THE EARTH THE ABODE OF LIFE 



lakes are between Daun and Manderscheid. There are, 

 of course, many other and larger crater lakes in existence, 

 but we select these because they are so easily accessible. 



The flow of the lakes into one another followed. 

 Innumerable lakelets developed into rivers or chains of 

 lakes on the surface of the young planet, continually 

 becoming larger bodies of water, till they developed into 

 the vast irregular oceans of to-day. This evolution is of 

 great importance from a geological point of view, because 

 it leads the way to the origin of the ocean basins and the 

 great platforms of land which we call continents. It is 

 easy to see that because of the weight of water in the 

 depressions the earth under the waters tended to become 

 more and more depressed, so that the water areas tended 

 to grow larger and deeper. The wash of earths from the 

 land tended to build its borders out into the water basins, 

 but the deepening and spreading of the water basins is 

 believed to have been the most marked feature of the 

 earth's early growth. All this time the earth was grow- 

 ing in diameter and circumference. 1 When this growth 

 ceased other causes and effects came into play, and the 

 proportions of sea and land became better balanced. 



There is nothing in our human knowledge to tell 

 us with certainty when or how life first appeared on the 

 earth. We have already spoken of animal and vegetable 

 remains that for ages are preserved in the rocks. But 

 clearly no such remains could ever be found in the 



i For reasons which are a little too complex to be considered 

 here. We can only indicate the general line of reasoning by saying 

 that the central heat as it moved outwards from the rocks nearer the 

 surface expanded them. 



no 



