| OCR Text |
Show 165 In the Rifle Creek area the sedimentary formations strike east-west and dip 20° to 25° to the south. In the vicinity of the vanadium mine a hogback facing north is formed in the upper part of the "Red Beds," which are of Permo-Triassic age, the Entrada sandstone and Morrison formation of Jurassic age, and the Dakota sandstone. The Mancos shale stratigraphically above the Dakota is exposed to the south on the lower back slope of the hogback. To the north the "Red Beds" are exposed over a wide area of hills and valleys and still farther north and higher on the flanks of the White River Plateau are the Pennsylvanian and .earlier Paleozoic formations. The "Red Beds," also called the "Dolores formation" in some reports, are interbedded red sandstone and shale 2,000 to 3,000 feet thick in the surrounding area. The lower part of the formation has been generally regarded as of Permian age and the upper part possibly of Triassic age. The boundary between the Permian and Triassic rocks has never been, established with any certainty and therefore the name "Permo-Triassic" is used. The top of the "Red Beds" is marked by the Entrada sandstone, a white to light-gray formation about 120 feet thick. The light-colored cliffs of Entrada sandstone stand out in sharp contrast to the underlying exposures of red sandstone and shale, The lower 20 to 30 feet of the |
