Forest physiography; physiography of the United States and principles of soils in relation to forestry . hern part of the Three Forks district.^ The last geologic episode which has had an influence on the topog-raphy and drainage of the district has been glaciation, but the glacierswere local and the drift deposits in the valleys are of local origin. Thelow elevation of the ranges, 7000 to 10,000 feet, did not allow vigorousglaciation, and glacial forms have weak expression except in a few favor-able localities. MINOR RANGES OF WESTERN MONTANA In western and southwestern Montana is an extensiv
Forest physiography; physiography of the United States and principles of soils in relation to forestry . hern part of the Three Forks district.^ The last geologic episode which has had an influence on the topog-raphy and drainage of the district has been glaciation, but the glacierswere local and the drift deposits in the valleys are of local origin. Thelow elevation of the ranges, 7000 to 10,000 feet, did not allow vigorousglaciation, and glacial forms have weak expression except in a few favor-able localities. MINOR RANGES OF WESTERN MONTANA In western and southwestern Montana is an extensive area hemmed inby the Madison, Jefferson, and other ranges on the south and the Lewis,Livingston, and other ranges on the north. On the east it extends tothe Big Belt Mountains, on the west to the Bitterroots, Fig. 86. Thetract includes no prominent mountain chains, only short ranges whichreach up to a more or less common level. The geologic conditions aresomewhat complex, the rocks consisting of greatly deformed sedimen- 1 A. C. Peak, Three Forks Folio U. S. Geol. Surv. No. 24, 1896, p. i, col. Fig. 99. — Effects of slope exposure on forest distribution, western Montana, looking east from ; see topographic map below. A and C are cool, moist, forest-clad northern exposures,B and D are warm, dry, unforested southern exposures. The trees in the foreground grow on a north-eastern exposure. For the position of these slopes on the map see corresponding letters in Fig. 100.(Barrel!, U. S. Geol. Surv.)
Size: 2378px × 1051px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectforestsandforestry
