i88r. 71 Trans. JV. V. Ac. Set. 



The following paper was read by Prof. H. L. Fairchild : 



ON A PECULIAR COAL-LIKE TRANSFORMATION OF PEAT, RECENTLY 

 DISCOVERED AT SCRANTON, PENN. 



The material which we shall notice this evening has naturally been 

 regarded, on account of its associations, as illustrating in some degree 

 the formation of coal. A brief description of that alteration of peat 

 which has resulted in the formation of coal, is therefore desirable. 



Peat results from decomposition of vegetable matter under water. 

 The latter excludes the atmosphere and largely prevents the oxidation, 

 which removes the vegetable debris on the upland, and which if rapid 

 we call combustion, or if slow, decay. In northern regions peat-swamp 

 vegetation is commonly a sort of moss (Sphagnum) which grows upward 

 as it dies below. Great peat deposits are also produced in lower 

 latitudes from the debris of forest trees. The great Dismal Swamp is 

 a fine example, and in the Hackensack and Newark meadows we have 

 examples of peat-formations of great depth, produced by the slow 

 subsidence of the region and the accumulation of salt-marsh vege- 

 tation. 



In former geological age=, immense peat deposits were produced in 

 the vast lowlands along the borders of the continents, or at the deltas 

 of the ancient rivers. These great swamps were frequently submerged 

 in the sea and deeply buried beneath mud and sand. This event occur- 

 red perhaps many times in a single locality. The buried peat slowly 

 decomposed. Much of the hydrogen and oxygen of the vegetable 

 tissue, and some of the carbon, were eliminated. The remainder was 

 consolidated by the weight of the superincumbent strata, and the 

 result is bituminous coal. Thus we have the six to twenty coal beds ot 

 Pennsylvania, or the one hundred coal-seams of Nova Scotia. 



The evidence that our coals are primarily formed in this manner is 

 abundant, clear and incontrovertible. Few subjects are by our induc- 

 tive science more definitely settled than this. We find these buried 

 vegetable deposits in every stage of decomposition and alteration. 

 Where the containing rocks are undisturbed, lying in their original 

 positions, the coal contains a large proportion of volatile matter, and 

 is bituminous. But where the rocks are dislocated and lolded the coal 

 is, by the pressure and heat, changed to anthracite or perhaps to 

 graphite. The proportion of fixed carbon, or the degree of alteration, 

 is always proportionate to the amount ot disturbance which the asso- 

 ciated rocks have suffered. Hence anthracite coal is a metamorphosed 

 coal, just as marble is metamorphosed limestone, or quartzyte is meta- 

 morphosed sandstone. The metamorphism of coal is still going on. 

 The escape of the volatile matter, in which the change consists, is 



