File:Forest physiography; physiography of the United States and principles of soils in relation to forestry (1911) (14796743303).jpg

Identifier: forestphysiograp01bowm (find matches)
Title: Forest physiography; physiography of the United States and principles of soils in relation to forestry
Year: 1911 (1910s)
Authors: Bowman, Isaiah, 1878-1950
Subjects: Physical geography Forests and forestry Soils
Publisher: New York, J. Wiley & sons (etc., etc.)
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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and intervening basins is north-south, except near and south ofthe New Mexico-Texas boundary where they trend northwest-southeast.In general the elevations are distinctly lower than those of any otherportion of the Pacific Cordillera in this longitude. Only two peaks riseabove 8000 feet and the general elevation of the lowlands is from 3500to 4500 feet. While the greater number of the Trans-Pecos mountains have a fault-block origin, as a whole they are of diverse origin, structure, and topog-raphy. They exhibit many irregular forms of relief and all have sharpand rugged outlines. Few of them rise to the height of the dry timberline (6000 feet). On the summits and in the higher canyons of theSacramento, Chisos, and Davis mountains, and a few others, this ele-vation is exceeded and a certain amount of timber is found. On thelower and drier mountains the vegetation consists of edible pines, avariety of junipers, and several species of maguey. The lower eleva- 387 S88 FOREST PHYSIOGRAPHY
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0 25 50 Fig. 133. — Principal mountain ranges of the Trans-Pecos province, chief drainage features, and thebordering Llano Estacado on the east. (U. S. Geol. Surv.) TRANS-^PECOS HIGHLANDS 389 tion of the group as a whole is expressed in the lesser rainfall andgeneral barrenness of the mountains in contrast to the partly timberedRocky Mountains to the north. The highest summit is Sierra Blanca(ii,SSo feet) in the Sacramento range in southern New Mexico, but ingeneral the peaks fall short of this altitude. Mountain Types Four types of mountains may be identified: (i) mountains of deforma-tion, consisting of structural folds or tilted fault blocks in which theoutline of the mountain is in sympathy with the structural breaks or

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