178 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



throughout the 14,570 feet in the Nova Scotia section, there ap- 

 pears to be no trace of any substance of a marine character ; and 

 from anything exhibited in the composition of the beds, all might 

 have been deposited in fresh water. It seems infinitely impro- 

 bable, had the deposition taken place in a sea, that a series of 

 accumulations of this description, implying, be it observed, a vast 

 duration of time, with different depths and different qualities of sea- 

 bottoms, should have taken place without a trace being discoverable, 

 either upon the surface of the submerged layers of vegetable mat- 

 ter, or in any part of the clays and sandstones that lie upon them, 

 of a marine animal or plant. It seems no less improbable, that, in 

 a sea skirting a shore, there should be such an absence of agitation 

 throughout so vast a space of time, as to allow a tranquil deposit of 

 layers of fine detritus over a wide area, a spreading out of the leaves 

 of delicate plants in layers of clay and sand like the specimens in 

 a herbarium, and a gradual and insensible passage, in many in- 

 stances, from one bed into another. Great as the North American 

 lakes are, I am not prepared to say that grave objections may not 

 be urged against the probable existence of such vast bodies of 

 fresh water as would be of sufficient extent and depth to receive the 

 beds of many coal-fields ; but the absence of marine remains through- 

 out vast depths of strata in coal-fields is a remarkable fact well 

 deserving of the most careful investigation. 



That the terrestrial vegetable matter from which coal has been 

 formed has in very many instances been deposited in the sea is 

 unquestionable, from their alternations with limestones containing 

 marine remains. Such deposits and alternations in an estuary at the 

 mouth of a great river are conceivable, but whether such enormous 

 beds of limestone, with the corals and moUusks which they contain, 

 could be formed in an estuary may admit of doubt. But it is not 

 so easy to conceive the very distinct separation of the coal and the 

 stony matter, if formed of drifted materials brought into the bay by 

 a river. It has been said that the vegetable matter is brought down 

 at intervals, in freshets, in masses matted together, like the rafts in the 

 Mississippi. But there could not be masses of matted vegetable matter 

 of uniform thickness 14<,000 square miles in extent, like the Browns- 

 ville bed on the Ohio (the Pittsburg seam mentioned in page 170); 

 and freshets bring down gravel, and sand, and mud, as well as plants 

 and trees. They must occur several times a-year in every river ; 

 but many years must have elapsed during the gradual deposit of the 

 sandstones and shales that separate the seams of coal. Humboldt 

 tells us (Kosmos, p. 295) that in the forest lands of the temperate 

 zone, the carbon contained in the trees on a given surface would not 

 on an average of a hundred years form a layer over that surface 

 more than seven lines in thickness. If this be a well-ascertained 

 fact, what an enormous accumulation of vegetable matter must be 

 required to form a coal-seam of even moderate dimensions ! It is 

 extremely improbable that the vegetable matter brought down by 

 rivers could fall to the bottom of the sea in clear unmixed layers ; 

 it would form a confused mass with stones, sand and mud. Again, 



