40 WHAT EVOLUTION IS 



different from that given by the mod- 

 ern naturahst. When they discov- 

 ered the impressions of shells in the 

 rocks of the mountainside they recog- 

 nized at once the inappropriateness 

 of the situation, and they believed 

 that they had before them evidence 

 of nature's unsuccessful effort to 

 produce new life. She, in her prod- 

 igality of productiveness, had started 

 the formation of an aquatic animal 

 on a mountainside and, in conse- 

 cjuence of the unfavorableness of 

 the site, the process had failed of 

 completion and a mere trace of its 

 beginning was thus left stranded in 

 inhospitable surroundings. 



This general view of the nature of 

 fossils was current for many gener- 

 ations, but as early as the fifteenth 

 century, Leonardo da Vinci (1452- 

 15 19) recognized that shore lines 

 shifted, that the earth's crust was ele- 



