Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 Excerpt: ... Mountains and Big Sandy Wash consists of a long, graded detrital slope (see fig. 2, p. 24), more or less deeply cut by parallel washes, such as Deluge Wash. This highly inclined detrital slope, the western fault scarp of the Hualpai Mountains, and the fault scarp to the east (Aquarius Cliffs) all terminate at the south in practically the same latitude. The southern end of the valley, between the Artillery Mountains and the Aubrey Hills, has a slight inclination to the east, but is in general an undissected and undrained detrital plain. Rock formations.--The oldest rocks in the Big Sandy Valley are the granites exposed in the bordering mountains and cliffs, which, because of their resemblance to the granite beneath the Cambrian sediments in the Grand Wash Cliffs, are thought to be of pre-Cambrian age. They are overlain in places by Tertiary andesites. The trough formed by these older rocks is partly filled with rock debris which has been later exposed by erosion. The oldest detrital beds have been upturned and eroded to depths of 800 feet or more. They are composed of clay, sand, and gravel, and in places contain Fig. 14.--Sketch section across Big Sandy Wash near mouth of Deluge Wash, showing the older gravels tilted eastward, eroded, and overlain by younger gravels, and again eroded and partly covered by recent flood-plain deposits. 1, Flood-plain deposits; 2, Temple Bar (?) conglomerate; 3, gravel. granite bowlders 5 to 8 feet in diameter. In other places, as at Deluge Wash (Pl. IV, B), they are composed of clay and fine, wellstratified sand and volcanic ash. Within the valley eroded in the oldest tilted detrital beds, and resting with horizontal bedding upon their eroded edges, is a second series of gravel deposits. These are perhaps best exposed near t...
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