ABSTRACTS AND DISCUSSIONS OF PAPERS 411 



PROBLEM OF CORRELATION BY USSE OF VERTEBRATES 

 BY WILLIAM D. MATTHEW 



CORRELATION AND CHRONOLOGY ON THE BASIS OF PALEOGRAPHY 



UY CHARLES SCHUCHERT 



On account of the absence of Dr. F. H. Knowlton, the reading of his 

 paper, entitled "Correlation based on a study of tlie history of plants," 

 was postponed to a later meeting. 



Discussion of the preceding three Papers 



Doctor Matthew stated that the ultimate displacement of straud-lines is 

 satisfactory for wide-spread movements, but in a practical application it is 

 doubtful whether such movements are in unison. 



Prof. J. P. Smith stated that in the case of the Triassic rocks of the West 

 correlation has l)een purely by paleontology. 



In correlating the Lower Cretaceous strata, Dr. T. W. Stanton stated that 

 paleontology alone has been used. It was conceded that for practical purposes 

 correlation is by paleontology, but that ultimate correlation depends on dias- 

 trophism. 



Professor Schuchert bi'iefly reviewed Suess' conception of the great overlap 

 in the Cretaceous and his application of this principle to the Devonian, and 

 considered the Pacific province in this connection. He called attention to the 

 fact that the middle of a period is characterized by the most <-osmopolitan 

 fauna. 



Professor Osborn called attention to the importance of fossils as compared 

 with diastrophic movements when used for correlation purposes, and empha- 

 sized the stability of protoplasm thi-ough the past as r-onti-astod with our 

 standards of permanence in the inorganic world. 



Professor Willis called attention to the insufficiency of our knowledge con- 

 cerning diastrophism. He contrasted the gradual changes in the Mississippi 

 liashi with the su<lden changes on the Pacific coast, and questioned the univer- 

 sality of movements. The .Vtlantic and the I'acilic are separate dynaniic basins 

 which are discordant in their movements. It is necessary to \v()rk out the 

 paleogeography in as great dctiiil -Jis i)ossible. 



Doctor Ulkich remarked that in consid<>ring diastrophism we should note 

 especially tlio.se movements felt over broad areas. lie believed in the correla- 

 tit)n of submergence in one region with emergence in aiidtbcr. 



Professor Mekriam in summarizing stated that the present discussion was a 

 necessary preliuiinary to any consideration of correlation between the Pacific 

 and Atlantic basins. He noted that the consensus of opinion seenied to be that 

 organic criteria fiuTiish the tools actually nst-d in practicall.\ all wide-range 

 correlation. Att(iiti<Mi w.is directed to the importance of the liistory of life 

 as a basis or scale U>v use in lime nieasiu'emeiit or classification. 



Tlie meeting tlien adjourned. 



