174 The Rocks of the John Day Valley. 



animals lived there when they lived here. 

 Their remains are found, even to identity of 

 species, from Nebraska to New Mexico. It 

 is difficult to assign their destruction there to 

 the same causes that destroyed them here, or 

 to any cause operating at once over a whole 

 continent, while the climate remained un- 

 changed and food continued abundant. On 

 the other hand, the supposition of the escape 

 of a portion from these destroying agencies 

 meets, among others, this difficulty: when 

 here in this John Day valley quiet had been 

 again restored, the hills had been again 

 clothed in verdure and the waters had precipi- 

 tated not only, but covered out of sight, their 

 vast strata of volcanic ashes, then animal life 

 returned, too, but not the same that had pre- 

 viously existed. The whole fauna was 

 changed, and even where the same type was 

 restored, as in the case of the horse, it is in 

 some new species; the old had passed away, 

 and forever. 



If any one supposes that all the difficulties 

 that beset these lines of inquiry and research 



