Geological Survey Bulletin Volume 1256

Geological Survey Bulletin Volume 1256

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. Excerpt: ...not related to the Continental fault. The folds may be alined with the trace of the buried Wind River thrust fault and, therefore, may have formed as a result of movement of the thrust plate after deposition of the lower and middle Eocene sediments. Some evidence indicates that the second movement of the thrust plate followed the period of normal faulting which produced the Continental fault. The trace of the fault plane is quite sinuous. Some beds on both the downthrown and upthrown blocks dip toward the south and southwest rather than toward the north and northeast. There is a series of small folds in rocks on the downthrown block whose axes closely follow the bends in the trace of the Continental fault. These features can be explained by a southwestward movement of the downthrown northern block producing contortions in the fault plane paralleled by folding in the rocks of the northern block and tilting of the beds on both sides of the fault toward the south and southwest. The buried wedge of Precambrian rocks, too rigid to be deformed, was tilted toward the vertical and the southern end was thus raised to form the Reds Cabin monocline and the Hay syncline. Since the monocline does not cover the entire width of the toe of the thrust, a buried transverse fault may have limited the length of the raised Precambrian segment. GEOLOGIC HISTORY No sedimentary rocks older than the early Eocene are exposed in the map area. For accounts of pre-Eocene history of the general region, reference is made to Wyoming Geological Association (1955). In the local physiographic setting in which Eocene sediments were deposited, the Wind River Range had been elevated, sedimentary rocks stripped off, and the granite core exposed. Arkose and mudstone sediments of the more

Product details

  • Paperback | 24 pages
  • 189 x 246 x 1mm | 64g
  • United States
  • English
  • black & white illustrations
  • 1236755936
  • 9781236755933