SCIENCE OF FOSSIL REMAINS 333 



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 LYELL, 1797-1875. 



forms indicates a continual process of development of animal 

 life ; and that the disappearance of some forms, that is, their 

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

 gradual changes. When this view was accepted, it overthrew 

 the theory of catastrophism and replaced it by one designated 

 uniformatism, based on the prevalence of uniform natural 

 laws. 



This new conception, with all of its logical inferences, 



