mixed with impurities such as may be attributed to the invasion by waters holding argil in suspension, and whose periodical return has been one of the causes of decomposition. To the influence of these immersions must be attributed the effects of erosive currents, which have brought together, at certain points, sometimes thick zones of specular coal, and sometimes beds wherein carbonaceous schist or clay predominates.

Thus, then, the coal-fields may have been produced, in great measure, by the growth, on the spot, of small vegetables, in the manner of peat or turbaries; whilst the larger vegetables may have been drifted from distant and elevated points, when the oscillations of the surface produced the interruption or the renewal of this generative action, in placing the coal surface above or below the level of the sedimentary waters.

This hypothesis explains, not only the formation of the thin and multifold beds, in the basins of the north of Europe, for instance, but they also agree with the generation of the thick and limited basins of the south, and of the great accumulations, like those of Montchanin.

The distinctness of the planes of separation demonstrate that the two principal generators were not susceptible of being confounded; in other words, the deposits of sand and clay were effectuated in the water, whilst the coal, on the contrary, has been produced above these waters. Coal, then, is not, properly speaking, a sedimentary deposit, produced by the transportation of vegetables, or by floating rafts, as has sometimes been supposed; and yet its production has taken place very near to the surface of the water, since it has had frequent penetrations of the two generating influences, which thus accumulated, side by side, products so different.

These views of the origin of coal ought evidently to be extended to all the series of fossil combustibles, which represent the vegetable accumulations of various geognostic periods. The anthracites of the transition formations owe their dry and meagre nature only to the difference in the mode of decomposition, determined by the special conditions of the surface of the globe at that early epoch. It is to be remarked, that if our theoretical ideas of the formation of the globe induce us to attribute this difference to the phenomena of temperature and pressure, which appear to have affected the rocks of the anthraxiferous epoch, this opinion is completely confirmed by the anthracitous state of the combustibles, subsequent to the coal period, which we encounter in the metamorphic formations. We cannot, in fact, doubt that, in the second case, the phenomena of heat and pressure are the modifying causes of beds which originally consisted of coal or lignite.

The tertiary LIGNITES have generally preserved their ligneous tissue so fully, that we can recognize, in many of the fragments, the nature of the constituent wood. The fir, the alder, the beech, and the oak, form the most frequent debris of the lignites of the Alps, and they thus denote a complete change in the vegetation of the

earth since the coal period. They are the true fossil forests, which likewise differ from the coal beds by a more circumscribed accumulation, and by a less complete stratification.

In certain exceptional cases, the lignites have a compact structure, almost comparable to that of coal. They then constitute what is called common jet. This is the ordinary character of the lignites in the environs of Marseilles; which give rise to an annual production of more than a hundred thousand tons. These lignites form seven perfectly regular and stratified beds, within the tertiary basin, at Fuveau, Crest, Auriol, &c. ; the thickness of each of which beds [from one to three feet,] preserves such constancy that it may be recognized by this character alone, in the divers parts of the basin. These beds are comprised between calcareous strata; they are subject to the numerous movements, inclinations, folds, faults, and upheavings which have disturbed the various portions of the tertiary basin.

Among these accidents, there is one which is peculiar to the lignites, and which is known under the denomination of mouillères. These consist of portions of beds where the lignite is so fissured and decomposed that it has become very permeable to water. The workings encounter the double difficulty of abundant infiltration, and a production of no value. In their normal state these lignites have much the appearance of coal, but they have not its quality. Nevertheless, in certain positions, in Tuscany, for instance, we find some small beds of a lignite sufficiently perfect to furnish a coke, on distillation.

The general character of lignite is such, that it cannot be considered as possessing a regularity comparable to the coal beds.

