74 THE OLD SHIELDS 



an even older orogenetic cycle, and the greater the chance that during 

 some subsequent orogeny the crust became mobilized, with the re- 

 sulting geosynclines destroying all earlier fossils through metamor- 

 phism and recrystallization. So, the older the rock, the greater the 

 chance that some unfortunate mishap has destroyed any fossils which 

 it might possibly have carried. This, in combination with the fact 

 that all early life was of a microbic nature, will explain the meagre 

 fossil finds of early life on earth. The abundant fossils from the 

 Cambrian onward are 'only' ^/a billion years old at most. Research 

 into early life and its origin brings us back to the 1 billion and 

 2 billion, and even to the 3 billion-year age bracket. 



