124 DARWINISM AND THE PROBLEMS OF LIFE 



a wide gap between the new organisms and those 

 buried in the older stratum, representing the time 

 during which the earlier stratum was dry land. Thus 

 we can understand the gaps in the passage from one 

 species of fossils to another. Further, we can see from 

 the nature of this sole means of preserving animal 

 remains that land-animals can leave us no trace of their 

 existence, or at all events only if they are carried into 

 the water by accident and deposited quietly at the 

 bottom of it. 



But there will be a still further reduction in the 

 number of animal remains preserved. All the seas of 

 former days were not fed by rivers that brought mud 

 to them, and in those without slimy bottoms animal 

 remains would decay. Moreover, remains might not 

 be preserved that fell into the water at places where 

 the rivers brought down coarse debris into the sea, 

 which would grind everything up. 



Further, when the fossiliferous strata were raised out 

 of the sea their contents were exposed to fresh dangers. 

 An enormous amount was destroyed by weathering, 

 rain, floods, and surge, carried away by the rivers and 

 ground down into mud again, and so had to begin the 

 cycle afresh. And when the crust of the earth burst, 

 became creased or folded, and threw up chains of 

 mountains, many remains were squeezed until they 

 became unrecognisable. 



Besides all this, the sea still holds from us 

 incalculable treasures, and there are others in lands that 

 have not yet been opened up. When we further 

 remember how few of the remains that are found come 