Portland Oolite Beds-Contain Zamia, fragments of which are found in the lower calcareous bed of the group-or perhaps in the inferior portion of the cretaceous series. These plants are accompanied by paladinæ or helices, which consequently indicate the passage of fresh water in the seas of this epoch, where are seen the remains of large coniferæ, rooted in the soil, analogous to the Araucaria, now strangers to the present climate of England. But in the midst of these coniferæ we find plants which have a resemblance to the Cycas and the Zamias of the tropical climates, and also the animal relics which approach to those of the same zone. The dirt bed of Portland, which incloses trees still in place, attests the existence of a vegetable soil, of earth almost dry, which rests upon the marine deposits. This bed has since been recovered by very powerful beds of fresh-water limestone, and then passes under the green sand which follows the chalk.

The Wealden group-incloses various vegetable debris-some of which resemble that of the Portland beds and we meet with, in place, and in a siliceous state, the trunks of Cycadeas; Mantellia nidiformis. With these occur various species of coniferæ, besides the fragments of equisetacea and forms of a peculiar species.

Trias, or the Grès Bigarré, or copper group. This great formation, which in France has received the name of Trias, because it

incloses three principal parts, is composed of deposits of sandstone and marls, of varied colours, which have given to the sandstone the name of Grès Bigarré, [red and white] and to the marls, that of Marnes Irisées. The two latter in England are known under the name of the upper new red sandstone and red marl.

In this group vegetation has undergone great modifications. The ferns and the gigantic equistaceae have considerably diminished; while the coniferæ, on the contrary, have become more numerous: plants, analogous to the Zamia, and perhaps to the Cycas, formed at that time an important portion of the flora of Europe; a prelude to the immense development which they made in the succeeding epoch —“l'époque jurassique," or lias.

Vegetable debris and combustibles of the Molasse.* This tertiary formation occurs above the Calcaire Grossier, in the environs of Paris.

The Molasse is very rich in combustible; it encloses the lignites of Languedoc; of Switzerland; the most part of those in Germany, as well as those of Cologne. All the lignites appear to have been principally formed by the coniferæ, of which we are able to recognize the tissue, either in the mass of combustible or in the wood which is disseminated in the midst of the various deposits.

It is known, however, that in this formation there are also many dicotyledonous plants, the wood of which is found disseminated here and there; sometimes in a silicified state, clearly exhibiting the tissue peculiar to this class of vegetables, and characterised, above all, by the presence of large longitudinal vessels.

Leaves also exist; often abundantly, even in the clays which accompany the lignites, and in these can be recognized distinctly the characters which the dicotyledones present. Among them are those of the walnut, the maple, elm, birch, &c.

There exist even fruits, which often cannot be distinguished from those which we find at the present day in our climate.

Finally, there are found in this formation the remains of monocotyledonous plants. This wood presents all the structure of the palms; that is to say, an assemblage of ligneous bundles, disposed longitudinally, without regularity, in the middle of a cellular tissue, as in Palmacites lamennois.

CUPRIFEROUS LIGNITES.

Vegetable remains under this form present themselves in various geological positions and circumstances, which will be noticed in the progress of this work.

In the provinces of New Brunswick and Nova Scotia they occur in the regular coal measures. Mr. Henwood has mentioned this interesting fact that lignites, consisting of ferns and other coal plants occur impregnated with rich vitreous copper ore and coated with

* Cours Elémentaire d'Histoire Naturelle, par M. F. S. Beudant.

green carbonate of copper, on the Nipisiguit, near Bathurst in New Brunswick. These vegetable remains are, according to Mr. Logan, partly converted into coal, and partly replaced by gray sulphuret of copper. The same occurs in the neighbourhood of Pictou in Nova Scotia, in considerable quantities, and also within the limits of the same coal-field at the Joggins, on the Bay of Fundy. On the Nipisiguit it has even been attempted to work the deposit as a copper mine; but, on account of the irregular distribution of the organic remains, the operations became uncertain and led to the abandonment of the work. This bed is from two to four feet in thickness.†

In Pennsylvania, United States, beds of vegetable stems, impregnated with vitreous copper and green carbonate, occur in the shale or argillaceous beds at the base of the Devonian or old Red Sandstone series. In two or three instances, within our own observation, these were commenced to be worked as copper mines, but the quantity of ore was found insufficient for productive operations. The mineral occurs in the form of rich gray sulphuret of copper. So far as our remarks have extended, it is only the terrestrial and not the marine vegetation of this formation that is cupriferous.

