Leo Lesquereux

“ But some deposits of peat are so recent that their beginning is positively remembered by old men, who have seen them grow to some thickness where as children they had seen only stagnant pools, or a forest, or a muddy swamp. All these peat deposits, like the beds of coal and of lignite, are found in connection with vegetable remains which are either dead and cover them entombed in the clay of their surface, or are still living and deposit and heap their woody matter upon them, thus constantly increasing their thickness. ”

“ The identification of the species is therefore very difficult, especially when it has to be made, as is generally the case, from fragmentary specimens. It is rendered still more embarrassing by the fact that the bark of some species of sigillaria is composed of different thin layers, easily separated, on which the leaf scars, though superposed, differ upon each layer. The club mosses of our time rarely have stems half an inch in diameter; those of the coal, or the lepidodendron and sigillaria, were represented by trees sometimes 2 ft. ”

“ For the action of heat does not deprive the coal of any part of its constituents; it merely quickens the slow burning or metamorphosis of the matter, the ultimate result of which is the entire reduction of the oxygen- and hydrogen-producing volatile gas into compact or condensed mineral combustible, a mere compound of the original elements of wood modified under peculiar influences.—The great Alleghany coal field extends from the middle of Alabama to northern Pennsylvania, and occupies portions of Alabama, Georgia, Tennessee, Kentucky, West Virginia, Virginia, Ohio, and Pennsylvania. ”

“ A splendid specimen from the upper Devonian of Indiana, a stem half a foot in diameter, has its surface fluted exactly like that of a calamites, while its internal structure is related to that of araucaria.—The ferns have the most abundant species of the carboniferous period; already more than 600 have been described from this formation. Of these, about 200 species have been found in the coal fields of the United States, more than 50 of which appear to be indigenous or have not till now been observed in Europe. ”

“ If the more marked characters which indicate the several species of mineral coal are easily recognized at first sight, and if everybody knows the bituminous coal from the anthracite or the cannel, it is not the less certain that, considering the matter in itself and in its compounds, coal is an indivisible whole. Not only have all the kinds of coal the same constituent chemical elements, merely varying in proportion in a slight degree, but all the varieties of coal, of bituminous especially, are found in some localities in the same vein. ”

“ The calamites, which have left very abundant remains in the coal, are closely related by their hollow articulated stems with bark vertically and equally fluted, by their fructifications, and by their structure, to living species of equisetum (horsetail) . But they have the same enormous proportions in size as remarked for lepidodendron and sigillaria compared with club mosses. Their trunks vary from 1 to 6 in. in diameter, their length from 6 to 40 ft. They appear to have grown close together and in thickets, at least in some localities ”

“ Often the original form of the plants from which these woody fibres are derived (bark of lepidodendron, sigillaria, calamites, leaves and stems of ferns, &c.) is visible to the naked eye. In some cases a piece of coal a few inches square is seen with its faces covered with branches and leaves of ferns perfectly distinct in their outline and nervation; and in that way as many as five species have been identified upon the same surface, from their carbonized skeletons. In other cases, as in cannel coal, the fibrous texture of the matter cannot be recognized at first ”

“ COAL, a black, opaque, inflammable substance, generally hard and compact, though laminated and stratified in beds between layers forming the crust of our earth. Coal has become one of the essential elements of modern civilization; in fact, the progress of the civilization of a country is now recorded by the amount of coal obtainable and employed by the inhabitants in a given time.—Mineral coal is a compound especially of carbon or of decomposed woody matter, with inflammable substances and hydrogen and oxygen gases. ”

“ This is a great mistake, for indeed nothing but the growth of the materials upon the place where they have been buried and transformed into coal can satisfactorily account for the immense proportion of woody matter in the deposits. The comparative caloric power of wood, peat, and coal has been found to be on an average represented by the proportion of 30 for wood, 37 to 40 for peat, according to its age, and 60 for bituminous coal. We have seen above what is the average production of wood under the best regulated cultivation of Europe. ”

“ The analysis of caking coal fails to show any difference even in the proportion of the constituent elements from that of some kinds of dry or non-caking coal. Indeed, the character of the coal, where closely examined, is constantly variable in the same bed at the same mine, even upon the same square foot of matter, as recognized from specimens when taken at the same place from the roof to the bottom of the bank, although little or no difference is observed in a large quantity as it comes from the mine. ”

“ With some species of ferns of the coal measures, its flora is represented by large calamites, a genus whose species have the texture and outside form of the horsetail plants of our time, but of an immense size, and especially with new types of conifers. In North America the Permian formations are mostly composed of thick strata of magnesian limestone, overlying the upper coal measures of the west, near and along the Missouri river, especially in Kansas, and also in the Rocky mountains, where it generally underlies the cretaceous formation. ”

“ The combustible matter is abundant enough to percolate through the fissure with water; it is also obtained from the shale by distillation. Even these black shales have been used for fuel, giving a bright flame, though they do not consume. They have been constantly searched for coal; but no coal has been found in this formation, which from its fossils is evidently of marine origin. With the bones and teeth of large fishes, it has also the remains of seaweeds to which its bituminization is due. ”

