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BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA^ 



Vol. 27, pp. 451-490 June 23, 1916 



proceedings of the paleontological society 



iO 



1 



COPKELATION BY DISPLACEMENTS OF THE STRAND-LINE 



AND THE FUNCTION AND PKOPEE USE OF 



FOSSILS IN COREELATION 1 



BY E. 0. ULEICH 



(Read before the Paleontological Society August $, 1915) 



CONTENTS 



Page 

 Introduction 452 



Effect of varying circumstances on principles and criteria of correla- 

 tion 452 



Influence of bottom and depth on marine faunas 454 



Preceding papers on the subject of correlation 455 



New criterion in correlation 455 



True function of fossils in stratigraphic taxonomy 457 



Methods of correlation 457 



Uniformity and consistency in practice essential 457 



Unconformities in the Cambrian sandstones at Ablemans, Wisconsin . . 459 

 Unconformable contact of Cambrian and Ozarkian sandstones near 



Madison, Wisconsin : 460 



Continental seas usually small and frequently withdrawn 461 



Prevailing inconsistencies in drawing the Ordovician-Silurian bound- 

 ary 463 



Discordant testimony of land and marine organic remains 464 



Bearing on the age of the Ohio and Chattanooga shales 465 



Revised methods and principles of correlation and classification 466 



General discussion 466 



The ultimate basis of classification 467 



Recent instances showing advantages of the diastrophic method 470 



Correlation by "matching" of fossil contents 472 



Causes of mutation and extinction of marine species 474 



Generic alliances among pelagic organisms insufficient to establish 

 contemporaneity of deposits 476 



1 Published by permission of the Director of the U. S. Geological Survey. The terms 

 Ozarkian, Canadian, St. Croixan, and some details of classifications as used in this paper 

 have not yet been adopted by the Survey. 



Manuscript received by the Geological Secretary April 6, 1916. 



This paper was read at the Summer Meeting of the Paleontological Society, at the 

 University of California, August 3, 1915, and was the first of a symposium entitled 

 "General consideration of paleontologic criteria used in determining time relations." 



XXXIII — Bull. Geol. Soc. Am,. Vol. 27, 1915 (451) 



