PAGE. 



Annotated guide (continued) 46 



Geology in the vicinity of Bancroft 48 



Annotated guide (continued) 52 



The nepheline-syenite granite intrusion in the 



central part of the township of Monmouth . 55 

 Nepheline syenite intrusion in the western part 



of the township of Monmouth 58 



Annotated guide (continued) 63 



Contact phenomena in the vicinity of Maxwell's 



Crossing 63 



Geology in the vicinity of Gooderham 73 



Annotated guide (continued) 77 



The occurrence of dungannonite 79 



Annotated guide (continued) 87 



Geology in the vicinity of Craigmont 88 



Annotated guide (continued) 



References 97 



INTRODUCTION. 



This excursion has been arranged to enable members 

 of the Twelfth International Geological Congress to see a 

 typical Pre-Cambrian area in Eastern Canada. 



Like other parts of the Canadian Shield, this area is 

 strikingly different in physiographic character from the 

 great Paleozoic plain which lies to the south and west. 

 It is a rough and rugged country, supporting a more or 

 less scattered farming population, but still largely forest- 

 clad, especially in its northern portion. The Pre-Cambrian 

 in this portion of Central Ontario probably presents a 

 greater variety of rock types than has yet been described 

 from any similar area of ancient cyrstalline rocks in 

 North America. It shows in a striking manner the pro- 

 gressive metamorphism of the Grenville-Hastings series 

 resulting from Laurentian batholithic intrusions. These 

 limestones, together with their associated paragneisses 

 and amphibolites — the Grenville-Hastings series — are re- 

 garded as the greatest accumulation of Pre-Cambrian 

 sediments in North America. 



This area also contains a very extensive and remark- 

 able development of nepheline rocks, among which are 

 many rare and some unique types. These present, in places, 