“ Peat is formed in shallow water or in bogs, by the growth of plants which may be called bog plants, and which belong to a peculiar group of vegetables composed essentially of woody tissue and living either in water or above water, according to local circumstances. The species of plants forming peat in our time do not thrive out of the bogs, neither do land plants invade the bogs and contribute by their remains to the composition of peat. ”

“ The process of transformation of vegetable matter into peat is due to the presence of water, as is apparent from a consideration of the different modes of decomposition of vegetable matter as explained by chemistry. When wood is immersed in water and thus guarded against the action of the atmosphere or of the carbonic acid which causes its decay, it is preserved sound for a very long time. ”

“ The presence of graphite in the carboniferous strata of Rhode Island, and the close likeness of some beds of anthracite of this basin, which in some of its veins is scarcely distinguishable from graphite, point to vegetables for the origin of this substance. For even the hardest layers of anthracite or graphite of Rhode Island bear well preserved remains of plants of the carboniferous period, and evidently their carbon has been derived from vegetable life. ”

“ The archæan rocks, also called primitive rocks, are therefore the only ones universally formed, all the others depending upon local abrasions for their materials, which, transported and deposited mostly by water, are local in their distribution. Animal life is now, and must have been from the beginning, dependent upon vegetable life as the only source of its food. The first traces of organic remains should for this reason represent plants. The primitive or archæan formations have deposits of graphite or plumbago, a matter essentially composed of carbon. ”

“ In anthracite the amount of carbon is still increased, while that of hydrogen and oxygen has become proportionally less, and the volatile matter is reduced to a minimum. Hence pure anthracite is debituminized and burns without any flame. The anthracite of Pennsylvania becomes harder and more free from gas in proportion to the distance of the basins eastward from the Allegheny mountains, where its beds are folded in more numerous and sharper flexures. ”

“ The amount of volatile combustible matter in its composition is extremely variable, and therefore its appreciable characters, either in its value as a combustible material or in its appearance, vary in the same degree, considerably blending the classification and multiplying its names. With a moderate proportion of inflammable gases it is dry coal; with more bitumen it becomes fat coal, which passes to caking coal when in burning the matter softens and coalesces like paste. ”

“ But nowhere has the land vegetation been luxuriant enough to produce coal, though the genera, if not the species, represented by these plants are closely allied to those of the carboniferous period. The upper Devonian, especially the Chemung, presents by its vegetable remains the same character as those of the former period; but the land vegetation becomes more and more predominant, yet not enough to produce coal. Moreover, most of the upper Devonian strata represent beach formations by their red shales. ”

“ Indeed, in regard to the population of the gold-mining countries of the Rocky mountains, and to the building of railroads across the plains from the Missouri to the Pacific, the lignitic basin of the west is for the future as important as are for the present the Appalachian coal beds or the coal fields east of the Mississippi river. ”

“ By successive annual growth and deposits this groundwork becomes thick and more solid; shrubs and even trees take root and grow upon it, till the mass becomes too heavy, is split or torn asunder, and sinks to the bottom. Other series of vegetation may begin again in the same way and be successively heaped upon one another, peat beds and forests, till the basins are filled. From some of these filled lakes now discovered under thick strata of humus, peat and wood, and even large trees which could be used for building, have been dug out to a thickness or a depth of 75 ft. ”

“ When the materials which enter into the composition of peat are growing in a deep basin of water, and their debris are heaped under water, the preservation of the matter against rapid decomposition is then the direct result of immersion. ”

“ The best coal produced in this field is from Indiana, where along the eastern border of it there is a good quality of block coal for furnace use, and some common bituminous coal of fair quality. The Illinois coal is all much inferior to that of Pennsylvania and Ohio, contains a portion of hygrometric moisture which lessens its heating power, and considerable sulphur and other injurious impurities. ”

“ The growth of the peat in cases of this kind may be stopped at the water level, where by a more complete decomposition of the plants a coat of humus is formed, which being invaded by land plants is transformed into a prairie or a forest.—But more generally peat grows above the water level, and then the production of the matter and its protection against the influence of the atmosphere are essentially due to the agency of a peculiar kind of moss, the sphagnum. ”

“ At some localities, especially in the upper part of the measures, it is softer and more easily broken; but at others the matter is hard, compact, distinctly laminated in thin alternate layers of crystalline and more opaque matter, gives much heat by combustion, the best kinds in some localities, as at San Pete in Utah, even producing good coke, and when the beds are in proximity to upraised dikes of basalt or lava the coal is transformed into anthracite. ”

“ As free bitumen does not exist in nature, deposits of bitumen in the rocks are an anomaly as long as the origin of bitumen cannot be positively indicated. Moreover, there is a great difference between bitumen, or rocks impregnated with bitumen, and coal beds. Hardened or oxidated bitumen has been found in a few instances filling crevices of rocks, as in Canada and in West Virginia ”

“ A basin of this kind is generally prepared in advance by the deposition of a clay bottom, produced from the decomposition of water plants or plants living entirely under water, whose tissue from this cause is not woody or fibrous; for the woody tissue of the plants is derived from the atmosphere, chiefly by the respiration of the leaves, and constitutes a part of the compound generally proportionate to the degree of humidity and the amount of carbonic acid of the atmosphere wherein they live. ”