BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 25, pp. 205-214 June 18, 1914 



AGE OF THE DON EIVER GLACIAL DEPOSITS, TORONTO, 



ONTARIO ^ 



BY G. Frederick: wright 



{Presented by title before the Society January 1, 191J/-) 



CONTENTS 



Page 



Introduction 205 



Statement of facts as to date and duration of Lake Warren 205 



Age of Lake Iroquois 207 



Origin of the warm species of plants and animals in the Don beds. 210 



The Labrador later than the Keewatin glacier 212 



Summary 213 



Introduction 



After a preliminary statement of the main facts, the discussion in this 

 paper will relate (1) to the age of the latest glacial deposits at Toronto 

 connected with the existence of the glacial Lake Iroquois, and (3) to the 

 earliest interglacial deposits containing animals and plants which are 

 characteristic of a warmer climate than that which prevails even now 

 north of Lake Ontario. 



Statement of Facts as to Date and Duration of Lake Warren 



The occurrence of warm species of plants and animals in interglacial 

 deposits in the Don River Valley, near Toronto, Ontario, seems at first 

 sight an absolute demonstration of an immense interval of time between 

 the two invasions of glacial ice which are there clearly indicated. Briefly 

 stated, the facts are that in the valley of the Don River and at Scarboro 

 heights "near Toronto there is at the base a deposit of till which, after 

 having been extensively eroded, was covered by sedimentary deposits of 

 glacial origin 150 feet in thickness which had been brought into standing 

 water by the stream to form a delta whose base extended 25 or 30 miles 

 along the shore. The lower strata of this delta deposit are 35 feet below 

 the present level of the lake and probably at about the same relative level 



1 Manuscript received by the Secretary of the Society February 17, 1914. 

 XV— Bull. Gbol. See. Am., Vol. 25, 1913 (205) 



