BULLETIN OF THE GEOLOGICAL SOCIETY Of AMERICA 

 Vol. 24, pp. 217-228 June 7, 1913 



POSTGLACIAL EARTH-MOVEMENTS ABOUT LAKE 

 ONTARIO AND THE SAINT LAWRENCE RIVER 1 



BY J. W. SPENCER 



(Read before the Society December 31, 1912) 



CONTENTS 



Page 



Introduction 217 



Iroquois water north of the Adirondack^ 218 



Iroquois shore and higher terraces in the Mohawk Valley 219 



Features of the country north of the Adirondacks 220 



Triangulation of the earth-movements recorded in the beaches 221 



Iroquois plane in the region of Covey Hill 224 



Deformation observed in the marine beds at Montreal 225 



Present stability of, the Lake region 226 



Results s 227 



Introduction 



The maximum amount of deformation and direction of the post- 

 glacial earth-movements was first discussed by me in a memoir entitled 

 "The Iroquois Beach : a chapter in the geological history of Lake On- 

 tario." 2 In this I made, the following statement : 



"If the axes of maximum elevation for the various triangles about Lake 

 Ontario and Georgian Bay be produced, they meet near latitude 51° north and 

 longitude 74%° west, a few miles west of Lake Mistassini, and east of the 

 southern end of James Bay # 



"Although mainly radiating from the focus, the axes of maximum elevation 

 for the different triangles is not uniform, and are locally modified, as along 

 the western side of Lake Ontario, where there is found a secondary axis of 

 uplift to the east. Combining the more western axes with those of the eastern 

 end of the lake, another focus of uplift appears near the 'height of land' be- 

 tween Lake Ontario and Hudson Bay, in about latitude 48° north and longi- 

 tude 76° west. From the double foci, it may be inferred that the uplift. 



1 Manuscript received by the Secretary of the Society March 8, 1918. 

 3 Trans. Royal Society of Canada, vol. vii. sec. iv. p. 129; read Maj :.. L880. Bee also 

 Journal of Geology, vol. xix, 1911, pp. 57-60. 



(217) 



