Forest physiography; physiography of the United States and principles of soils in relation to forestry . ordwith the present slope of the plateau surface (p. 284) is that of the 1 F. V. Hayden, U. S. Geog. and Geol. Surv. of the Terr., 1875, pp. 340, 341, 349. 2 Henry Gannett, U. S. Geol. and Geog. Surv. of Col. and Adj. Terr. (Hayden Surveys),1874, p. 426. 3 Idem, p. 266. * Idem, pp. 266-277. COLORADO PLATEAUS 2S1 Dolores River, a tributary of the Grand. The Dolores rises in the SanJuan Mountains, runs south and west for more than 30 miles, then flowsnorthwest against the inclination of the s
Forest physiography; physiography of the United States and principles of soils in relation to forestry . ordwith the present slope of the plateau surface (p. 284) is that of the 1 F. V. Hayden, U. S. Geog. and Geol. Surv. of the Terr., 1875, pp. 340, 341, 349. 2 Henry Gannett, U. S. Geol. and Geog. Surv. of Col. and Adj. Terr. (Hayden Surveys),1874, p. 426. 3 Idem, p. 266. * Idem, pp. 266-277. COLORADO PLATEAUS 2S1 Dolores River, a tributary of the Grand. The Dolores rises in the SanJuan Mountains, runs south and west for more than 30 miles, then flowsnorthwest against the inclination of the surface for about 60 miles to theGrand River in western Colorado, in a gradually deepening canyon,Fig. 78. At the turning point it is in a canyon only 100 feet deep;above and below this point the canyon deepens to 2000 feet. Evidentlythe river gained its course sometime before the present surface con-ditions were established. The surface is structural in origin, beingdeveloped on a great sandstone layer (Dakota). Either the surface waspeneplaned and the river now pursues an antecedent course with re-. Fig. 78. ? ? Canyon of the Dolores. The canyon is 2000 feet deep at a, 2100 at h, and 100 at c.(Hayden Surveys.) spect to later uplifts that deformed the peneplain, or its course wasdeveloped in response to a structural slope that has since been the main stream has thus maintained its earlier course thesmaller streams of the region show marked responses to the presentattitude of the surface. The tributaries of the San Juan (south) risealmost on the brink of the Dolores canyon, for they have been extendedin response to the structural surface now existing and have encroachedon the weaker Dolores tributaries until the latter are all but extinguishedsouth of the canyon.^ The Yellow Jacket tributary of the San Juan has encroached so far upon the Dolores at thegreat bend that a tunnel several hundred yards long has been constructed through the in-tervening barrier and a la
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectforestsandforestry
