Carboniferous period

“ The same or similar beds are found in Siberia, in Japan, and in China, where the coal beds are said to be thicker than anywhere else in the world. The Carboniferous system is also found in Africa, in the north, south-east, and south of the continent; and in Australia and New Zealand Carboniferous strata to the thickness of 10,000 feet are indicated.
At the close of this period the changes ever taking place transformed the conditions of life in a way the reverse of that which we have hitherto been examining. So far each age has shown an increase of life on the age preceding it. ”

“ The Carboniferous period began with a marine transgression, enabling limestones to form in Tasmania and New South Wales; and at the same time the sea first got in along the western edge of the western plateau, depositing the Carboniferous rocks of the Gascoyne basin and the coastal plain of north-western Australia. The Upper Carboniferous period was in the main terrestrial, and during it were laid down the coal-seams of New South Wales; they are best developed in the basin of the Hunter river, and they extend southward, covered by Mesozoic deposits, beyond Sydney. ”

“ The purity of the coal, or its non-intermixture with earthy matter, presents another theoretical difficulty to many geologists, who are inclined to believe that the trees and smaller plants of the carboniferous period grew in extensive swamps, rather than on land not liable to be inundated. ”

“ In coal deposits of the Carboniferous Period their remains are not uncommonly found, and no essential structural difference has been discovered between these fossils and existing forms—a fact proving that the group has existed without material structural modification for untold thousands of years. ”

“ In our survey of the Carboniferous age, though there are peculiarities in the life of its older, middle, and newer divisions, we may take the great coal measures of the middle portion as the type of the land life of the period, and the great limestones of the lower portion as that of the marine life ”

“ The force, moreover, of the German critic's objection has been since in a great measure destroyed, by the larger and more profound knowledge acquired in the last few years of the ancient carboniferous flora, which has led the ablest botanists to adopt the opinion, that the climate of the coal period was remarkable for its warmth, moisture, equability, and freedom from cold, rather than the intensity of its tropical heat. ”

“ The very name Carboniferous originated in the fact that the rocks of this geologic period contain productive coal beds in so many parts of the world. The coal measures of Great Britain, of Germany, Belgium, and northern France, of Russia, and the largest coal beds of China are all of Carboniferous age. Deposits of this period include the bulk of the world's anthracite and high-grade bituminous coal. Coal deposits of more recent age are numerous, but in general they have had less time in which to undergo the processes of condensation and refinement, and hence their general grade is lower. ”

“ So abundant and varied are the sedimentary formations of Carboniferous time, and so fully have they preserved remains of the contemporary plants and animals, that it is not difficult to realise in some measure the general aspect of the scenery of the time, and the succession of changes which it underwent from the beginning to the end of the period. ”

“ Rarely are any large trunks or branches observable in the beds of coal; but the general appearance of the carboniferous mass is that of an immense deposit of delicate foliage shed and accumulated in a forest, and consolidated by great pressure while undergoing that peculiar process by which vegetable matter is converted into carbon. ”

“ During the earlier ages (Silurian and Devonian) of this Palæozoic era, the place of the Appalachian chain of mountains was marginal sea bottom; but during the later ages (Carboniferous) it was, through repeated oscillations, in an uncertain state, being sometimes swamp land, sometimes covered with river sediment, and sometimes covered by the sea. It was during this Carboniferous age that the great coal measures were formed; at this time also the climate was probably very uniform, warm and moist, loaded with carbonic acid gas and deficient in oxygen. ”

“ Some features of the condition of the earth during the deposition of the carboniferous group, are made out with a clearness which must satisfy most minds. First we are told of a time when carbonate of lime was formed in vast abundance at the bottoms of profound seas, accompanied by an unusually large population of corals and encrinites; while in some parts of the earth there were patches of dry land, covered with a luxuriant vegetation. ”

“ That age of the world’s history which, from its richness in accumulations of vegetable matter destined to be converted into coal, has been named the Carboniferous, is in relation to living beings the most complete and noble of the Palæozoic periods. ”

“ If you like, on the other hand, to be scientific you will listen to those who tell you that instead of there having been one unique carboniferous epoch, with a peculiar coal-making climate, all epochs are carboniferous if they get the chance; that coal is of every age, from that of the Scotch and English beds, up to the present day. The great coal-beds along the Rocky Mountains, for instance, are tertiary—that is, later than the chalk. ”

“ About 100 forests have successively grown, partially decayed, and been entombed in muddy and sandy sediment. In the same section, including in all about 14,000 feet of beds, there are 76 seams of coal, each of which can be proved to have taken more time for its accumulation than that required for the growth of a forest. Supposing all these separate fossil soils and coals to have been formed with the greatest possible rapidity, forty thousand years would be a very moderate calculation for this portion of the Carboniferous system ”

“ The waters had now brought forth abundantly the moving creatures, which, at first more scantily distributed, produced the limestone of the silurian rocks, as the arborial remains of the land, in like stinted measure, are inclosed in the older palæozoic deposits. Their day of increase as it advanced, each after their kind, is recorded in the vast accumulations [100] of animal and vegetable matter which compose the strata of the carboniferous system, both of an order and quality purposely so arranged, and never upon the same scale of magnitude to be repeated in the combustible mineral. ”

