26 To the River Plate and Back 



he was even then a comparatively modern form of life, 

 the product of an evolution which had been going on 

 for aeons before his advent!' 



Will there ever come a time when the prophetic 

 declaration, There shall be no more sea,' shall be 

 fulfilled? It is possible. Swinging out there in the 

 night is the full-orbed moon. There are no seas or 

 oceans upon it, but it is literally covered with volcanoes. 

 A glass of only moderate power reveals the peaks and 

 the craters. These volcanoes are the best proof pos- 

 sible that at one time there must have been an abun- 

 dance of water on the surface of the moon. We know 

 how volcanoes are formed. Water sinking down into 

 the earth, which is still hot in its interior, is gradually 

 heated and becomes steam. When the pressure of the 

 steam reaches a certain point there is an explosion 

 and a pyramid of mud or of lava is thrown up. We 

 know that water is necessary to the formation of lava. 

 The constituent minerals in the primitive rocks in the 

 presence of water may be converted into lava at com- 

 paratively low temperatures. The volcanoes on the 

 moon show that this little attendant globe was once 

 covered by seas. They are invisible now. What has 

 become of them? They have been simply sucked down 

 into the rocks as the moon grew colder and colder, 

 just as water is sucked up by a sponge. The same thing 

 may happen to our old world in future ages. And the 

 air may at last go the way of the water, as it apparently 

 has gone in the moon, which has no atmosphere. 



