THE 



JOURNAL OF GEOLOGY 



JANUARY-FEBRUARY, igu 



CLIMATE AND PHYSICAL CONDITIONS OF THE 

 KEEWATIN 



A. P. COLEMAN, 

 Toronto 



CONTENTS 



Introduction 



The Keewatin Eruptive s 



Keewatin Sediments 



The Iron Formation in Ontario 



Relations of the Keewatin to the Grenville Series 



Conclusions 



INTRODUCTION 



It is intended in this paper to bring together evidence which 

 has been accumulating during recent years as to the climate and 

 general physical conditions of the Keewatin. Most of this evi- 

 dence has to do with the sedimentary rocks of this age in western 

 and northern Ontario, and a considerable part of it has been 

 obtained by myself and my assistants in mapping the iron ranges 

 of the province for the Bureau of Mines of Ontario. 



Not long ago the pre-Cambrian as a whole was looked on as a 

 geological ''no man's land," full of doubt and difficulty because 

 of the obscurity of its relations. Now, however, the succession 

 as far as the base of the Huronian has been worked out in detail 

 in several areas of the pre-Cambrian in America; and we find that 

 the source of these rocks and their general relations are entirely 



Vol. XIX, No i i 



