82 Charles Schuchert — Historical Geology, 1818-1918. 



widely used either in Great Britain or on the Continent, 

 but in the last twenty years has been accepted more and 

 more widely in America. Even here, however, it is in 

 direct conflict with the term Champlain, proposed by the 

 New York State Geologist in 1842. 



In 1897 the International Geological Congress pub- 

 lished E. Renevier's Chronographie Geologique, wherein 

 we find the following : 



,2 



m 



Upper or Silurian f Ludlowian (Murchison 1839). 



(Murchison, re- ■< Wenlockian (Murchison 1839). 



stricted, 1835). [_ Landoverian (Murchison). 



Tv,r-^i c\ a • •„ f Caradocian (Murchison 1839). 

 Middle or Ordovician I T -. .,. a-- ,. 100m y 



(Lapworth 1879). \^^^^^; 



Lower or Cambrian f Potsdamian (Emmons 1838). 

 (Sedgwick, re- ■< Menevian (Salter and Hicks 1865) 

 stricted, 1835). L Georgian (Hitchcock 1861). 



Eegarding this period, which, by the way, is not very 

 unlike that of Barrande, Eenevier remarks that it is "as 

 important as the Cretaceous or the Jurassic. Lapworth 

 even gives it a value of the first order equal to the Pro- 

 tozoic era." 



In the above there is an obvious objection in the double 

 usage of the term Silurian, and this difficulty was met 

 later on in Lapparent's Traite by the proposal to substi- 

 tute Gothlandian for Silurian. Of this change Geikie 

 remarks : i ' Such an arrangement . . . might be adopted 

 if it did not involve so serious an alteration of the nomen- 

 clature in general use." On the other hand, if dias- 

 trophism and breaks in the stratigraphic and faunal 

 sequence are to be the basis for geologic time divisions, 

 we cannot accept the above scheme, for it recognizes 

 but one period where there are at least four in nature. 



Conclusions. — We have arrived at a time when our 

 knowledge of the stratigraphic and faunal sequence, plus 

 the orogenic record as recognized in the principle of 

 diastrophism, should be reflected in the terminology of 

 the geologic time-table. It would be easy to offer a satis- 

 factory nomenclature if we were not bound by the law of 

 priority in publication, and if no one had the geologic 

 chronology of his own time ingrained in his memory. 

 In addition, the endless literature, with its accepted 

 nomenclature, bars our way. Therefore with a view of 



