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Show 148. GEOLOGY OF THE HIGH PLATEAUS. impregnating the sandstones and shales in sufficient quantity to attract both miners and capital to the locality. The Shinarump has but a few exposures within the District of the High Plateaus. The best example is seen at the Red Gate, at the foot of Rabbit Valley, where the Fremont River passes out into the desert waste in the heart of the Plateau Province. A belt of this formation is seen near the summit of the Water-Pocket flexure, flanking the northeastern part of the Aquarius a few miles from its base. It is brought up to daylight southwest of the Markagunt by the Hurricane fault, and the beds are there sharply * flexed in the vicinity of the fault-plane, but quickly smooth out to the eastward and southward. The principal area of the Shinarump is south of the Vermilion Cliffs, in the northern part of the Kaibab District, around the junction of the Grand and Green and in the San Rafael Swell. Generally speaking, it is usually found as the first terrace above the Carboniferous in the areas of maximum erosion. THE TEIAS. Next above the Shinarump shales is found an extensive series of sandstones constituting the Trias. Probably no formation in Southern Utah is better exposed, but notwithstanding this, it has not in this part of the Plateau Province hitherto yielded a solitary fossil of any kind. Still we are not in doubt about the correlative age of the group for its continuity with beds found by Newberry in New Mexico, and yielding a distinctly Triassic flora; its further continuity and identity with Red-beds in the Uintas having a Jurassic fauna above and the unmistakable Shinarump shales below; and, lastly, its identity with the beds of Idaho, which furnished Dr. Peale a well-marked Triassic fauna, are sufficiently certain. The contact with the shales below is usually conformable, but in the vicinity of the Hurricane fault, where the whole Triassic series is displayed, the junction is often unconformable. The separation, however, of the Trias into an upper and lower series, so far as Southern Utah is concerned, is based upon lithological grounds chiefly. It is also a matter of great convenience to effect this separation., since each division has its own topography, and their distributions differ notably. There is, also, a decided con- |
