618 THE LOWER SILURIAN PERIOD. 



S.S.E., and give no evidence that this metamorphic district has suf- 

 fered any considerable disturbance since their deposition. At Mahone 

 Bay, however, I observed a large quantity of fragments of reddish 

 amygdaloidal trap, which cannot be far from their original site, and 

 probably belong to some trappean eruption of the Carboniferous 

 period. 



Aspatogoen, which is a rocky promontory, about 500 feet in height, 

 separating Mahone from Margaret's Bay, consists, according to 

 Mr Poole, principally of quartzite and slate with gi'anite, and is 

 apparently at the extremity of a thick dike or ridge of the latter 

 rock, extending to the northward across the stratification of the 

 country. It is the highest land on the Atlantic coast of Nova Scotia. 



Margaret's Bay is another deep indentation, between Aspatogoen 

 and a broader but lower tract of granitic rock, extending to the north- 

 west arm of Halifax Harbour. Around Margaret's Bay, as at 

 Chester, there are small patches of Lower Carboniferous rocks ; but 

 these are for the most part concealed under granitic debris drifted 

 from the neighbouring districts. 



The granitic district east of Margaret's Bay, and terminating at 

 Cape Sambro, has a north and south direction. It contains several 

 varieties of common and porphyritic gi'anite, with veins of coarse- 

 grained, and more rarely of graphic granite. Near the north-west 

 arm there are good opportunities of observing its junction with the 

 slates which succeed it to the eastward. The slate is not here con- 

 verted into mica-slate ; but, in the vicinity of the gi-anite, it is hardened 

 and rendered crystalline, and in some places passes into a rock re- 

 sembling hornblende slate. In other places it appears as a hard 

 flinty slate, filled with slender prismatic crystals apparently of stauro- 

 tide. In close contact with the granite the slates assume the appear- 

 ance of gneiss, and are traversed by granite veins, which often contain 

 crystals of schorl and garnet, indicating that these veins received 

 additions of foreign substances, as boracic acid, iron, etc., in passing 

 through the stratified rocks. The granite itself is here porphyritic, 

 and occasionally contains fragments of the rocks through which it has 

 passed, fused into gneiss and mica slate. All these appearances 

 indicate that the intensely heated and molten granite was the cause 

 of the alteration of the slates. 



Eastward of Halifax, the whole country as far as Musquodoboit 

 River, and northward to the northern limits of this district, consists 

 principally of alternate thick beds of coarse clay slate, often highly 

 pyritous, and quartzite, granite bosses projecting through it in a few 

 places. The strike of the beds in this part of the province approaches 



