CHAPTER IV 



The story of the rocks. Contributions of paleontology to 

 evolution. Rise and fall of the faunas of the past. 



Not alone by a comparison of the structure of living forms 

 and their development, can we decipher the writings of 

 evolution upon the page of time. Perhaps even more con- 

 clusive is the story of the life which is no more, of the faunas 

 and the floras of the past. For in the record of the rocks 

 there pass in review before us the generations of the ages 

 telling us the story of how life has come to be. Therein we 

 can read in a moment the tale of a million years. 



Among other facts it was the existence of the extinct faunas 

 of South America which first turned Darwin's thought into 

 the channel of evolution. Yet in spite of its contribution to 

 our knowledge of evolution, there are many pages missing 

 from the record, many of which doubtless may some day be 

 found, more probably lost forever. These ''missing links" 

 of the palaeontologist have ever been a ready refuge for the 

 dwindling forces of the opposition, attempting with broom- 

 stick arguments to hold back the rising tide of facts. Many 

 species of animals and plants, especially the more minute' and 

 the more primitive forms are lacking in hard parts and are 

 not readily preserved. Some may have been destroyed in the 

 upheavals of the earth. Still others are doubtless awaiting 

 the pick of the geologist, which has as yet but scratched the 

 earth's surface here and there. Thus does the palaeontologist 

 explain the gaps in his record where the story is not complete. 



The student of world history written in the text book of 

 the rocks need not trouble himself with dates, for the sequence 

 and causes of events rather than their times are what nature 

 strives to teach us. But the mind of curious man never is 

 content unless speculating regarding the unknown, and so 

 geologist, biologist and physicist have all endeavored from 

 different data to form estimates of the age of the earth and 

 its geological periods. Without detailing their methods it is 

 sufficient to say that no very close agreement exists among 

 them, the geologists claiming from 100,000,000 to 800,000,000 

 years since the oldest rocks were formed, the biologist asking 

 for hundreds of millions of years for the development of life, 



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