The World Before the Deluge

Dr. Lindley. Brongniart. rCryptogamous Amphigens, ]

I. Thallogens - -, or Cellular Crypto- |-Lichens, Sea-weeds, Fungi. ( g^-ims )

II. Acrogens " '^^^^^^^^Z.o. ''^'^'^?^^'^'III. Gymnogens -^ nerms'^ °^-°"- - r™^°^! ( ^*^^^^^^^ •^'^^ ^y^^^^- ' r Composites, LeguminosDe, Um-jY -p. ^ (Dicotyledonous Angios- } belliferse,Cruciferce, Heaths. ^Oo * '^ perms -. - - ^ All European except Coni- C fers.

V. Endogens - Monocotyledons - - - - |^'"^'''^.^^ses!'' '^^°''' ^'''^'''

Calamites are among the most abundant fossil plants of the Carboniferous period, and occur also in the Devonian. They are preserved as striated, jointed, cylindrical, or compressed stems, with fluted channels or furrows at their sides, and sometimes surrounded by a bituminous coating, the remains of a cortical integimient. They were originally hollow, but the cavity is usually filled up with a substance into which they themselves have been converted. They were divided into joints or segments, and when broken across at their articulations they show a number of striae, originating in the furrows of the sides, and turning inwards towards the centre of t^ie stem. It is not known whether this structure was connected with an imperfect diaphragm stretched across the hollow of the stem at each joint, or merely represented the ends of woody plates of which the solid part of the stem is composed. Their extremities have been discovered to taper gradually to a point, as represented in C. cafmccfofutis (Fig. 64), or to end abruptly, the intervals becoming shorter and smaller. The obtuse point is now found to be the root. Calamites are regarded as Equisetaceous plants; later botanists consider that they belong to an extinct family of plants. Sigillarice are the most abundant of all plants in the coal formation, and were those principally concerned in the accumulation of the mineral fuel of the Coal-measures. Not a mine is opened, nor a heap of shale thrown out, but there occur fragments of its stem, marked externally with small rounded impressions, and in the centre slight tubercles, with a quincuncial arrangement. From the tubercles arise long ribbon-shaped bodies, which have been traced in some instances to the length of twenty feet.

In the family of the Sigillarias we have already presented the bark of S. Icevigata, at page 138; on page 155 we give a drawing of the bark of S, reniforniis^ one-third the natural size (Fig. 65).

3

COAL MEASURES.

Fig. 63.— Sphenophyllum restored.

In the family of the Asterophyllites, the leaf of A. fo/iosa (Fig. 66); and the foliage of Annudaria orifolia (Fig. 67) are remarkable. In

Fig. 64.—Calamites cannzeformis. One-third natural size. addition to these, we present, in Fig. 63, a restoration of one of these Asterophyllites, the Sphenophylium, after M. Eugene Deslongchamps. This herbaceous tree, like the Calamites, would present the appearance of an immense asparagus, twenty-five to thirty * feet high. It is represented here with its branches and Sronds, which bear some resemblance to the leaves of the ginkgo. The bud, as represented in the figure, is terminal, and not axillary, as in some of the Calamites. If, during the Coal-period, the vegetable kingdom had reached its maximum, the animal kingdom, on the contrary, was poorly represented. Some remains have been found, both in America and Germany, consisting of portions of the skeleton and the impressions of the footsteps of a Reptile, which has received the name of Archegosaurus. In Fig. 68 is represented the head and neck of Archego- Saurus minor, found in 1847 in the coal-basin of Saarbruck, betweenStrasbourgand Tréves. Among the animals of this period we find a few Fishes, analogous to those of the Devonian formation. These are the Holoptychius and Mega- Uichthys, having jaw-bones

XI.—Ideal view of a marshy forest of the Coal Period.

COAL MEASURES.

armed with enormous teeth. Scales of Pygopteriis have been found in the Northumberland Coal-shale at Newsham Colliery, and also in the Staffordshire Coal-shale. Some winged insects would probably join this,1.m slender group of living beings. It may then be said with truth that the immense forests and marshy plains, crowded with trees, shrubs, and herbaceous plants, w^hich formed on the innumerable isles of the period a thick and tufted sward, were almost destitute of animals.

On the opposite page (Pl. XI.) M. Riouhas attempted, under the directions ofM. Deslongchamps, to reproduce the aspect of Nature during the period. A marsh and forest of the Coal-period are here represented, with a short and thick vegetation, a sort of grass composed of herbaceous Fern and mare's-tail. Several trees Fig. 65.— Sigillaria reniformis iof forest- height raise their heads above this lacustrine vegetation. On the left are seen the naked trunk of a Lepidodendron and a Sigillaria, an arborescent Fern rising between the two tnmks. At the foot of these great trees an herbaceous Fern and a Stigmaria appear, whose long ramification of roots, provided with Fig. eC— Asterophyllites foUosa.

