354 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mai'ch 13, 



tributary streams from the metamorpMc promontory stretching to- 

 wards Cape Porcupine, and unites with the west branch at the 

 northern margin of the granitic metamorphic band. The united 

 stream then flows through a narrow valley in the granitic group to 

 the Atlantic. 



The groups of hills of the syenitic metamorphic system forming so 

 important features in the physical geography of the eastern part of 

 this province, were for the first time dehneated with an approach to 

 .accuracy in a small geographical map compiled by the writer, and 

 published in 1847. (See Map, fig. 1.) 



Some of the facts already stated bear on the question of the rela- 

 tive figes of these metamorphic groups. That the metamorphism of 

 the granitic group is of greater antiquity than the carboniferous 

 period, is proved by the fact that the debris of its igneous and altered 

 rocks is found in the lower carboniferous conglomerates ; as, for ex- 

 ample, in the valley of the west branch of the St. Mary's River, I 

 have not found any evidence in that group of igneous action of a later 

 date. 



In like manner, at Cape Porcupine, Antigonish, MaHgnant Cove, 

 the East River of Pictou, and along the whole base of the Cobequid 

 hills, the lower carboniferous grits and conglomerates are filled with 

 the debris of the rocks of the syenitic group, on which in many 

 places they are seen to rest unconformably. The connection of this 

 group with strata containing Upper Silurian fossils, renders it probable 

 that a great part of its beds belong to the Silurian system. There is 

 also evidence that igneous and metamorphic action were continued in 

 this group during the carboniferous period. Instances of this have 

 been mentioned above, and a very interesting example, occuiTing near 

 Arisaig, has been noticed in a former paper*. This late continuance 

 or renewal of igneous action is evidently connected with the very 

 irregular distribution of those parts of the syenitic group in which it 

 has occurred. 



Assuming then that the group which I have named the syeniticy 

 consists of altered Silurian and carboniferous strata, perhaps with some 

 of Devonian age, though these have not yet been recognized, we may 

 conclude that the beds of the granitic group belong either to some of 

 the older members of the Silurian system, or to a still earlier period. 

 In the part of Nova Scotia to which this paper is restricted, I have 

 not been able to observe the actual superposition of the beds of these 

 groups on each other ; but in the western part of the province, where 

 the syenitic and granitic groups are frequently found in contact with 

 each other, it is possible that such evidence may be obtained. 



Mineral Deposits of the Syenitic Metamorphic Group. 



In a number of localities in this series, venigenous deposits of ores 

 of iron and copper have been discovered. Some of these are of eco- 

 nomical value ; and are also interesting in the associations of minerals 

 which they present, and in the inferences which may be deduced from 



* Quart. Journ. Geol. Soc, vol. i. p. 330. 



