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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e. The surface of the Driftless Area is topographically mature and thedrainage is well organized, without falls and rapids and lakes orsv/amps except within narrow limits and along the river bottoms.The aimless flow of streams developed upon the irregular topographycharacteristic of till sheets or terminal moraines, as well as the abun-dant swamps, lakes, and ungraded stream courses of such localities, arehere practically absent. At numberless points within the area over-ridden by glacial ice the bedrock is scratched, grooved, and smoothed,while within the Driftless Area glacial markings are entirely absent.^The thoroughly dissected upland plain of the Driftless Area is in strik-ing contrast to the more even country with drift-filled valleys aboutit. The valleys and ravines tributary to the main streams have beenthoroughly organized and the divides reduced to narrow ridges. The 1 Grant and Burchard, Lancaster-Mineral Point Folio U. S. Geol. Surv. No. 145, igo7,p. I. PRAIRIE PLAINS 495
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Scale of Miles Fig. ig2. — Driftless Area of Wisconsin. valley bottoms toward the south are from 600 to 700 feet above sealevel, and the relief of the area is from 200 to 300 feet.^ In spite of the extreme irregularity of the drainage of the glaciatedregion its relief is less than that of the Driftless Area, a condition dueto the manner of distribution of the drift, which in general was lodgedin the valleys more freely than on the heights. Such plain-like qualitiesas the drift-covered region exhibits are due less to the glacial denudation 1 J. E. Carman, The Mississippi Valley between Savanna and Davenport, Bull. 111. StateGeo!. Surv. No. 13, igog, p. 2g. 496 FOREST PHYSIOGRAPHY of prominences than to the grading up of depressions. In a roughmanner the driftless region therefore presents the essential features ofthe preglacial topography of this portion of the United States.^ The purely residual products in the Driftless Area have their greatestexpression upon the flat-topped upland

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