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Show 290 GEOLOGY OF THE HIGH PLATEAUS. domes and crags of the Water Pocket fold, huge promontories of red and white massive sandstone, separated by narrow clefts, many of which are cut down to the level of the plain and even lower, so that they carry a portion of the drainage from within the "Circle Cliffs" to the Water Pocket Canon. On the west side of the plain the mesa which looks down upon it is slashed by many narrow and profound canons, which wind about within it and open into the canon of the Escalante. These carry the remaining drainage of the plainâ€"i. e., when there is any to carry, which I warrant is seldom enough. The floor of this cliff-bound area is Lower Trias (Shina-rump), and the walls which inclose it upon the west are Yermilion Cliff Trias, and those upon the east are the same, with the Jurassic sandstone a little beyond them. The plain is barren, treeless, and waterless, so far as known. It constitutes one of the centers of erosion of this part of the Plateau Country, from which the waste of the strata edgewise has proceeded radially outwards. Probably the Cretaceous was eroded from its surface prior to the Eocene, and the Tertiary afterwards deposited upon the Jura in the same relation as is now seen high up on the flanks of the Aquarius. The late erosion has removed the Eocene, the Jura, and the Upper Trias. Far to the southeastward, upon the horizon, rises a gigantic dome of wonderfully symmetric and simple form. It is the Navajo Mountain. Conceive a segment of a sphere cut off by a plane through the 70th parallel of latitude, and you have its form exactly. From whatsoever quarter it is viewed, it always presents the same profile. It is quite solitary, without even a foot-hill for society, and its very loneliness is impressive. It stands upon the southern brink of the Glen Canon of the Colorado, at the junction of the San Juan River. Its structure is believed by Mr. G. K. Gilbert to be laccolitic. Its summit has not yet been reached by any exploring party, and the approaches to it from all sides are extremely difficult.* On the north side runs the profound chasm of the Colorado, on the east the canon of the San Juan, and on the west another side gorge. South of * Professor Powell, during his descent of the Colorado River, climbed out of the canon and ascended about half-way to the summit. He believed that if time had permitted he could have gained the top of the mountain. |
