244 THE GROWTH OF COAL 



I have had reference principally to my own observations in the 

 coal formation of Nova Scotia; but similar facts have been 

 detailed by many other observers in other districts. 1 



A curious point in connection with the origin of coal is the 

 question how could vegetable matter be accumulated in such 

 a pure condition There is less difficulty in regard to this if 

 we consider the coal as a swamp accumulation in situ. It is 

 in this way that the purest vegetable accumulations take place 

 at present, whereas in lakes and at the mouths of rivers vege- 

 table matter is always mixed up with mud. Coal swamps, 

 however, must have been liable to submergences or to tem- 

 porary inundations, and it is no doubt to these that we have to 

 attribute the partings of argillaceous matter often found in coal 

 beds, as well as the occasional gulches cut into the coal and 

 filled with sand and lenticular masses of earthy matter. To a 

 similar cause we must also attribute the association of cannel 

 with ordinary coal. The cannel is really a pulpy, macerate 

 mass of vegetable matter accumulated in still water, surrounded 

 and perhaps filled with growing aquatic herbage. Hence it is 

 in such beds that we find the greatest accumulations of macro- 

 spores, derived, probably, in great part from aquatic plants. 

 Buckland long ago compared the matter of cannel to the 

 semifluid discharge of a bursting bog, and Alex. Agassiz has 

 more recently shown that in times of flood the vegetable muck 

 of the Everglades of Florida flows out in thick inky streams, 

 and may form large beds of vegetable matter having the 

 character of the materials of cannel. It is evident that in 

 swamps of so great extent as those of the coal formation, there 

 must have been shallow lakes and ponds, and wide sluggish 

 streams, forming areas for the accumulation of vegetable debris 

 and this readily accounts for the association of ordinary beds 

 of coal with those of cannel, and with bituminous shales or 



1 Especially Brongniart, Goeppert, Hawkshaw, Lyell, Logan, De la 

 Boche, Beaumont, Binney, Rogers, Lesquereux, Williamson, Grand' Em v. 



