1:' 

 ( 



""hO 



NEW FACTS RESPECTING THE GEOLOGICAL RE- 

 LATIONS AND FOSSIL REiMAINS OF THE 

 SILURIAN IRON ORES OF PICTOU, 

 NOVA SCOTIA. 



By J. W. Dawson, LL.D., F.B.S. 

 (Read before the Natural History Society of Montreal, April 5tb, 18K0.) 



The subject of this paper has already been discussed by me in 

 various previous publications ; and most recently in a paper read 

 at the Portland meeting of the Association for the Advancement 

 of Science in 1 874, and published in the Journal of this Society ; 

 and in the Supplement to the second edition of" Acadian Geol- 

 ogy," 1878. In these publications I have described the general 

 ?rrangement of the Rocks of the Cobecjuid Series in the rising 

 grounds on both sides of the East Branch of the East River of 

 Pictou, the superposition on these of Upper Silurian rocks holding 

 bedded red hematite, and the occupation of the valley itself by a 

 narrovy band of Lower Carboniferous beds. 



I may explain that the name *' Cobecjuid group " was proposed 

 in my Acadian Geology, 1868, for the series of schistose and 

 crystalline rocks constituting the axis of the Cobequid hills, and 

 extending eastward from these, with some partial interruption, 

 through the hilly districts of southern Pictou, In the Cobequid 

 hills, where these rocks are well exposed, they consist of two 

 members : (1) an upper .series of gray and dark slates and 

 quartzites with a band of crystalline limestone and veins of iron 

 ores ; (2) a lower series consisting largely of felsite, porphyry 

 and agglomerate. Both series are pene ied by dykes and 

 masses of red syenite and dark-coloured diabase, the latter cutting 

 also the overlying Silurian rocks. These; last, as seen at Went- 

 worth and New Annan, overlie unconformably the Cobequid 

 group, and afford fossils characteristic elsewhere of the Upper 

 Silurian system. The least antiquity that can be assigned to 

 the Cobequid rocks is thus that of the Siluro-Cambrian ; and by 

 some, on the ground chiefly of mineral character, they have been 

 regarded as Huronian. I have ventured to suggest, on the evi- 



U ^ "^ 



