ORIGIN OF COAL FROM FUCI.

81

tation; that the beds of coals, in their extensive concavities, were immense accumulations of fuci, &c., loaded with the various animal substances that shelter among them, which were overwhelmed by vast aggerations of the loose soils of the sea in the course of its retreat, and were left for decomposition and recomposition by the chemical action of the marine fluid which they contained, and with which the enclosing and compressing soils were saturated: under which compression they had lain in course of bituminisation and mineralization, for some thousands of years before they were brought to light 'entirely dissolved and recomposed in their elements, so as to be converted into the fossil masses to which we give the name of coal.' In this class of vegetation, so circumstanced," adds our author, "it is perhaps possible, that the ingredient might yet be found, which was uniformly wanting in the carbonisation of wood of earthy growth."*

The notion, once more prevalent than at present, that the coal strata are derived from the covering up of ancient peat bogs, appears to derive no support from evidence for the analogy subsisting between certain relations in the carboniferous series, and sections of some interstratified turbaries, however it may illustrate the process by which vegetable matter becomes converted into coal, affords no indications of a common origin. For, however unreasonable it might be to expect to find the remains of any of the numerous mosses which enter into the composition of recent peat, in strata where almost every trace of the original organisation of plants presumed to have been

Penn's Comparative Estimate, vol. ii. p. 187.

G

so much better fitted to resist decomposition is obliterated, still the associate shales do frequently present us with impressions of matters scarcely, if at all, less delicate in structure. It is, moreover, judging from the present state of things, not probable that tracts of moss covered large portions of the earth at the era of the coal formation, in common with plants, the remains of which are allowed to indicate the concurrence of intertropical vegetation, but not of the bog-formations of temperate and polar regions.

That the common bituminous coal, so abundant in this country, and in the eastern Continent, as well as in some parts of North America, owes its origin to vegetable depositions of some kind, at whatever time, or under whatever circumstances these have taken place, may be said to be all but universally admitted at present. Many eminent geologists, however, are hardly yet satisfied to refer the vast mountains of matter, apparently so much farther removed from ligneous identity as the anthracite appears to be, to the same cause. To this reference they have found an objection which, to them, seems of itself insuperable, in the vast quantity of this useful mineral. But is this objection really insuperable? Does it not proceed from a limited view of the operations of nature, from a disinclination to allow sufficient time for the execution of her stupendous designs? Many errors in geological science are justly attributable to an erroneous or limited estimate of time; and yet the eloquent chronicles of inanimate nature tell us of changes in the constitution of the globe which we inhabit, for the accomplishment of which ages must have been requisite. How many years must have rolled away, after the disruption of the original rock,

before the sandstone formation attained its present. degree of compactness. Those, therefore, who deny that the anthracite is of vegetable origin, must bring forward some other objection than the want of time : and if they found their objection upon the depth and extent of this formation, we urge the analogy of the bituminous coal, and thus sustain the claim of the anthracite to a vegetable origin. It will not be denied that the power which could create mineral carbon, could also create vegetable carbon, and afterwards by some great convulsion, subject it to an irresistible force. The foregoing are the sentiments of Mr. Bunker, an American writer, whose opinions are given in Silliman's Journal. "Indeed," continues this gentleman," it seems to me more in unison with the other arrangements of Providence, that the vegetables which beautified the face of the earth, for the happiness of one race of beings, should afterwards, when those beings had passed away, be stored up for the use of other successive generations of men." But the object of Mr. Bunker's communication to the Journal above-named is not, he says, "to engage in the discussion of the question, whether anthracite coal is of vegetable origin, except so far as may be necessary in the exhibition of the testimony which I am able to produce in support of that opinion. Mr. Bakewell, in his introduction to geology, asserts, that no vegetable impressions have ever been discovered in the anthracite, and I believe that most geologists are of the same opinion. I have been so fortunate as to obtain from a small quantity of Schuylkill coal, six specimens, proving that trees were at least present when the coal was formed, if vegetable matter is not material. The best specimen

presents the longitudinal section of a piece of wood, ten inches long and two inches broad. Another specimen exhibits a similar section six inches long. A third contains a bit of wood one inch square, and one tenth of an inch in thickness, and this piece could be easily detached. Another specimen exhibits a section of wood, from four to five inches long, and about three inches in width. The grain of this piece resembles that of the oak. A fifth contains a section four inches by three. The sixth is the counterpart of the fifth the two pieces being the parts of a larger specimen, the cleft of the coal dividing the wood equally and similarly, leaving a portion in each division. These specimens exhibit not impressions merely, but real wood, resembling charcoal, although softer. In examining coal, I have often found indentations, which by the aid of the imagination, could be magnified into vegetable impressions; but I never before found real wood. About the specimens which I possess, there can be but two suppositions. Either this wood was introduced in some incomprehensible mode into the heart of the solid mass of the coal, or else it is a remnant, not wholly consolidated, of the material from which the coal was formed. I believe that the latter supposition is more philosophical, and consequently more rational than the former." *

* Silliman's American Journal, 1833.

CHAPTER V.

ORGANIC REMAINS.

Opinions of the Ancients concerning Organic Remains -Equivocal generation-Operation of plastic and forming energies-Conditions of vegetable remains -Families of plants existing at the period when the Coal beds were deposited-Plants of the upper Coal -Cycadiform fronds-Ligneous fossils of the true Coal formation-Mr. Witham's observations-Modifying causes of the variety of casts of stems discovered in different substances—Figures and descriptions-Microscopical examination of the minute structure of fossil bodies-Probability that trees of the more complicated woody structure, as well as the merely vascular and cellular kinds, existed at the period of the Coal formation-Fossil fishes-Muscles-Question of toads found alive in the Coal rocks-Hutton's observations on the traces of existing vegetable tissues in the perfect kinds of Coal.

IT

may now be interesting to advert somewhat more particularly to those phenomena which bring the coal formation into such immediate contact with the traces .or remains of organic matter: and, although it is almost entirely in the rocks subjacent to, or incumbent upon, the carboniferous strata, that we meet with