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FIRST YEAE SCIENCE 



When rain falls upon a sloping surface of fine textured, 

 easily eroded material not covered thickly with vegetation, 

 this will be deeply and fantastically sculptured. An excel- 

 lent example of this kind of sculpturing is found in the 

 Bad Lands of Dakota. Here travel is exceedingly difficult. 

 It was in these natural fastnesses that the Sioux Indians 

 made their last ineffectual stand against the white man's 

 civilization. 



DIVIDES BETWEEN STREAMS. 



The ridge in the center of the picture separates two streams flowing in 

 opposite directions. 



156, Divides. If we carefully observe the drainage of 

 a region, we find that the areas from which different 

 streams gather their water are usually so distinctly sepa- 

 rated from one another that a line could be drawn so that 

 wherever water falls the rivulets on one side would flow 

 into one stream and on the other side into another. Such 

 a line of the highest land between the drainage areas of 

 neighboring streams is called a divide. The line may be 



