204 GEOLOGY. 



The eastern provinces of Canada. — At various points in eastern Ontario, in 

 the province of Quebec, in New Brunswick, Nova Scotia, and Newfoundland, 

 the Proterozoic systems of rocks are represented. In the eastern townships of 

 Canada, there appear to be three series of pre-Cambrian rocks, some of which are 

 certainly Proterozoic. Their relations, however, have not been fully determined. 

 Proterozoic rocks occur in New Brunswick, and in the southern part of this prov- 

 ince there appear to be at least two unconformable series of them. In Nova 

 Scotia, the Proterozoic system seems to be represented by about 15,000 feet of 

 sedimentary rocks. In Newfoundland there is a pre-Cambrian sedimentary 

 series about 10,000 feet in thickness which is probably Proterozoic. In most 

 of this eastern region, the work has not been sufficiently detailed to establish 

 definitely the relations of the Proterozoic and the Archean, or even to demon- 

 strate the presence of the latter. In some places the Proterozoic formations 

 are highly metamorphic, and in others they have suffered little change since 

 induration. 



The original Laurentian area. — In the area where the name Laurentian was 

 first applied, the area north of the Ottawa and St. Lawrence Rivers between 

 the cities of Montreal and Ottawa, there is a series (the Grenville series) of highly 

 metamorphic rocks, formerly known as the Upper Laurentian. The rocks of the 

 series have been so profoundly metamorphosed that all traces of their original 

 structure are lost, but their composition and general relations leave little doubt 

 that they orginally consisted of sedimentary beds and igneous rocks. 1 Their 

 age is not established, but they are tentatively referred to the early Proterozoic, 

 Nowhere does a series of rocks better illustrate the effect of dynamic metamor- 

 phism. Not only were the rocks closely folded and subjected to all the changes 

 which accompany close folding, but along certain planes they were crushed to 

 fragments, and by movements along these planes the resistant fragments were 

 rounded so as to resemble pebbles. Thus arose layers resembling conglomerates. 

 On re-cementation, such rocks are called autoclastic. In many cases the pebbles 

 were subsequently flattened by the intense pressure to which they were sub- 

 jected. The Proterozoic of this district, so far as known, consists of but one series, 

 on which the Cambrian rests unconformably. 



In the Hastings district, southwest of Ottawa, there is a Proterozoic series 

 similar to that of the original Laurentian area, except that the rocks are less 

 highly metamorphic. They overlie the Archean unconformably. 



The rocks of Canada here classed as Proterozoic are known in dif- 

 ferent regions by different names. To them the terms Cambrian, 

 Huronian, Grenville, and Upper Laurentian have been applied at one 

 time and another in different parts of the Dominion. From this region 

 it has often been reported that they are conformable on the Archean, 

 instead of unconformable; but where detailed work has been carried 



1 Adams, Am. Jour. Sci., Vol. L, 1895, pp. 58-69; and Vol. Ill, 1897, pp. 173-180; 

 also Trans. Roy. Soc. Canada, 1899 and 1901. 



