272 T. W. STANTON DAKOTA SANDSTONE PROBLEMS 



within the Cretaceous have tried to harmonize the American with the 

 European classification by restricting Comanchean to the pre-Washita 

 rocks. A more artificial systemic boundary could hardly be drawn. No 

 one well acquainted with the Comanche fauna and with the field relations 

 of the Comanche rocks could accept such a boundary between systems, or 

 such a restriction of Comanche, which is now applied to a perfectly nat- 

 ural provincial series. 



In southern Texas, on Devils River and on the Pecos, as has been stated 

 by Dumble and other Texan geologists and confirmed by my own field 

 observations, there is a complete lithologic transition from the Fredericks- 

 burg to the Washita and a recurrence of the Fredericksburg faunal facies 

 high in the Washita rocks just beneath the Del Eio formation. I refer 

 to the persistence of the Edwards limestone type of lithology in the equiv- 

 alent of the Georgetown limestone, and the recurrence of the Edwards 

 faunal facies, characterized by certain rudistid and nerinean types, above 

 beds with characteristic Georgetown fossils. Making due allowance for 

 differences in fauna due to littoral, deeper water, and reef facies, all of 

 which are present in the Comanche, the entire Comanche fauna is a unit 

 showing only such progressive changes as are to be expected within a 

 series. 



From all these considerations and from others which can not be de- 

 tailed here, the conclusion is reached that the Comanche series as defined 

 by R. T. Hill is a good provincial series, but in my opinion the term 

 should be restricted to rocks in Texas and Mexico, and to those of adja- 

 cent regions that can be strictly correlated with them. Its application as 

 a series term to the Lower Cretaceous of the Pacific coast is not justified 

 by the present state of knowledge, and the recognition of Comanchean as 

 a system of world-wide application is still less justified. 



