Forest physiography; physiography of the United States and principles of soils in relation to forestry . tracts of broad flat structuralsurfaces from which younger formations have been eroded. TheBoston Mountains are capped by thin layers of sandstone and shale,the more resistant sandstone governing the physical features of themountains. The rocks dip in the main to the south at an angleslightly greater than the general southward slope of the surface. Fromhilltops on the Springfield Plain the Boston Mountains appear as abold, even escarpment with a level crest, but on closer examination theesc
Forest physiography; physiography of the United States and principles of soils in relation to forestry . tracts of broad flat structuralsurfaces from which younger formations have been eroded. TheBoston Mountains are capped by thin layers of sandstone and shale,the more resistant sandstone governing the physical features of themountains. The rocks dip in the main to the south at an angleslightly greater than the general southward slope of the surface. Fromhilltops on the Springfield Plain the Boston Mountains appear as abold, even escarpment with a level crest, but on closer examination theescarpment is seen to have many finger-Hke extensions to the north PLATEAUS AND RANGES OF THE PLAINS COUNTRY 453 in the form of ridges and foothills. Toward the west the BostonMountains decline in elevation and in ruggedness as the sandstonebeds become thinner and more shaly in that direction. The Boston Mountains on the southern border of the Ozark provinceowe their dominating height in part to the excessive erosion of the regionnorth of them and in part to differential uplift.^ The result of erosion. Fig. 170. —• Topography of the Ozark region. (Purdue, U. S. Geol. Surv.) was to reduce a large part of the Ozark region in Missouri and Arkansasto a comparatively low altitude, leaving the Boston Mountains as re-siduals and their front as a rather bold escarpment. The former greaterextent of the Boston Mountains is indicated by remnantal outliersstanding several hundred feet above the general level of the area aboutthem. In contrast to the northern part of the Ozark region, which isa low fiat dome with only local faulting and minor undulations, the > A. H. Purdue, Winslow Folio U. S. Geol. Surv. No. 154, p. 5, col. 4. 454 FOREST PHYSIOGRAPHY Boston Mountains have a monoclinal structure and a correspondinglysteeper border topography. The topographic forms of the Ozark region are those characteristicof early maturity in a region of nearly fiat-bedded rocks of varyinghardness in
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectforestsandforestry
