[blls] the ARCH^AN of EASTERN CANADA 123 



ish and Guysborough, they are largely felsitic and syenitic in character, 

 with considerable areas of diorite, but there is only a small development 

 ■of the crystalline limestones. In certain of the calcareous strata, how- 

 ■ever, serpentinous bands occur in which an Eozoonal structure is appar- 

 -ent. In the adjacent island of Cape Breton their development is much 

 more extensive. Felsitic and syenitic rocks are, however, the most abun- 

 dant, and make up the great bulk of thePre-Cambrian, both to the north 

 nnd south of the Bras d'Or lakes ; but at a number of places in the 

 northern prolongation of the island, areas of crystalline limestone are 

 seen, which are associated with syenites, quartzites, felsites, greenstones 

 îind schists of various kinds, the series in this respect resembling very 

 closely much of the great Archican complex, as seen in the Hastings series 

 of Ontario and the Grenville series of Quebec. Yery full descriptions of 

 these rocks have been given by Mr. Hugh Fletcher in the reports of the 

 Geological Survey. Following the determinations, as adopted in the pro- 

 vinces to the west, they have been classed partly as Laurentian and partly 

 as Huronian. In their lithogical aspect they also very closely resemble 

 the rocks of the several divisions of the Pre-Cambrian of southern New 

 Brunswick, including both the Laurentian and Huronian of that province. 



As in the case of the Laurentian of the Ottawa district, portions of 

 the granite and syenite rocks are probably more recent than the lime- 

 stones with which they are associated, and which in places overlie the 

 granitic masses, but which are also sometimes penetrated and altered as 

 if by the action of igneous intrusions. As a whole, however, the great 

 mass of the Archa-an of this portion of the province appears to more 

 «losely resemble what has been regarded as the u^^per member of the 

 Archsean of the west, which is apparently more nearly related to the 

 Huronian than to the Laurentian proper. 



In Cape Breton their Pre-Cambrian age is determined, as in New 

 Brunswick, by the fact that they are overlain at different points by fos- 

 «iliferous sediments of Cambrian age, but the areas west of the Strait of 

 Oanso appear to be suirounded by metamorphic sediments, which belong 

 To the horizon of the Cambro-Silui'ian and Devonian rather than to the 

 Cambrian, so that the Pre-Cambrian age of most of these felsitic and 

 «yenitic rocks is here not so well established as in the case of the areas 

 further to the east. 



A careful review of the evidence relating to the distribution of the 

 Archîean rocks of eastern Canada, therefore, leads one to the inference 

 that the greater portion of these, as developed east of the St. Lawrence, 

 differs in character somewhat from the great mass of the Laurentian 

 complex, which occupies so large a portion of northern Canada, and that, 

 as a whole, these are presumabl}' somewhat more recent in age. There 

 is a manifest similarity in all the areas throughout eastern Canada, in this 

 respect, that there is in every one a marked predominance of schists and 

 felspathic rocks, with a small development of the so-called Laurentian 



