PREFACE 



the evidences of immense time that looked out from 

 their gray and crumbHng fronts. I was in the pre- 

 sence of Geologic Time, and was impressed by the 

 scarred and lichen-coated veteran without knowing 

 who or what he was. But he put a spell upon me 

 that has deepened as the years have passed, and 

 now my boyhood ledges are more interesting to me 

 than ever. 



If one gains an interest in the history of the earth, 

 he is quite sure to gain an interest in the history of 

 the life on the earth. If the former illustrates the 

 theory of development, so must the latter. The 

 geologist is pretty sure to be an evolutionist. As 

 science turns over the leaves of the great rocky 

 volume, it sees the imprint of animals and plants 

 upon them and it traces their changes and the ap- 

 pearance of new species from age to age. The bio- 

 logic tree has grown and developed as the geologic 

 soil in which it is rooted has deepened and ripened. 

 I am sure I was an evolutionist in the abstract, or 

 by the quality and complexion of my mind, before 

 I read Darwin, but to become an evolutionist in 

 the concrete, and accept the doctrine of the ani- 

 mal origin of man, has not for me been an easy 

 matter. 



The essays on the subject in this volume are 

 the outcome of the stages of brooding and think- 

 ing which I have gone through in accepting this 

 doctrine. I am aware that there is much repeti- 



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