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account for the intermixture of the debris of vegetables and animals with marine bodies, in many parts of the

peat under the form of coal, on the beds of which substance many stony strata, of different kinds, were subsequently formed; but its vegetable origin is always manifestly shown by the plants of various species found in the stony strata that immediately cover it. The peat-mosses formed on islands which sunk at a later period, when the liquid no longer possessed this mineralizing faculty, were covered likewise with strata of a different nature; but in these, the peat, and the wood beneath it, are found with little alteration." Geol. Travels in France, &c., Vol. i. § 199. See also Letter IV. § 21, and Journ. de Physique, Tom. xxxix. (part ii.) p. 346. 1790; xli. (part ii.) pp. 221-229. 1792; xlii. p. 233. et seq. 1793.

In a hill, in the district of Lauenstein, north of the Elbe, (described in the Geological Travels in France and Germany, Vol. i. § 360.) three beds of coal, one above the other, have been discovered, their sections appearing between those of the stony strata. These beds have evidently subsided at different periods. The lowermost rests on strata of a very hard marble containing marine bodies; this bed is separated from the next above it by strata of lime-stone likewise enclosing marine bodies. Between the second bed of coal and the third above, there are strata of sand-stone. It is obvious that this last bed has been submerged at a later period than the others; for, although precipitations of the stony strata were still taking place, the sea had lost its power of mineralizing the peat into coal: instead of the latter, we find only peat reduced to a blackish powder, preserving, however, its combustibility.

De Luc's theory respecting the islands of the ancient sea, furnishes in a variety of instances the most satisfactory explanations of the phenomena. In a reply to a memoir on fresh-water formations published in 1811, by M. Alex. Brongniart, our author remarks that this naturalist is mistaken in placing the origin of those deposits on our continents, posterior to the period of their being abandoned by the ocean; that in the same manner as coal and fossil peat, they had been formed on islands and peninsulas of the ancient sea, which owing to the catastrophes occasioned by the infiltration of its waters, had sometimes been submerged, and at other times had re-appeared above the surface.

land'. Several other islands, not submerged, became, by the last retreat of the sea, the summits of our

'The occasional intermixture, however, of marine shells belonging to the latest formations, with the fossil remains of terrestrial animals, presents a geological problem of no easy solution. In order to account for this phenomenon, Mr. J. A. de Luc conceives that there existed deep gulphs and mediterranean seas, in the beds of which the bones of the quadrupeds may have remained for a considerable time, having been drifted thither by the ancient rivers, or the waves of the ocean. It was then that many of the bones were covered with oysters, millepores, serpulæ, &c. which adhered to their surface in the same manner as on the coast of Naples, fragments of urns and other utensils are found beneath the waters of the sea covered with the productions of marine polypi or bivalves, or sea-worms. The same aqueous revolution must have buried all the organic bodies, terrestrial and marine, together with the forests; and hence the intermixture of the wood and osseous remains with the shells. The tracts of land were left dry by a subsequent revolution, when an universal depression of the level of the ocean took place. It is to this last revolution that our author adverts when he says, that not many ages have elapsed, since the continental parts of our globe were abandoned by the sea. See Sect. II. of this Introduction.

As an instance of the association of bones and shells, may be adduced the osseous fragments dispersed in the stratum called Norfolk crag, or upper marine formation, as described by Mr. R. Taylor, in his geological dissertation, to which reference has been already made, in Sect. II. of this Introduction. Mr. Taylor considers that these fragments are the relics of those animals which "roamed along the antediluvian shores and æstuaries, and fed amidst the forests of a former world." This opinion, however, according to Mr. J. A. de Luc, is inadmissible, inasmuch as terrestrial animals cannot inhabit a land recently covered by the ocean. Such an association of the terrestrial with the marine, can proceed only from some sudden revolution. The waters of the ocean sweeping over a great portion of the globe, drifted the osseous fragments from the dry land to the bottom of a neighbouring mediterranean sea, full of shells. Mr. Taylor adduces proofs of the

present mountains, and the principal sources of the vegetables and animals of the new continents'.

SECTION V.

Agreement of Cuvier and Alex. Brongniart with De Luc.

The general correctness of the statement of geological phenomena, here set forth from De Luc, together with his views on the respective causes and operations connected with them, as suggested by that great naturalist, have been acknowledged and adopted by the celebrated Cuvier.

And first, that our strata (which had been fractured into masses that became ridges of mountains,) were originally formed in a liquid, in which for a great length of time no organic beings existed, is admitted in the following passage of Cuvier's "Recherches sur les

erosive power of diluvian currents exercised upon the stratum of the crag, the same probably which brought down the bones of the quadrupeds upon that stratum. The crag must have formed the bed of a shallow sea, in the vicinity of which there existed lands covered with forests, and inhabited by large quadrupeds. The great aqueous revolution above spoken of, drifted the fragments of wood and the osseous remains, and intermingled them with the shells; at a subsequent period, the level of the ocean sank, and the bed of shells, called crag, was left dry.

The same association is ascertained with respect to Piedmont, the Plaisantin, and Tuscany; and also in regard to the basins of the rivers of Russia, such as the Jaik, the Oby, the Irtish, and the Kama, which discharges itself into the Volga.

1 The author accordingly considers Mount Ararat to have been one of the islands in the ancient sea. See Letter VI. § 18. and Journ. de Physique, Tom. xli. part ii. p. 221. et seq. (1792.)

Ossemens Fossiles :"-" The first sea

It is impossible to

was unin

habited ... deny that the masses which constitute our highest mountains, have been originally in a liquid state; that for a long time they were covered with waters, in which no living beings existed." He then speaks of the overturnings, the disruptions, and the fissures observable in the strata of these masses, as well as in those of more recent formations 1.

The connection established by the author between the successive changes in the liquid and successive revolutions at the bottom of the sea is recognised in the following passage:-" the displacements of the strata were accompanied and followed by changes in the nature of the fluid.....

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The general connection that has been pointed out by De Luc between the formation of the strata and the history of organic bodies on our globe, is fully allowed by Cuvier in the same work. "It was," our author had said, "the organic bodies contained in our mineral strata which gave birth to geology". "their succession in our strata indicates a certain succession of periods in their history, connected with the formation of these strata "It is to fossil remains alone," says Cuvier, "that we owe even the commencement of a theory of the earth........

1

3 "

See Prof. Jameson's fifth edition of the Essay on the Theory of the Earth, p. 20. The Professor has noticed Cuvier's adoption of the opinion of De Luc, that the more ancient strata, originally formed in a horizontal situation, have assumed their present highly inclined position, in consequence of subsidences that have taken place over the whole surface of the globe. Essay, &c. p. 333.

2 Ibid.

p. 11.

3 Letter II. § 14. I. § 7.

without them we should perhaps never have even suspected that there had existed any successive epochs, and a series of different operations, in the formation of the globe'.'

Cuvier also, agreeably to what had been stated by our author respecting the existence of organized beings, asserts that the marine animals began to exist from the earliest periods of the formation of the transition or intermediate strata, and that a long time after, the land quadrupeds appeared in considerable number.

The changes which, according to De Luc, those organized beings gradually underwent, are in like manner admitted by the French naturalist, together with the cause by which these changes were produced. "All the organized beings," says the former, "vegetables as well as animals, whether marine or terrestrial, underwent great changes, in proportion as the liquid....... varied 2." "There has been," remarks Cuvier, "a succession of variations in the economy of organic nature, which has been occasioned by those of the fluid in which the animals lived, or which has at least corresponded with them 3."

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De Luc had observed that the organized beings, of which the remains are found in the last strata produced by the sea previously to its retreat from our continents, approximate to the species now existing, in proportion to the lateness of their appearance on the globe, and consequently to the shortness of the time during which they had been subjected to the

1

Essay on the Theory, &c. p. 51.

3 Essay on the Theory, &c. p. 12.

2 Letter III. § 37.

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