BROWN ON THE GEOLOGY" OF CAPE BRETON. 



213 



N. E. 



George's 

 River. 



S. \V. 



8. Coal measures. 



7. Millstone grit. 



6. Mountain limestone. 



5. White marble. 



4. Conglomerates. 



3. Greywacke slates. 



2. Altered shales. 



1. Small-grained red granite. 



(Distance'8 miles.) 



At Brack's Brook, we find the greywacke slates resting upon 

 granite and porphyry, and extending to Soldier's Cove, where they 

 meet the red shales and sandstones of the millstone grit series. 

 Several small troughs of an apparently recent limestone may be 

 here observed, lying unconformably upon the greywacke. 



The conglomerate of Isle Madame seems to pass insensibly into 

 a fine-grained greywacke slate, on the south side of that island. 



Rocks of igneous origin occupy a very large proportion of the 

 island of Cape Breton ; and the Jofty table-land in the northern 

 part of the island is supposed to consist almost wholly of primary 

 rocks. The high and narrow ridge lying between St. Ann's 

 Harbour and the ship entrance of the Lake, consists of fine-grained 

 red granite and syenite ; and at George's River, a similar granite 

 protrudes through the limestone and greywacke as before-men- 

 tioned. On the south shore of East Bay, granites and porphyries of 

 various composition extend from Brack's Brook to the outcrop of 

 the mountain limestone, a distance of ten miles, forming barren 

 naked peaks, in some instances 800 feet in height. We find 

 also here a beautiful porphyry, having a dark-green base, with 

 large whitish crystals of felspar. The small island of St. Paul's, 

 which lies about twelve miles east of Cape North, in the direct 

 track of vessels bound up the St. Lawrence, and which has proved 

 fatal to many a noble ship, consists of mica slate, gneiss, and gra- 

 nitic rocks, apparently stratified in thin beds, with an E. and W. 

 strike, and nearly on their edges. 



To show the connection of the strata of Cape Breton with those 

 of Nova Scotia, I have continued the section across the Gut of 

 Canso to the shales and sandstones of Merigomish. It will be 

 seen that the conglomerates on the Nova Scotia shore, which suc- 

 ceed the greywacke and igneous rocks of Cape Porcupine, dip 

 under the sandstones and shales of Tracadie (including some 

 trifling seams of coal at Pornket), and emerge to the westward 

 from beneath the gypsiferous strata of Antigonish, reposing upon 

 and passing into the greywacke rocks of Antigonish mountain. 

 The conglomerate ags^ft sets in on the western flank of Antigonish 

 mountain, and is follow**! by the sandstones and shales of Meri- 

 gomish and Pictou. 



T 3 



