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Title: The Tertiary Gravels of the Sierra Nevada of California by Waldemar Lindgren (1911) Collection Type: Books and Periodicals Source(s): Google Books # of Pages: 301 Download PDF: User Login Required Download OCR Text: User Login Required

Date Scanned: 2024-07-14 06:26:22 Item Sourced From: PDF First Created: 2025-03-17 05:53:20 Last Updated: 2025-03-17 05:53:20

Original Held At: Searls Historical Library Location: 161 Nevada City Hwy, Nevada City, CA 95959

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48 TERTIARY GRAVELS OF THE SIERRA NEVADA OF CALIFORNIA. Piute Creek and it probably headed near Mount Dana. In this upper course the grades are about 130 feet to the mile. In the profile of the present river we note the same combination of two concave curves, the influence of glaciation being felt as far as Hetch Hetchy Valley. The last four profiles, of the southern rivers, are thoroughly consistent and indicate uniform tilting of well-graded rivers without perceptible deformation. VIEWS OF KING, LE CONTE, AND RUSSELL. It is interesting to note that three eminent geologists—King, Le Conte, and Russell—who well knew the Sierra Nevada and the Great Basin, arrived at the same conclusion—that the uplift involved both regions and that the faults were accompanied by downthrows on the east side. King,' after discussing the folding and subsequent faulting of the Great Basin, says: The result of this complicated interlacing system of dislocation is that all ranges of the Great Basin have been broken into irregular blocks, sections of which have sunk many thousand feet below the level of the adjoining members. * * * The two grandest fault lines shown in the Great Basin are those which define its east and west walls. Whoever has followed the eastern slope of the Sierra from the region of Honey Lake to Owens Valley can not have failed to observe with wonder the 300 miles of abrupt wall which the Sierra Nevada turns to the east. That wall is no other but a great continuous fault by which the Nevada country has been dropped from 3,000 to 10,000 feet downward. In this low trough, east of the Sierra Nevada and Cascade Range, is laid down the thick series (amounting to 4,000 feet as already described) of Miocene beds. It is therefore evident that this was a depression which was defined before the beginning of Miocene times. * * * As yet in the depressed area east of the Sierra Nevada no Eocene beds have been discovered, from which it seems highly probable that the great fault occurred either within the Eocene or at the close of Eocene time and was the direct cause of the subsidence whose area was immediately occupied by the Miocene Pahute Lake. These views are similar to those expressed later by Le Conte? in a paper on the origin of normal faults. He writes: The whole region from the Wasatch to the Sierra, inclusive, was lifted by intumescent lava into a great arch, the abutments of which were the Sierra on the one side and the Wasatch on the other. * * * The arch broke down and the broken parts readjusted themselves by gravity into the ridges and valleys of the basin region, leaving the abutments overlooking the basin and toward one another. Russell * was the first to recognize the compound character of the great fault system. He says: On the west side of the Great Basin, at the immediate base of the Sierra Nevada, there isan immense compound displacement that can be followed all the way from Honey Lake on the north to beyond Owens Lake on the south, a distance of over 350 miles. Among many of the faults composing this belt the records of a post-Quaternary movement may be clearly recognized. Fault scarps produced by the recent movements have been observed in Eagle and Caron valleys, south of Carson City, in Bridgeport Valley, and on the west side of Mono Lake. The earthquake in Owens Valley in 1872 was caused by a movement along one of the faults of this series. In a later paper * Russell describes a recent scarp at Mono Lake and makes some pertinent observations as to the character of the dislocation, substantially as follows: A fault scarp having a throw of 50 feet crosses the moraines and the delta deposits at the mouth of Lundy Canyon. The beach lines are deformed. The difference in elevation of the beach line on opposite sides of the displacement, as indicated by the measurements, is less than the height of the recent fault scarp and shows that the greatest movement has been in close proximity to the line of faulting. The simplest hypothesis which seems to explain the facts observed is that a recent movement has taken place along the fault which has resulted in a displacement of at least 50 feet. That the displacement was caused or at least accompanied by a subsidence of the block forming the thrown side of the fault is indicated by the present position of Lake Mono. Assuming that the basin had been undisturbed since its occupation by the ancient lake, it is evident that sedimentation would have been greatest along the southwestern border, where the creeks from the mountains empty into it, and that this portion of the depression would have been filled much more rapidly than the northern border, where there are no tributaries. The present lake, under these conditions, should have been somewhat removed from the mountains, as it would have been crowded northward by progressive sedimentation. We find, on the con1 King, Clarence, U. S. Geol. Expl. 40th Par., vol. 1, Systematic geology, 1878, pp. 742-744. 2 Le Conte, Joseph, Am. Jour. Scl., 3d ser., vol. 38, 1889, p. 262. 3 Russell, 1. C., Notes on the faults of the Great Basin and of the eastern base of the Sierra Nevada: Bull. Philos. Soc. Washington, vol. 2%, 1887, pp. 5-7. 4 Quaternary history of Mono County, California: Eighth Ann. Rept. U. S. Geol. Survey, pt. 1, 1889, pp. 302-304.