BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 VOL. 27, PP. 525-530 SEPTEMBER 1, 1S16 



PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



PEINCIPLES GOVERNING THE USE OF FOSSIL PLANTS IN 

 GEOLOGIC CORRELATION 1 



BY F. H. KNOWLTON 



(Read before the Paleontological Society August S, 1915) 



CONTENTS 



Page 



Introduction 525 



Standard sections 526 



Recurrent floras unknown 527 



Rapidity of plant migration 527 



Use of plants in evaluating geologic hiatuses 528 



Method of correlation by fossil plants 529 



Introduction 



Although it may already have been more ably done by the preceding 

 speakers in this symposium, a brief outline of the general underlying 

 principles may not be wholly out of place as an introduction to the topic 

 assigned me. 



Classification is the orderly grouping together of those beings or things 

 that have certain characteristics in common. Correlation is the more or 

 less technical designation employed in geology for the establishment of 

 an orderly relationship between the geologic units of separate areas or 

 regions. Back of all this is the desire to establish a geologic chronology 

 or time scale — that is, a properly subordinated sequence of geologic events. 

 When such a time scale has been established for a limited area as well as 

 the perfection or the imperfection of the geologic record will permit, it 

 becomes a large and important part of the work of geology to carry that 

 record into near-by and ultimately more and more remote areas — that is, 



1 Published by permission of the Director of the United States Geological Survey. 



This paper, read at the summer meeting of the Paleontological Society held at the 

 University of California, August 3, 1915, was the concluding one in the symposium 

 entitled "General consideration of Paleontologic criteria used in determining time rela- 

 tions." 



Manuscript received by the Secretary of the Geological Society April 6, 1916. 



(525) 



