EFFECTS OF THE MOVEMENTS OF WATER 31 



in the sea (see Fig. 7), and have in them imprints of the 

 bodies of animals that lived in those days. These imprints 

 of ancient animals 

 are called fossils (see 

 Figs. 8 and 9). 



The average rain- 

 fall of the United 

 States each year is 

 about thirty inches. 

 It is estimated that 

 about one-half of 

 this water evapo- 

 rates, about one- 

 third of it runs off 

 over the surface, and one-sixth sinks into the ground. 

 Let us think for a while about that one-sixth that sinks 

 into the ground. 



Ground- Water. For at least two reasons, ground- 

 water is very important to man: (i) it nourishes plants; 



(2) it supplies wells 

 and springs. We all 

 get our food from 

 plants, and over hah" 

 the people in the 

 world get their drink- 

 ing water from wells 

 and springs. 



Rain-water finds 

 its way into all the 

 cracks and pores in 

 Flo. 9. Fossil*. the soil, but the 



