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Show 44 GEOLOGY OF THE HIGH PLATEAUS. Plateaus are they brought to light; but around the southeastern borders of the district they are displayed conspicuously. The age of these flexures is apparently Post-Cretaceous and Pre-Tertiary; that is, they occupy, in respect to time, an interval which separates the Mesozoic from the Tertiary.* They consist of a series of monoclinal flexures, quite perfect in form, which trend from northwest to north-northwest. They involve the Mesozoic beds, but not the Tertiary. They come up from the southeast, and disappear under the Aquarius Plateau, and on the southern and southeastern flanks are laid bare by a vast erosion. Just before they reach this plateau they are seen to be eroded, and near the summit the Eocene beds are seen to lie unconform-ably across the beveled edges, and still farther on near the lava cap they rest upon the Jurassic. All around the southern and eastern flanks of the Aquarius and along a part of the northern flank, also entirely around the circumference of Thousand Lake Mountain (with the possible exception of its northern end), the contact of the Tertiary with the Jurassic is obvious. Farther eastward in the heart of the Plateau Province, outside of the district of the High Plateaus, are three more displacements of grand proportions, of which I can make but a passing mention. The southernmost is the Echo Cliff flexure, a great monoclinal seen south of the Colorado near the Moquis towns. Trending a little west of north, it crosses the river at the head of Marble Canon, and continuing along the Paria River dies out near Paria settlement at the base of the Vermilion Cliffs. Partner east is the Water-Pocket flexure, one of the grandest monoclinals of the West. It crosses the Colorado in the heart of Glen Carton, and running north-northwest between the Henry Mountains and Aquarius for nearly 60 miles, swings around to the west in a great curve and disappears under Thousand Lake Mountain. The third is the San Rafael flexure, beginning as a branch of the Water-Pocket flexure, where the latter changes its trend, and running north-northeast along the eastern side of the San Rafael swell, passes off into the northeast and dies out again. These are all monoclinal flexures of imposing dimensions and of perfect form. Their age I cannot speak of at present in any detail, though it is hardly doubtful that they go far back in Tertiary *Here, as elsewhere in this work, the Laramie beds are reckoned with the Cretaceous, of Avhich they form the upper group of beds. |