File:Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean (1855) (14573816607).jpg

Identifier: reportsofexplora05unit_0 (find matches)
Title: Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean
Year: 1855 (1850s)
Authors: United States. War Dept Henry, Joseph, 1797-1878 Baird, Spencer Fullerton, 1823-1887 United States. Army. Corps of Engineers
Subjects: Pacific railroads Discoveries in geography Natural history Indians of North America
Publisher: Washington : A.O.P. Nicholson, printer (etc.)
Contributing Library: San Francisco Public Library
Digitizing Sponsor: California State Library Califa/LSTA Grant

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wenty-five miles. Thesemeasurements are approximate, and give for the whole area, west of the Colorado, about 8,250square miles, or, including a portion of the plain beyond the river, about 9,000 square miles.A similar Desert borders the Colorado River on the east side, and appears to extend for a longdistance up the Gila, and to reach to the foot of a range of mountains in Sonora, but, as theexploration did not extend so far as to ascertain the boundaries, it is not included in the descrip-tion. The coloring on the map is, however, extended so as to indicate the geological characterof that part of the region near the river. The exact parallelism of the valley of the Desert with the coast, and with an intermediateline, formed by a succession of the narrow valleys of Vallecito, San Felipe, Warners, and theSan Luis River, and also with the Bernardino Pass, is worthy of notice. It is strikinglyexhibited by the distribution of the colors of the map. They clearly mark out the direction and
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SURFACE OF THE COLORADO DESERT. 229 prevailing trend of the granitic elevations to which the region owes its configuration. A pre-dominant northwest and southeast trend of the principal lines of elevation is said to characterizethe mountain ranges along the Gila Eiver.1 It is also visible, in detail, in the range on thenorth of the Desert, where the ridges project in a series of overlapping points, forming long andre-entering angles. This appears to result from a series of parallel ridges succeeding each otherfrom west to east, and overlapping towards the southeast. This composite character will hefound in nearly all of the mountain ranges of California; hut, so far as my observations haveextended, this is the only instance where the overlapping of the ridges is towards the southeast;it is generally the reverse, or towards the northeast. ASPECT OF THE SURFACE OF THE DESERT. Before I reached the surface of the Desert I had been accustomed to regard it as a vast plainof gravel and sand,

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