No. 5.] J. W. DAWSON — SILURIAN FOSSILS. 333 



dence of their relations to the Upper Silurian beds, and to the 

 apparently older Cambrian series of the Atlantic coast, that they 

 may be representatives of the Skiddaw and Borrowdale series of 

 England, and of the Quebec group of the Lower St. Lawrence. 



These rocks, in their extension into Pictou County, present 

 characters not dissimilar from those seen in the Cobequids. On 

 the high ground on the west side of the east branch of the East 

 River, they consist of thick beds of gray and dark slate and 

 quartzite, having a general strike of N. 20*^ to 30^ W., and with 

 very high dips to the S.W. They include a great vein of specular 

 iron ore, associated with magnetite, ankerite, and limonite, of the 

 same character with that so well known on the south side of the 

 Cobequids in Londonderry. 



The river valley, which not improbably occupies an ancient 

 line of fracture, presents a narrow trough of Lower Carboniferous 

 rocks, containing limestone and gypsum ; and at the junction of 

 these Carboniferous beds with the older rocks, on the east side 

 of the river, there is a fissure vein, filled with limonite, and in 

 some places attaining to large dimensions. 



The hills on the east side of the river consist largely of hard 

 gray slates, nacreous slates, obscure diorites, agglomerate and 

 felsite, with syenitic dykes and masses. They correspond very 

 nearly in mineral character with the Lower Cobequid series, 

 and though rudely parallel to the slates on the opposite side of 

 the river, they have so suffered from fractures and unequal denu- 

 dation that they present a very irregular surface, in the depres- 

 sions of which are the Upper Silurian hematites and their asso- 

 ciated beds ; and these rocks also succeed those of the Cobequid 

 series to the north-eastward, forming a long line of outcrop 

 extending from the East River of Pictou towards Arisaig. Thus 

 the general geological character of the region is similar to that 

 of the Cobequid hills, though locally more irregular and with 

 larger areas of Upper Silurian beds. 



So far the structure of the district has been pretty well known 

 for some time, but its somewhat complex details have been little 

 worked out, except in connection with the tracing of the iron 

 deposits, in which some explorations have been made, more espe- 

 cially by Dr. G. M. Dawson, Mr. Gilpin, and the writer. For 

 several years the principal iron properties have been under the 

 care of E. Gilpin, Esq., F.G.S., now Inspector of Mines 

 for Nova Scotia, aud his surveys have thrown much light on the 



