16 GEOLOGICAL MEMOIRS. 



decisively proved, what pre\iously was only conjectured, that the coal 

 itself contains plants similar to those found in the shales and sand- 

 stones above and below. The plants entombed in the latter could 

 not combine to form beds of coal, because where much sand and clay- 

 were brought down with the water, too much earthy matter was in 

 consequence mixed with the vegetable remains. 



Even in the coal which is apparently without structure, we are able 

 to find evidence of its vegetable origin, by the process which I first 

 pointed out, of examuiing the ashes left by burning. In these ashes 

 we find the well-preserved skeletons of vegetable cells, and thus obtain 

 arguments triumphantly to refute the opinion of the inorganic origin 

 of coal, which has recently been again maintained. 



These inundations, as I first proved by evidence, spared no part of 

 the vegetation, but generally uprooted and overturned all the trees, 

 such as the Calamites, Lycopodiaceee, Sigillariee and Stigmarise, which, 

 notwithstanding their great length and size, did not consist internally 

 of concentric layers of wood formed of tolerably compact vessels. A 

 few only retained their natural upright position. In consequence of 

 the high temperature of the climate, which we may well estimate at 

 20° to 25° {^1'' to 88° F.) on the average, these plants soon fell mto a 

 kind of decomposition, which continued sufficiently long to destroy en- 

 tirely the cells and vessels in the iuterior, but in many places at least 

 did not extend its influence to the bark, and in general did not result in 

 an entire decay or dissolution, but was checked in its progress by the 

 withdrawal of the influence of the atmosphere. At this stage, how- 

 ever, the Coniferse or Araucarise, foraied of remarkably dense wood, 

 though buried at the same time with the former plants, had not pro- 

 ceeded so far towards decomposition, and hence could not combine with 

 them in an uniform mass. The connection of the wood was indeed 

 already destroyed, so that it floated about in innumerable delicately mi- 

 nute pieces and fragments, which settling down amidst the more uni- 

 form mass, formed the, so-called, mineral wood-coal or fibrous-coal of 

 the mineralogists. We find a proof of the correctness of this opinion, in 

 the well-preserved structure, similar to that of the existing Araucariae, 

 which is always met with in the remarkable variety of coal, separated 

 by mineralogists under the above name from the other kinds, and 

 strongly characterized by its external aspect, its fibrous structure and 

 soiling properties. The longer or shorter coutinuance of this process 

 of decomposition, — which, judging from experiments we have instituted 

 on the decomposition of large trunks ofmonocotyledons,might readily, 

 at a temperature of 25° to 30°^ (88° to 100°F.),be completed in a single 

 summer, — the deeper or shallower layer of water which covered them, 

 and thus allowed of a more or less powerful influence of the atmosphere; 

 — and the calm or disturbed state of the surface of the w^aters, are all 

 elements, which admit of infinite modifications, and by which the no 

 less innumerable diversities in the external aspect, the state of pre- 

 servation and the contents of the stone-coal in the various regions of 

 the earth have been produced. ^\Tiere the prolonged continuance of 

 the period of decomposition, and the free unchecked access of the 



