more than at the total extinction of some of their species, in either element. On the contrary, what our strata unfold to us of the history of organized beings, naturally connecting itself with the causes already set forth, will serve as another proof of them. I shall not enter into any great details on this subject, as they are to be found in my other works; I have already stated some particulars respecting the marine animals, and shall now advert to others which relate to terrestrial vegetables, necessary to the explanation of another great geological phenomenon, now about to be mentioned.

OF COAL BEDS1.

19. The strata of coal, by the great utility of that substance, in regard to its combustible qualities, have procured us information, with respect to the past states of our globe, which we never should have obtained but through this object of public interest; for naturalists would never have attempted to dig so low, and in so many places, beneath the surface of the earth, merely through a spirit of research. I have shown in my "Lettres sur l'Histoire de la Terre," &c. and in the thirteenth and seventeenth of my letters in the " Journal de Physique "," that the substance of coal was formerly peat; and I believe it is now not doubted. But those

1

2

1 M. Alex. Brongniart readily acknowledges that the theory of coal formations, which appears to him the most probable, although proposed long before geology had acquired all the facts which it now possesses, is that of De Luc. Tableau des Terrains, &c. p. 280. 1829. ED.

2 Tom. xxxviii. p. 174. et seq. 1791. Ibid. Part ii. p. 332. et seq.

vegetables, the remains of which having withered and become dissolved without undergoing decomposition, formed that peat, were very different from those which at present produce the ingredients of peat on our continents: this is observable in the stony strata which covered the former, where are found impressions of vegetables which grew at the surface of that ancient peat, and from which they proceeded. Among these impressions, we discover some vegetables which grow at present in the same latitudes, such as the sphagnum palustre, and some of the junci', which form a great part of the mass of our peat, as well as many known ferns; but, in the first place, these last do not belong now to our climates. In addition to which I shall observe, as a peculiar object of consideration, that the vegetables, now unknown, which have contributed to the formation of coal, are not the only monuments of the first vegetation on our globe, which prove that vegetation was in a very different condition from what it is at this day; for we find them likewise in some strata of sand-stone, where we see, among others, the remains of immense tubular and ramified vegetables, to which there is nothing similar among our own. I have designated under the title of THIRD PERIOD, that at which the earth's surface was for the first time divided into sea and land; and while indicating that period as corresponding to the third DAY recorded in the first chapter of Genesis, I observed, that in this " day" the earth was not as

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1 "The vegetables of the coal-pits, properly so called," says Mr. J. A. de Luc, on this passage, are altogether different from our present plants. The information given to the author, respecting the sphagnum palustre, and the junci being found in the coal, must have been erroneous." ED.

yet enlightened by the sun; such is the fact which I have now to consider.

20. Whatever difference there may be between the first vegetables, and those which exist at the present day, had we no other guide in the history of vegetation, we should not assuredly have inferred from thence that those first vegetables were deprived of light. But I shall first propose here a general question of great importance: what would man have been capable of discovering in regard to the origin of the world without Revelation? This question is not a speculative one-it can be resolved by facts alone; and although it is here anticipated, because it is connected with numerous objects which can be developed only in succession, I could not pass by this period in the history of the earth, of which we at present observe the influence, without determining the objects for our consideration in respect to the knowledge acquired by man. I shall show hereafter, relatively to this subject, that all the notions of cosmogony disseminated amongst the most ancient nations, have proceeded alone from Revelation itself, and that all they have added to it, in regard to which there exists no appearance of researches, are mere chimeras, grounded upon those first foundations. But what we may already perceive at this stage is, that Revelation, preserved in all its purity among one of those nations, is the true cause of the progress which mankind has made in the study of nature, and the only guide that has directed them in it; for if we carefully follow out the history of geology, not through the vain fancies of ancient nations, but among men who have at length applied to the study of the actual state of the earth,

in order thence to deduce physically its past states, it will be seen that those researches have all had Genesis in view, whether for the purpose of attack or defence; researches which the pagan cosmogonies, although having in reality the same origin, never have, nor ever could have, suggested. It is the plain narrative of Moses, without details, but exact in respect to the order of events, that has led to the examination of geological monuments, and to the study of chymistry and general physics, as directed to the investigation of the causes which could formerly have produced such great effects upon the earth, and many analogous effects upon the other globes; and it is on reflecting more particularly upon these important words at the beginning of Genesis: "And God said, let there be light!" that we have succeeded in discovering in them a sublime truth, insomuch that none of the great physical effects which we perceive to have been operated, not only upon the earth, but upon other globes, could have commenced without the addition of light, to the other substances which at first constituted the mass of those bodies. What confidence then ought not to be inspired by so exact a confirmation of the most important among the passages of Genesis that had been charged with absurdity, as placing effects before causes-for here all nature attests the necessity of the pre-existence of light to all the physical operations of which we see the effects upon the globes, and in particular that mission of the light which causes the splendour of the heavenly bodies. Now, although we have not as yet found such direct proofs of the pre-existence of vegetables to the emission of light by the sun, we

have, nevertheless, observed circumstances which no longer allow us to consider it as absurd'. We know, I say, on one hand, that the action of an external light upon the planets, necessary at present for the fructification of the greater part of vegetables, is attended by alternate emissions and absorptions of expansible fluids, or of modifications of the surrounding atmosphere, according to certain circumstances, partly connected with the absence or presence of light, but in part likewise with the nature of the vegetables, and with the different states of the air that surrounds them; which in the first place shows that the necessity of an external light may be dependent on circumstances, for we are far from being enabled to determine the manner in which it acts, and in what respect it is necessary in the vegetable economy, which is still involved in mystery. On the other hand, we learn, through geology, that our atmosphere must have been formed, and have experienced great successive changes, in proportion as our mineral strata were produced in the liquid which once covered the whole globe; that when by a first catastrophe of the bottom of that liquid, new lands were formed, the first vegetables which grew there, were very different from those which our globe now produces; but that in proportion as the atmosphere approximated to its present state, plants, and together with them, marine and terrestrial animals, in like manner approached

1 It has been ascertained, that even in the present state of the globe, vegetable existence is not altogether incompatible with the absence of light. Caverns and mines are said, by HUMBOLDT and other naturalists, to produce certain plants, principally those of the cryptogamous class. ED.