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decayed foliage had prepared a soil adapted to the LETTER germination of their arriving seeds. Whatever was brought or wafted, would vegetate only there, where it found a mould fitted for its nature; and thus, within a century after its creation, the surface of the Earth would be in the same state as to its herbage and forests, whether they originated from a particular locality or from an universal formation.

It may be inferred from these considerations, that there is no occasion to indulge in the extravagant conjecture that the whole globe was for countless ages occupied only by plants. They would precede animals in all countries, because they diffuse themselves much more rapidly. No quadruped out-travels the wind. No bird can reach distant islands, continents or mountains, faster than the never-tiring breeze. Nothing living multiplies more profusely and quickly than many of the Botanic races. Hence it is natural that in our fossil remains, Vegetation should often be discerned where no traces of animal life occur; and it is not less so, that it should have pervaded, more or less, every region of our globe, capable of habitation, at an early period after the creation.

The organic relics of our rocky masses correspond with the preceding observations, or are not inconsistent with them and to these, which are the only real evidences we possess of the primeval vegetation of our Earth, let us now direct our attention.

The rocky masses which constitute the crust or upper and external substance of our Earth, display a visible succession and orderly formation. They lie, if viewed in their depth, above and below each other, altho the lower are also found in some parts to rise up and form the mountains, as if they had been

Q

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16

LETTER elevated from below; evincing thereby an abruption, an emergency from a subterraneous position, and great concussion and dislocation. These are the rocks of the Granite class, which are allowed to have been primordial, and to have issued upward from the inner substance of the Earth." The next masses of rocks, the lowest of all known except the granite, are also placed among the primitive formations. The Gneiss is the most prominent of these,18 and all of this class were spread and arranged before any vegetables or animals appeared. The universal absence of all organic remains in these masses has led every one to this conclusion as a satisfactory certainty.19

16 The small part of the bark of the Globe which we are acquainted with, is composed of different mineral substances, which, considered in their mass, constitute Rocks; some homogeneous; some visibly heterogeneous. The heterogeneity is not unlimited in the number, disposition and relation of the parts. On the contrary, it shows in these a constancy which indicates that certain laws have governed these associations.'

The differences, and especially their organic remains, prove, as M. Cuvier remarks, that the bark of the Earth was not made by a single cast: but that the parts which compose it have been successively formed or deposited.' Al. Brongniart, Struct. du Globe, p. 1.

17 Granite shows itself from the greatest known depths, to an elevation of above 1,200 yards above the level of the sea: from below the Gneiss to the gypseous Red Sandstone: and in vast dykes, in many countries.' Al. Brong. ib. 338, 9. 18 The GNEISS rocks are one of the formations most abundantly spread over the globe. Some entire countries are almost wholly formed of it. It is the most ancient stratified rock; below which exist masses that are unknown or rocks not stratified. The summit of the Simplon, and most of the rocks of Sweden, are formed of it.' Ib. 330, 1, 3.

19 The Mica Slate rocks, and the Quarzite ones, are, with those of Gneiss, placed by M. Brongniart as so clearly prior to all organic life, that he calls them Hypozoiques, or inferior to all the rocks which contain organic remains.' p. 327. . . . . .The Limestone, and others which he notices, are usually placed among the primordial rocks, and most of them have no fossils of living substances.

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But after these, organic remains begin to appear; LETTER of which only the Vegetable ones shall be noticed in this Letter.

That vegetable remains abound in that series of rocks and masses which constitute the Coal formations, is universally agreed. Plants were therefore in being before the Coal strata originated: and it is also now the general sentiment, that our coals are a transmutation of vegetable matter into that state,— an extended mass of mineralized peat or turf." But it is not so generally admitted that this was the period of the first evolution of the Botanical Kingdom. It has been affirmed, that no organic remains are found in rocks that were anterior to the coal formation." But this idea has been disproved by later

....

·

20 De Luc's theory on this is adopted by M. Brongniart,-that they are the turf bogs or peat mosses of the ancient world, which had become inundated by sea water. p. 280. De Luc repeats this idea in his last letters: The substance of Coal was formerly Peat.' p. 155. And again declares it to have proceeded from peat which underwent submersion by the waters of the sea. Fossil peat differs from coal only in this, that it has not been mineralized; and that the strata which cover it do not contain ferruginous masses: for, in other respects, the circumstances are the same.' Lett. p. 161. . . . . . Marcel de Serres considers also that the Vegetation of his first, or antediluvian period, formed the beds of coal. Geognesie, p. 22.... So Mr. Bakewell, Geology, p. 161; and Dr. Ure, Geol. p. 165..... Dr. M'Culloch, also, whose valuable experiments have decided the question, ascribes to Coal a vegetable origin. In his Chapters on Coal, Lignite and Peat, he explains at length his ideas or theory on the vegetable conversion to Lignite and Coal. Geol. v. 2, p. 295359. . . . . The same action of water which converts the Vegetable into Peat, can produce the further change to Bitumen, as it does in the earth; tho the time required is very considerable. The prolonged action of water has effected the ultimate change, as it has produced all the inferior ones; and has changed Peat into perfect Lignite.' Ib. 353. . . . . ' Thus the progress of the change can be traced from the Vegetable, thro Peat, to Lignite; and finally to Coal.' Ib. 348.

