VOLUME XXIV NUMBER 7 



THE 



JOURNAL OF GEOLOGY 



OCTOBER-NOVEMBER igi6 



THE GENESIS OF LAKE AGASSIZ: 1 A CONFIRMATION 



W. A. JOHNSTON 

 Canada Geological Survey, Ottawa, Canada 



CONTENTS 



Introduction 625 



Upham's Conception op the Life-History of Lake Agassiz 626 



Difficulties in Accepting Upham's Interpretation 627 



Records of Lake Agassiz in Rainy River-Lake of the Woods Dis- 

 trict 629 



Geographical Relations of the Districi 629 



Till Sheets 630 



Laminated Stony Clays 630 



• Deposits of Lake Agassiz 631 



Unconformity at the Base of Lake Agassiz Sediments 632 



Bearing of the Life -History of Lake Agassiz on the Question of 



the chabacter and cause of the differential uplift 636 



Summary 638 



INTRODUCTION 



In a paper published in the Journal of Geology in 1896, J. B . 

 Tyrrell stated that the results of his field work in the region lying 

 to the west and southwest of Hudson Bay showed that — 

 the Keewatin glacier seems to have retired northward well into Manitoba and 

 possibly even beyond the northern limit of that province before it was joined 

 by the eastern glacier. When they united the water was ponded between the 



1 Published by permission of the Director of the Geological Survey of Canada. 

 Vol. XXIV, No. 7 • 625 



