20 THE OCEAN RIVER 



outer crust of granite still covered the remainder of the earth's 

 surface, but in the region of the moon's scar the underlying 

 basalt was exposed and immediately began to solidify. The 

 solid granite skin, exposed to great strain, is believed to have 

 cracked in a number of places. 



A. Relative position of fragments of Earth's crust immediately after the sepa- 

 ration of the Moon, according to one theory. 



B. This is how the map of the world might look today if the separation of 

 continents had not been stopped by the congealing of the basalt ocean. 



