HOW TO CARE FOR SOIL 331 



by water is much more noticeable than the erosion caused 

 by wind. You can notice evidence of erosion during 

 every summer shower. Water flowing on the street, or 

 in ravines in the country, is made muddy by the small 

 particles of solid matter that it is carrying. Ditches of 

 various sizes on slopes and hillsides and the ravines 

 through which the water runs were made by the flowing 

 water and are evidence of rapid erosion. Most valleys 

 are results of water erosion. The hills usually contain 

 rock that is not easily decomposed and carried away by 

 the water; for this reason they have remained longer 

 than the earth that was carried away between them, 

 but they, too, are slowly being carried away. 



Water flowing in creeks and rivers, carrying sand, 

 gravel, and at times stones that weigh hundreds of pounds, 

 grinds the rocks in the beds of the streams into finer and 

 finer particles, and also digs into the banks on either side. 

 The water cutting into the banks of the stream causes it 

 to widen its course and to flow back and forth across its 

 valley; but a valley is not made until the bed of the 

 stream is cut down to a comparatively low level. Make 

 a careful examination of ditches on the hills or in the 

 fields. Notice the influence of vegetation, such as grass, 

 crops, or trees, on erosion. Observe the work done by 

 creeks or rivers, and also the shape and width of the 

 valleys. 



Erosion caused by the waves beating against the shores 

 of lakes and oceans is also very evident. The wind some- 

 times causes the water to form waves several feet high, 

 and these waves beat against the shores and rocky cliffs, 

 sometimes with tons of force, and the rocks lying at the 

 base of a cliff are gradually ground to sand and carried 

 out into deeper water. 



