Quantity of rock removed by the to estimated at 1,700,000 cubic yards. AA, Preglacial profile; BB, approximate bottom curve of the glacial U trough; CC, present profile yon of preglacial time has been transformed into the broad U trough of to-day. It is evident, further, from the very breadth of the U profile that the glacial processes far outstripped the fluvial processes, for whatever trenching the river did in interglacial epochs must have tended to produce an inner gorge, yet of such a gorge...

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