In the State of New York, cupriferous lignites occur in about the same geological position, in the Catskill mountain series. They consist, like the preceding, of vegetable casts, replaced by gray sulphuret and carbonates of copper.‡

Professor Del Rio mentions certain beds of this character with which he had become acquainted.

In Russia, in the carboniferous beds which are considered by Mr. Murchison to be of the same age as the Zechstein of Germany and the magnesian limestone of England. The flora is peculiar to it; and the fossil stems and leaves of plants are very general indications of copper ore, which, in the form of gray oxide and green carbonate, is disseminated through or arranged around them.

The Kupfer Schiefer of Germany represents this metalliferous deposit on a smaller scale.§

In the Tyrol, in the upper tertiary coal beds of the valley of the Inn-cupreous vegetable fossils occur.||

Thuringia is remarkable for a cupriferous schist, with lignites and fossil fishes.

In the Spanish Pyrenees, Mr. Logan examined, within the coal measures, a bed which presented a combination of coal and gray sulphuret of copper, in the form of vegetable casts. These occupied an eighteen inch seam, cropping out regularly and extensively. It was then worked as a copper mine, and promised a profitable return. T In Ireland, in a bog on the east side of Glendore Harbour, the

Mr. Henwood in Trans. Royal Geol. Soc. of Cornwall, 1840.

+ Report of the Geological Survey of Canada, May 1, 1845, p. 63. Mather's Fourth Report of New York Geology, p. 229. Proceedings Geol. Soc. of London, Vol. III. p. 751.

Ibid. Vol. I.

Logan's Report on the Geological Survey of Canada, May 1, 1845, p. 64.

peat was found to be highly impregnated with copper, which was extracted from the burnt ashes.*

In Scotland and England, some of the beds of the old red sandstone have a green tinge, and the more argillaceous beds are mottled with red and green. The former hue arises from the oxide of iron, the different tints depending upon the amount of iron in the beds and on its state of oxidation, while the green colour is ascribed to the presence of copper. Whether vegetable casts occurs in these beds. as in the United States, we have not learned.

TURBARIES, PEAT-BOGS-TOURBIERES, PEAT-MOSSES.

In the succeeding pages will be found copious details, (taken from the foreign portion of the first edition,) in relation to this useful combustible the most recent deposit, if we may so employ the term, but nevertheless by no means the least valuable, of the class of fuels. which we have to bring under consideration. Respecting the origin of these modern deposits, which bear some resemblance to coal-fields, it is not uninteresting to trace the process of their accumulation or development.

Turbaries, formed in depressions of the soil, where the shallow waters constantly remain, are found dispersed, here and there, on the surface of plateaux more or less elevated, or upon low plains, and often follow the direction of the valleys, whose hollows they fill. These deposits sometimes present several beds of the combustible, separated from each other by argillaceous, sandy, or calcareous matters; now and then filled with the remains of aquatic or terrestrial mollusques which still live in the country.†

They only originate under peculiar circumstances. They are formed neither in running waters, nor in deep lakes, nor in the transient pools of water which occasionally dry up. It is only produced. in places where the waters stagnate, or are slowly renewed, and have an inconsiderable depth.

The production of peat is principally due to the accumulation of cellular vegetables, which are constantly submerged and which multiply with rapidity; such as the sphagna, confervæ, &c. To these are added a great number of terrestrial vegetables, which are brought thither by streams, either in their ordinary condition, or during inundations. Frequently, also, we find large trees, which are buried more or less deeply in the moss, and particularly in the lower parts, where they are accumulated upon the sands and clays which form the base. Sometimes these trees appear to be standing, but most frequently they seem to have been broken off on the spot, and thrown down near their roots, which are seen fixed at the bottom of the turbary. In certain cases they are extremely numerous, and seem to indicate entire forests which have been buried in the same spot where

Jameson's Mineralogy of the Scottish Isles. † Beudant, Geologie, p. 98.