BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 1, pp. 163-174 March 12, 1890 



NOTE ON THE PRE-PALEOZOIC SURFACE OF THE ARCHEAN 



TERRANES OF CANADA. 



BY ANDREW C. LAWSON, PH. D. 



[Read before the Society December 27, 1889.) 



CONTENTS. 



Page 



Introductory Eemarks 103 



The Phenomena in Central Canada 164 



Contacts between the Animikie and the Archean 1G4 



Contacts between the Nipigon and Older Rocks 166 



The Phenomena in Eastern Canada 167 



Contacts between the Paleozoic and the Archean.... 167 



Review of the Evidence 169 



General Considerations 169 



Former Extension of the Paleozoic 169 



Transgressions and Oscillations in Level .— 171 



The Erosion of the Archean 172 



Source of Paleozoic Sediments 172 



Discussion 173 



Introductory Remarks. 



Since the establishment of the glacial theory the cause of the hummocky 

 and roches moutonnees character of the rocky surface of the Archean terranes 

 of North America has generally been ascribed to the action of the ice of the 

 glacial epoch. Two opinions have been prevalent, having this belief as their 

 basis. The first and older view was, in accordance with the theories pro- 

 mulgated by the Scotch geologists, that the hummocks and their complemen- 

 tary hollows were produced by the direct plowing or gouging action of glacier 

 ice loaded with rock debris. The second and more modern view is, that just 

 as south of the terminal moraine we find the crystalline rocks extensively 

 decomposed in situ, so prior to the advent of the glacial epoch the Archean 

 terranes of the north were similarly decomposed, and the present hummocky 



XXII— Bull. Geol. Soc. Am., Vol. 1, 1889. (163) 