“ It was, that the water flowing over the ground should bring with it and leave in the bottom of the basin where the carboniferous matter was destined to accumulate, only the remains of plants, to the exclusion of every other form of sediment. This condition may have been more easily realized in the Carboniferous epoch than at any other time, because the flora was more abundant and its extension more favored by the climate. ”

“ But equally certain it is, I repeat, that wherever carboniferous formations have been discovered and examined, they have been found to bear the unique characteristic to which the system owes its name,—they have been found charged with the carbon, existing usually as great beds of coal, which was elaborated of old by its unrivalled flora from the elements. ”

“ The carboniferous series is so named because it is the earliest and most important coal-bearing series of strata, and includes great beds of fossil fuel, interstratified with sandstones and shales. At the base of the carboniferous in Michigan, Pennsylvania, and western Virginia, and also in Nova Scotia and New Brunswick, deposits of gypsum and salt are met with. In the western part of its distribution, toward the Mississippi, the carboniferous formation includes great thicknesses of marine limestone, which are wanting in the east. ”

“ In a word, all the indications suggest the early and middle Carboniferous as an age of vast swamps, of enormous stretches of land just above or below the sea-level, and changing repeatedly from one to the other. ”

“ Now, though Geology cannot tell if we shall succeed in finding Coal beneath these rocks, it can tell if there is a good chance of succeeding. It can tell whether there is a reasonable hope, by penetrating into the Crust of the Earth at this particular spot, of reaching the Carboniferous Formation; and if we can reach the Carboniferous Formation in the midst of a Coal district, it is very likely we shall meet with beds of Coal. ”

“ And as this evidence is certain and positive, no one would be entitled to set off against it, as of equal weight, the merely negative evidence of some one or two deposits of the carboniferous age that did not bear the carboniferous character, even were such known to exist; far less is anyone entitled to set off against it the possibly negative evidence of deposits of the carboniferous age not yet discovered nor examined ”

“ If it be a Formation earlier in date than the Carboniferous,—the Silurian, for instance, or the Devonian,—he knows that it would be simply waste of money to look for Coal beneath them; because the Carboniferous rocks cannot possibly be found underneath the rocks of an earlier age. ”

“ Observations of geological strata indicate an increase of carbon in the crust of the earth since the earliest times, for the rocks of the older formations contain less of it than those of the carboniferous and succeeding ones. ”

“ Principal Subdivisions of the Carboniferous Group.—The next group which we meet with in the descending order is the Carboniferous, commonly called “The Coal,” because it contains many beds of that mineral, in a more or less pure state, interstratified with sandstones, shales, and limestones. The coal itself, even in Great Britain and Belgium, where it is most abundant, constitutes but an insignificant portion of the whole mass. ”

“ Though there is great diversity in the Carboniferous coals, and it would be absurd to express their composition by a single formula, it may be said that, over the whole world, these coals have characteristics, as a group, by which they can be recognized, the result of the slow decomposition of the tissue of plants which lived in the Carboniferous age, and which have, by a broad and general change, approximated to a certain phase in the spontaneous distillation of plant-tissue. ”

“ Succession and Thickness of Strata.
Considered in its greatest generality, and with reference to countries where the masses appear in the greatest simplicity (as in the south of England) , the carboniferous system consists of three formations: viz.—
Coal formation. ”

“ In the north of England, for example, the thickness of the coal-bearing strata has been estimated at 3000 feet, while the various coal-seams, 20 or 30 in number, do not in the aggregate exceed 60 feet. [308-A]
The carboniferous formation comprises two very distinct members: 1st, that usually called the Coal-measures, of mixed freshwater, terrestrial, and marine origin, often including seams of coal; 2dly, that named in England the Mountain or Carboniferous limestone, of purely marine origin, and containing corals, shells, and encrinites. ”

“ II. Origin of the Carboniferous Rocks.—The strata comprised within the coal-measures are variously estimated; being, in some instances, about eleven thousand feet in thickness; in other cases, of much greater depth; and of this mass of matter, the coal itself does not occupy more than a maximum average of one hundred and fifty feet. The shales consist of thin beds of mud, washed down by the rivers from the neighboring heights, and would appear to have formed the soil on which subsisted a rank vegetation ”

“ It seems strange to one who derives his supply of domestic fuel from the Dalkeith and Falkirk coal-fields, that the Carboniferous flora could ever have been described as devoid of trees. I can scarce take up a piece of coal from beside my study fire, without detecting in it fragments of carbonized wood, which almost always exhibit the characteristic longitudinal fibres, and not unfrequently the medullary rays. ”

“ The carboniferous class of rocks have all the marks of a very peculiar formation, constructed for a special purpose, and elaborated amidst an extraordinary state of things. Here we meet with vast accumulations of vegetable, calcareous, and metallic substances, for which we detect no anterior preparations. The coming on and the outgoing of the whole coal series are as distinct as they are surprising. ”

“ Strata of Carboniferous age have been discovered in almost every large land-area which has been sufficiently investigated; but they are especially largely developed in Britain, in various parts of the continent of Europe, and in North America. Their general composition, however, is, comparatively speaking, so uniform, that it will suffice to take a comprehensive view of the formation without considering any one area in detail, though in each region the subdivisions of the formation are known by distinctive local names. ”

“ It would be easy to calculate in how short a period the solid carbon, thus emitted from the interior of the earth in an invisible form, would amount to a quantity as great as could be obtained from the trees of a large forest, and how many thousand years would be required to supply the materials of a dense seam of pure coal from the same source. ”