BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 32, pp. 353-358 SEPTEMBER 1, 1921 



PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



CEITEIUA ¥011 DETEKMINATION OF CLIMATE BY MEANS 

 OF FOSSIL PLANTS 1 



BY F. H. KNOWLTON ^ 



{Read before tlie Paleontological Society December 29, 1920) 



CONTENTS 



Page 

 Introduction 353 



Stabilization of temperatures for plants and animals 354 



Criteria for interpi-etation of climatic conditions 355 



Steps in study of climatic criteria • 357 



Examples of the application of climatic criteria 357 



Inteoduction 



After some differences in concept, the term climate lias come to be 

 applied to the atmospheric conditions of weather normal to a given lo- 

 cality or region. Although there are very considerable areas of the earth's 

 surface that exhibit similar climatic conditions, it needs little reflection 

 to demonstrate that the climate of the earth at the present day is by no 

 means uniform throughout. If, for instance, we travel either north or 

 south from the equator we pass successively through a so-called torrid 

 zone, a temperate zone, and, in polar lands, a frigid zone, each with minor 

 but distinctive modifications. In other words, the present distribution 

 of climate is zonal. But it has been demonstrated with what seems a 

 reasonable degree of certainty that the climates of the past were distinctly 

 lion-zonal in their distribution — that is, ancient climates appear to have 

 been practically uniform for vast periods of time and of practically world- 

 Avide extent. The object of the present paper is to set forth the criteria 

 by which this conclusion is reached. 



1 Manuscript received by the Secretary of the Society March 3, 1921. 

 This paper is one of a series composing a "Symposium on criteria and methods em- 

 ployed in paleontological research." 

 - Read by R. S. Bassler. 



(353) 