reproductive spores, extend to the water. On the right is the naked

Fig. 68.—Head and neck of Archegosaurus minor. trunk of another Sig¢//aria, a tree whose foliage is altogether unknown, a Sphenophylium, and a Conifer. It 1s difficult to describe with precision the species of this last family, the impressions of which are, nevertheless, very abundant in the. Coal-measures. In front of this group we see two trunks broken and overthrown. These are a Lepidodendron and Sigillaria, mingling with a heap of vegetable débris in course of decomposition, from which a rich humus will be formed, upon which new generations of plants will soon develop themselves. Some _herbaceous Ferns and buds of Calamites rise out of the waters of the marsh. A few Fishes belonging to the period swim on the surface of the water, and the aquatic reptile Archegosaurus shows its long and pointed head—the only part of the animal which has hitherto been discovered (Fig. 68). A Stigmaria extends its roots into the water, and the pretty Asterophy lites, with its finely-cut stems, rises above it in the foreground. A forest, composed of Lepidodendra and Calamites, forms the background to the picture.

Formation of Beds of Coal.

Coal, as we have said, is only the result of a partial decomposition of the plants which covered the earth during a geological period of immense duration. No one, now, has any doubt that this is its origin. In coal-mines it is not unusual to find fragments of the very plants whose trunks and leaves characterise the Coal-measures, or Carboniferous era. Immense trunks of trees have also been met with in the middle of a seam of coal. In the coal-mines of Treuil,* at St. Etienne, for instance, vertical trunks of fossil trees, resembling bamboos or large Equiseta, are not only mixed with the coal, but stand erect, traversing the overlying beds of micaceous sandstone in the manner represented in the engraving, which has been reproduced from a drawing by M. Ad. Brongniart (Fig. 69).

In England it is the same; entire trees are found lying across the coal-beds. Sir Charles Lyell tells ust that in Parkfield CoUiery, South Staffordshire, there was discovered in 1 854, upon a surface of about a quarter of an acre, a bed of coal which has furnished as many as seventy-three stumps of trees with their roots attached, some of the former measuring more than eight feet in circumference; their roots formed part of a seam of coal ten inches thick, resting on a layer of clay two inches thick, under which was a second forest resting on a band of coal from two to five feet thick. Underneath this, again, was a third forest, mth large stumps of Zepidodrndra, Calamites, and other trees. J In the lofty cliffs of the South Joggins, in the Bay of Fundy, in Nova Scotia, Sir Charles Lyell found in one portion of the coal-field 1,500 feet thick, as many as sixty-eight different surfaces, presenting evident traces of as many old soils of forests, where the trunks of the trees were still furnished with roots. §

We will endeavour to establish here the true geological origin of coal, in order that no doubt may exist in the minds of our readers on a subject of such importance. In order to explain the presence of coal in the depths of the earth, there are only two possible hypotheses. This vegetable debris may either result from the burying of plants brought from afar and transported by river or maritime currents, forming immense rafts, which may have grounded in different places and been covered subsequently by sedimentary deposits j or the trees may have gro\Mi on the spot where they

• ** Elements of Geology," p. 480. f Ibid, p. 479. % Ibid, p. 479. § Ibid, p. 4S3

i6o THE WORLD BEFORE THE DELUGE.

perished, and where they are now found. Let us examine each of these theories. Can the coal-beds result from the transport by water, and burial

Fig. 69. — Treuil coal-mine, at St. Etienne.

underground, of immense rafts formed of the trunks of trees? The hypothesis has against it the enormous height which must be conceded to the raft, in order to form coal-seams as thick as some of those which are worked in our collieries. If we.take into consideration the specific gravity of wood, and the amount of carbon it

Iff

FORMATION OF BEDS OF COAL. l6l

contains, we find that the coal-deposits can only be about seven-hundredths of the volume of the original wood and other vegetable materials from which they are formed. If we take into account, besides, the numerous voids necessarily arising from the loose packing of the materials forming the supposed raft, as compared with the compactness of coal, this may fairly be reduced to five-hundredths. A bed of coal, for instance, sixteen feet thick, would have required a raft 310 feet high for its formation. These accumulations of wood could never have arranged themselves with sufficient regularity to form those well-stratified coal-beds, maintaining a uniform thickness over many miles, and that are seen in most coal-fields to lie one above another in succession, separated by beds of sandstone or shale. And even admitting the possibility of a slow and gradual accumulation of vegetable debris, like that which reaches the mouth of a river, would not the plants in that case be buried in great quantities of mud and earth? Now, in most of our coal-beds the proportion of earthy matter does not exceed fifteen per cent, of the entire mass. If we bear in mind, finally, the remarkable parallelism existing in the stratification of the coal-formation, and the state of preservation in which the impressions of the most delicate vegetable forms are discovered, it will, we think, be proved to demonstration, that those coal-seams have been formed in perfect tranquillity. We are, then, forced to the conclusion that coal results from the mineralisation of plants which has taken place on the spot; that is to say, in the very place where the plants lived and died.