﻿314 Canadian Record of Science. 



should be stated. The investigations in this quarter 

 have now been carried on for six years, and have extended 

 over a very large area to the north of the Ottawa, in 

 which is included the typical Grenville series of Sir W. E. 

 Logan, and extending far up the Gatineau Eiver ; while to 

 the westward, the work has been carried on till the 

 vicinity of the area, described in the accompanying paper, 

 has been reached. It may be said therefore that the 

 detailed examination of the rocks which make up the 

 Grenville and Hastings series has extended over an area 

 about 250 miles in length by 75 miles in breadth. 



In the early days of the study of these rocks much 

 difficulty was experienced. Firstly there was a great and 

 almost inaccessible wilderness, the only available means 

 of travel over the greater portion being by canoes ; and in 

 the second place there was an almost entire lack of 

 trained observers to carry on the work. Add to this the 

 entire absence of microscopical determinations, and one 

 can readily comprehend the difficulty experienced in the 

 attempt to solve this most difficult of the problems in 

 Canadian geology. 



Foliation and stratification were considered conclusive 

 evidence of sedimentation, and as most of the rocks of the 

 great Laurentian complex gave evidence of these forms of 

 structure, the inference naturally followed that the greater 

 portion of the gneissic, granitic and anorthositic rocks 

 were of sedimentary origin. So far was this sedimentary 

 theory carried out that, in the earlier reports of the 

 Geological Survey, even the masses of binary granite and 

 many of the pyroxenic rocks were included in the same 

 category. This was at the time a very natural con- 

 clusion, since many of these masses have a regular bedded 

 structure and conform, over very considerable areas, 

 to the regular stratification of the rocks, either gneiss or 

 crystalline limestone. As the country became more 

 accessible the field investigations showed very clearly 



