This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 Excerpt: ...lands; they reduce the slope and thereby lessen the run-off and corrasion. Fig. 116.--Cheeking of soil erosion by brush dams. (U. S. Geological Survey.) Bad land topography is due to excessive gullying, Fig. 118. It occurs most typically in portions of western Nebraska, Wyoming and the Dakotas where incoherent ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 Excerpt: ...lands; they reduce the slope and thereby lessen the run-off and corrasion. Fig. 116.--Cheeking of soil erosion by brush dams. (U. S. Geological Survey.) Bad land topography is due to excessive gullying, Fig. 118. It occurs most typically in portions of western Nebraska, Wyoming and the Dakotas where incoherent materials, scanty soil cover and torrential rainfall are favoring conditions. Such areas are chiefly valuable for grazing, but excessive grazing by reducing the cover will aid in the development of this topography. Extensive bad land areas have been Fig. 117.--Terraces in Central China. The terraces both reduce erosion and aid in making the steep hill sides available for cropping. (Willis, SmithsoniaD Institution.) produced in the loose materials of the Lafayette Formation in some of the Southern states by neglect of the soil cover. Stream Transportation Factors.--The familiar fact that streams carry materials, or load as it is called, has been noted under the topic of corrasion. It is a matter of common observation that streams in high water and with consequent greater velocity can carry larger and heavier masses than the same streams at low water with slower current. The carrying power of streams increases very rapidly with the velocity for, if a stream's velocity is doubled, the carrying power is increased 64 times or, in other words, the transporting power of a current varies as the sixth power of the velocity. With this in mind one can understand how a small stream in flood can transport even large boulders. The efficiency of velocity in stream transportation is illustrated by the jetties which were built at one of the mouths of the Mississippi River. In order to overcome the tendency of the river to deposit its sediment and obstruct the channel, ...
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Seller's Description:
Good. No Jacket. Textbook. 8vo-over 7¾"-9¾" tall. 382 pages. Green boards are lightly scuffed with edgewear, spine has darkened. Fep is missing. Pages are clean, text unmarked, binding is tight.
