ATLANTIC COAST OF NOVA SCOTIA. 615 



colour. In the coast metamorphic district of Nova Scotia, it appears 

 in many and beautiful varieties. Talcose, chloritic, and hornblendic 

 slates are comparatively rare in this district. 



4. Quartz rock, or Quartzite, consisting of grains of flinty sand 

 fused together, and with occasionally a little mica, occurs in this series 

 in very massive beds, 



5. Clay slate, or argillaceous slate, abounds, and is usually in this 

 district of gray and black colours, and varying very much in texture 

 and hardness. It often presents indications of the original bedding 

 in different planes from those of the lamination, the latter being an 

 effect of causes acting at a time posterior to the original deposition, 

 and, as ali-eady stated, pressure was probably the most efficient of 

 these causes. 



Between these rocks there are many intermediate forms. Granite 

 often passes by imperceptible gradations into gneiss — -this into mica 

 slate — this into quartzite — and this into coarse or flinty clay slates. 

 There appears every reason to believe that all these rocks, except the 

 granite, are merely variously metamorphosed forms of common sand- 

 stones and clays. 



The Lower Silurian rocks form a continuous belt along the Atlantic 

 coast of the province, narrow at its north-eastern extremity, and at- 

 taining its greatest development in the western counties. Its southern 

 or coast side has a general direction of S. 68° W. ; its inland side, 

 though presenting some broad undulations, has a general direction of 

 about S. 80° W. Its extreme breadth at Cape Canseau, its north- 

 eastern extremity, where it is bounded on one side by the ocean, and 

 on the other by Chedabucto Bay, is only about eight miles. In its 

 extension westward, it gradually increases in width, luitil at the head 

 of the west branch of the St Mary's River, eighty miles distant from 

 Cape Canseau, it is about thirty miles in breadth. In the western 

 counties it again increases in width, and though its northern boundary 

 is not well ascertained, its breadth can scarcely be less than fifty miles. 

 Its total length is 250 miles. 



The general character of the geology of this district may be very 

 shortly stated. It consists of thick bands of slate and quartzite, having 

 a general N.E. and S.W. strike, and highly inclined. In several places 

 large masses of granite project through these rocks, and in their vicinity 

 the quartz rock and clay slate arc usually replaced by gneiss and mica 

 slate, or other rocks more highly metamorphosed than usual. liearing 

 in mind this general character, wo may proceed along this district from 

 west to cast, noting the more interesting points of its structure as they 

 occur. 



