BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 16, pp. 137-150 March 15, 1905 



BEARING OP SOME NEW PALEONTOLOGIC FACTS ON 



NOMENCLATURE AND CLASSIFICATION OF 



SEDIMENTARY FORMATIONS 



BY HENRY SHALER WILLIAMS 



(Read before the Society December 29, 190J/) 

 CONTENTS 



Page 



Summary of writer's views previously expressed 137 



Suggested modification of rule 14 138 



Views of Huxley and Geikie 138 



Illustrations of importance of stratigraphic rather than time basis 140 



In general 140 



Monterey, Romney, and Jennings beds of Virginia and West Virginia. . . 140 



Catawissa section of Pennsylvania 140 



Devonian section of Genesee valley, New York 141 



General discussion of the three typical illustrations 141 



Analysis of the faunas 143 



Interpretations and conclusions 144 



Geological usage of term fauna 145 



Summary and conclusions 147 



Summary of Writer's Views previously expressed 



It was suggested by the writer, in a paper read before the Geological 

 Society in 1893* that duality of nomenclature was desirable in order to 

 discriminate between the divisions of the time scale and those of the for- 

 mation scale, and later (1902-'3), when the revised rules of nomenclature 

 and classification were being prepared by the United States Geological 

 Survey ,f it was still thought that the two scales might be discussed sep- 

 arately if only the criteria of discrimination and the nomenclature were 

 kept strictly distinct. In 1903, J: in a paper published in the Bulletin of 

 this Society, the shifting of faunas during the continuance of their bio- 

 logical integrity was shown to be a fact, and it was pointed out that 

 consequent precaution was necessary in using fossils with precision in 



♦Journal of Geology, vol. 2, pp. 145-1G0. 



tSee Twenty-fourth Annual Report U. S. Geol. Survey, pp. 21-27. 



{See vol. 14, pp. 177-190. 



XIX-Bui,l. Geol. Soc. Am., Vol. 16, 1904 (137) 



