140 ■ Repokt of the State Geologist. 



of Cuvier, formulated the conclusion that animated nature must 

 have become extinct and been again renewed twenty-seven times." 

 He divided the fossiliferous deposits into twenty-seven stages sep- 

 arated into groups of unequal value and each characterized by its 

 special fauna. This classification was made with such care that 

 in its general terms it has remained to the present day; its 

 denominations have for the most part been retained, although 

 new researches and new ideas have brought some changes into 

 the stratigraphic groupings. The same can not be said of the 

 theories which led d'Orbigny to his conclusions. As early as 

 1813, VON Schlotheim refused to admit that each particular 

 layer was the result of a new revolution of nature. Bronn 

 demonstrated that certain species indeed really passed from one 

 formation to another, and though stratigraphic boundaries are 

 often barriers confining the persistence of some form, still this is 

 not an absolute rule, since the species in nowise appear and 

 again disappear in their entirety. Lyell (1>^32) forever destroyed 

 the hypothesis, up to his time generally accepted, of cataclysms 

 and universal revolutions of nature. His theory of existing 

 causes consists in this, that all the phenomena which have 

 occurred on the surface of the globe during past times are of the 

 same nature with those which are occurring at the present time. 

 "We see in the whole, and in parts also, the results of those phe- 

 nomena, but we must admit that their occurrence must have 

 required considerable time. These new ideas, unreservedly 

 adopted by the whole learned world, opened a most propitious 

 way for the theories of transformation. The changes effected 

 in faunas must have been slow alid long continued, as are all 

 geologic phenomena ; and it was but one step farther to arrive 

 at the admission that faunas were derived one from another. 

 Sir Charles Lyell, at the beginning a partisan for the immu- 

 tability of specie s, rendered, with an impartiality rare among 

 scientists of that opinion, full justice to the essays of Lamarck. 

 The exposition of the doctrine of transformation by Darwin 

 quickly convinced him, and the theor}^ of Evolution has not 

 found among geologists a warmer or more eloquent partisan than 

 the great English scientist. 



The theory of Evolution received at first a very unfavorable 

 reception, and was consequently unable to exert any great influ- 



