534 



River-slopes. 



direction in which the arrows point in the following 



diagram : 



FIG. 107. 



If the banks be high, they almost always have the 

 shape shown in the section lines a and b across two of 

 the greater curves of the river. The water rushing on 



FIG. 108, a. 



is projected with great force against the concave part 

 of the curve, c, fig. 108, and in like manner it is 

 again strongly projected against the concave cliff, d, 



FIG. 109, ft. 



fig. 109. The result is, that the water wears back 

 the cliffs, c and d ; or, what tends to the same end, 

 in conjunction with the wearing action of the water, 

 the debris, loosened by atmospheric causes on the steep 

 slopes, c and d, readily slips down to the level of the 

 river, and is carried away by the force of the stream, 

 thus making room for further slips. 



