Bivalve Shells of Nova Scotia. 133 



Such were undoubtedly the conditions of coal accumula- 

 tion; but we must be prepared to admit many exceptional 

 cases. Yast areas of bog imply great tracts of water- 

 soaked and inundated ground, filling up with drifted vege- 

 table muck. They also necessitate such casualities as 

 bursting of bogs and the floatage of their semi-fluid contents 

 over large areas, as we find now occasionally occurring in 

 Ireland and in Florida. To such causes we may attribute 

 beds of earthy bitumen and of cannel coal, and possibly the 

 coal containing fish scales which I have described in the 

 Joggins section l or the celebrated Jarrow coal in Ireland, 

 recently so well described by Mr. Bolton 2 in which fossil 

 fishes and batrachians occur imbedded entire in the coal 

 itself, as if they had been overwhelmed and buried in a tor- 

 rent of vegetable mud. The Jarrow coal is also, over a 

 large part of its area, destitute of an underclay or "seating" 

 as it is called in Ireland, and it thins out in different direc- 

 tions, as if it had been formed in a limited depression of the 

 surface. Such beds constitute the exception which illus- 

 trates if it does not prove the rule, by showing how different 

 our ordinary coal beds must have been had they been 

 formed in such special and peculiar ways. 



It is further to be observed that while in many places 

 the coal-formation swamps have been elevated into uplands 

 and mountains, in other regions they have been depressed 

 beneath the sea. The island of Cape Breton affords an 

 excellent example of this. It consists of two broad ridges 

 of old Palaeozoic and Pre-Cambrian rocks with a carbon- 

 iferous depression in the middle, and belts and patches of 

 coal-formation beds around its sides, dipping towards the 

 sea. The soundings show that these coal-formation areas 

 are continuous under the sea with those of Nova Scotia 

 proper on the South and Newfoundland on the North, and 

 that they extend to great distances under the Atlantic to 

 the East and the Gulf of St. Lawrence to the West. Thus 

 we can imagine Cape Breton in the coal-formation period 



1 Acadian Geology, pp. 164, 199. 



- Manchester Transactions, Vol. XXII, Part 16, 1894. 



10 



