SCIENCE OF FOSSIL LIFE 



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slow, continuous changes that have occurred in the past and 

 have molded the earth's crust into its present condition. 



He showed, further, that organic fossils are no exception 

 to this law of uniform change. He pointed to the evidences 

 that ages of time had been required for the formation of the 

 rocks bearing fossils; and that the regular succession of animal 



Fig. 97. — Charles Lvell, 1797-1S75. 



forms indicates a continual process of develo])ment of animal 

 life; and that the disa})])earance of some forms, that is, their 

 becoming extinct, was not owing to sudden changes, but to 

 gradual changes. When this view was accei)ted, it overthrew 

 the theory of catastrophism and replaced it b}- one designated 

 uniformatism, based on the ])revalence of uniform natural 

 laws. 



This new concei)tion, with all of its logical inferences. 



