254 



CHARLES KEYES 



GENERAL GEOLOGICAL SECTION OF NEW MEXICO— Continued 



For general completeness the New Mexican rock-pile stands 

 facile princeps among American geological sections. Being at once 

 both a critical and a standard terranal succession for the continent, 

 it merits and invites closest inspection, carefulest evaluation, and 

 widest comparison. It reflects regional crustal movements along 

 a primitive continental plait more directly and more perfectly 

 than perhaps any other known section. Amplitude of diastrophic 

 oscillation is sufficiently large and sharp to make this a direct basis 

 of genetic taxonomy. It admits of orotaxial classification of 

 geological formations at its best. 



