478 PALEONTOLOGY OF ILLINOIS. 



MODE OF PRESERVATION OF VEGETABLE REMAINS IN 

 OUR AMERICAN COAL MEASURES, 



IST. REMAINS OF PLANTS IN COAL. 



It has been erroneously asserted that the coal itself does not contain any re- 

 cognizable vegetable remains, it being merely a mass of bitumen, independent 

 of any of the plants which are found in the shales overlaying or underlaying 

 it. Our bituminous coal is generally a compound of supposed layers of crys- 

 talline matter, about one eighth of an inch in thickness, separated by a thin 

 coat of pulverulent coal, or mineral charcoal, which is a mere compound of cel- 

 lular tissue and of vessels of plants. (2) 



Generally, this agglomeration of broken tissue preserves some outline by 

 which the genera, even the species to which the remains belong, can be recog- 

 nized at first sight : leaflets of ferns, stems of Calamites, bark of Stigmaria, 

 Lepidodendron, etc. But besides this, the coal itself, though more rarely, is 

 marked with distinct prints of the plants of which it is a compound. This 

 case is especially observable in a kind of hard, laminated, flint coal, obtained in 

 Mercer county by Mr. H. A. Green, which bears on the horizontal surface of 

 its crystalline lamellae, however thin they maybe cut, the outline and nervation 

 of leaves and branches of ferns, and other vegetables of the coal ; and these 

 are so distinctly marked, that the most delicate parts are as easily identified 

 as those of plants preserved in shales. 



The great abundance of these remains show that the whole mass of this coal, 

 which is true coal and burns freely, is a compound of them. In the cannel 

 coal which has been formed under water from more decomposed vegetables, 

 the forms are more rarely recognizable. Yet the cannel coal of Breckenridge, 

 Ky., is marked through its whole mass by stems and leaves of Stigmaria and 

 Lepidodendron, rendered distinct by infiltration of sulphuret of iron. Even 

 in the anthracite coal of Penna., whose matter has been subjected to heat and 



(2) This fact is easily ascertained by microscopical examination. Prof. J. W. Dawson, of 

 Montreal, has closely examined this charcoal, and published, as results of his interesting re- 

 searches, numerous forms of vessels of plants. The same kind of researches had been 

 already pursued by Prof. Goppert, who had recognized, in this pulverulent coal, remains of 

 plants of every family hitherto kuown to occur fossil in the eoal. (Quat. Geol. Jour., vol. 5,' 

 mem., p. 17.) 