21 At present, we know of no Vegetable remains of earlier existence than those which belong to the Coal formation.' Parkinson, Oryct. p. 31.

LETTER discoveries. Some places in England show that the VII. Limestone group below the coal contains vegetable

fossils, altho they but rarely occur.22 It is therefore with propriety that the secondary strata, earlier than the coal, have been distinguished into two kinds,those which, by never having fossil remains, prove themselves to have been anterior to all organic life; and those more immediately contiguous to the coal, in which portions or indications of plants occasionally appear.23 The mountain limestone now and then exhibit them, tho not frequently;" and in the sandstone of this portion, very important fossil land vegetables have appeared." The exact truth may there

22 In the Fossil Flora now publishing with so much care and taste by Mr. J. Lindley and W. Hutton, it is stated, Vegetable Fossils occur in all the sandstone and slate beds of the Coal formation; and in many of the members of the subjacent limestone group.' p. 15. . . . The limestone itself has hitherto afforded but few vegetable remains nevertheless, we shall have to notice in the process of this Work some beautiful examples, both from the limestones of Northumberland, and from those in the neighbourhood of Edinburgh.' p. 16. Yet these gentlemen say afterwards in their General Preface, The Coal formation may be considered the earliest in which the remains of land plants have been discovered.' p. x. This is also inconsistent with the fact quoted from them in Note 25.

"M. Al. Brongniart divides the Rocks more ancient than the Coal into these two classes,-Hypozoiques, or under all living things; and Epizoiques, or upon what have been such. Al. Brong. Struct. p. 320.... Dr. M'Culloch remarks that Marine Vegetables occur in the old schists.' Geol. v. 2. p. 297.

"It is in the Mountain Limestone, Transition Limestone, his Hemilysiens Calcareux, that M. Al. Brongniart places his Tableau No. 18, consisting of 'three Fucoides, or Sea-plants; two Calamites; a Sphenopteris, Cyclopteris, and Pecopteris.' Struct. p. 431 and 292, 8.

25 The Cragleith fossil tree, Pinites Withami, was found in 1826, in the great quarry at Cragleith near Edinburgh, which we take to be in a sandstone considerably below the coal formation proper, perhaps even in the Mountain Limestone group. It was 36 feet long, and 3 feet diameter at the base. It seems to have been a tree having an exogenous structure.' Lindley's Fossil Flora of G. Britain, p 9, 12. The Editors cannot quite decide that it belongs to the coniferous

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fore be, that in the coal strata, and in the marine LETTER rocks immediately below them, and with which they seem to have both a chronological and a geological connection, the first remains or indications of vegetable fossils appear.

It is not in the coal itself that the organic relics of the old world appear, or very rarely." But they, or impressions of them, abound in the sandstone and slate beds which form the usual roofs and floors of the actual mineral, and have been hitherto most numerously found in its shale superincumbent." When such a roof is broken and falls, they become immediately visible in all their interesting abundance.28

The primeval vegetation thus disclosed to us has been described to be principally of the Cryptogamous kind: Ferns and fern-like plants, of the horsetail and club-moss tribes, with some of the palm and liliaceous species of the monocotyledonous description,20 be

coniferous tribe. In 1831, a branch of a tree was found there. 'The concentric circles, medullary rays, and pith of an exogenous tree, are distinctly seen.' Ib. p. 13.

26 6

The coal itself very rarely retains any marks of organic structure.' L. & H. Fossil Flora, p. 16. But see further on this topic hereafter.

27 Where shale forms the roof of the workable seams of coal, as it generally does, we have the most abundant display of fossils. The fine particles of which they are composed, having sealed up, and retained in wonderful perfection and beauty, the most delicate outward forms of the vegetable structure.' Fossil Flora, p. 16.

28 Their principal deposit is not in immediate contact with the coal, but about twelve or twenty inches above it. Such is the immense profusion in this situation, that they cause accidents by breaking the adhesion of the shale-bed, and causing it to separate and fall. After an extensive fall of this kind, it is a curious sight to see the roof of the mine covered with these vegetable forms: some of them, of great beauty and delicacy.' Lindl. & Hutt. Fossil Flora, p. 16.

M. Marcel de Serres considers the remains of the first period of vegetation to have formed the coal-beds. They are remarkable