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Show THOUSAND LAKE MOUNTAIN. 281 the first conclusion seems to be that the movement took place after the Laramie beds were deposited and before the Tertiary strata were laid down. The contacts, however, between the Tertiary and Laramie beds have not yet been studied and analyzed, nor have any good exposures of those contacts in this vicinity been discovered. It is not impossible that through a large portion of Cretaceous time this area was a part of an island undergoing a slow erosion, while just beyond the flexure to the eastward the later Cretaceous members were accumulating upon an island coast; that at a later epoch the island was submerged, and received a deposit of Lower Eocene beds. This supposition has considerable support in facts which will be brought forward in the next chapter, and leads to the conclusion that a long interval of disturbance and erosion separated the Cretaceous from the Tertiary throughout this part of the Plateau Province. The absence of more than 5,000 feet of strata between the Lower Eocene and the formation upon which it reposes is a very striking fact, and the simplest explanation is here the best. The Jurassic white sandstone is disclosed all around the mountain. It has the same familiar fades which has been adverted to in the preceding chapters upon the Markagunt and Paunsagunt Plateausâ€"a grayish-white massive sandstone, wonderfully cross-bedded, and weathering into inaccessible domes of peculiarly solid and bold aspect. The upper Jurassic shales appear to be absent, at least they were not detected, and the eroded condition of the sandstone at the time of the deposition of the Tertiary is a sufficient reason for presuming that if the shales once existed here, and I doubt not that they did, they have been swept away. Beneath the Jurassic appear in normal order and relations the Vermilion Cliff sandstones (Upper Trias) and the Shinarump shales. These formations have the same aspect as in the lower terraces which front the Kaibabs in the Grand Canon District. The Vermilion Cliff series has the same succession of sandstones and siliceous shales, usually bright red, but sometimes patched with bright yellowish brown. They are best exposed upon the southern flank of the mountain at the Red Gate. The Shinarump has the same band of conglomerate, consisting of fragments of silicified wood imbedded in white sand, which is seen in the vicinity of the Hurri- |
