No quadruped or true terrestrial animal is found so low in the series of rocks, or mixed up in any way with all this profusion of marine exuviæ. Fossil insects and indications of other winged tribes have been detected; but no bone nor foot-print of beast, or inhabitant of land, has anywhere been discovered. The fact is all-important, as showing not only a plan, but a progress and succession in the work of creation. A vegetation, so rank and luxuriant as has been traced, trees towering hundreds of feet into the sky, and branches of the densest foliage stretching on every side, was amply fitted to afford shelter and food to families of terrestrial creatures of every kind. But in the circumstance, that during this period there were repeated alternations of marine and fresh water deposits, and consequently repeated submergence and elevation of land, we see a reason why the terrestrial races were not yet called into being. Great continents, comparatively speaking, did not exist; and there was no ark of safety provided to float them over the billows. Race after race would have violently perished during every shift or subsidence of the sea bottom: and hence, until the carboniferous series was completed and a statical equilibrium established between the land and waters, few or none of the races which afterward swarmed in our plains and forests were introduced upon the scene.

CHAPTER VIII.

GEOGRAPHICAL DISTRIBUTION OF COAL-GREAT COAL FIELD OF PENNSYLVANIA, VIRGINIA AND OHIO-COAL DEPOSITS OF ILLINOIS, INDIANA AND KENTUCKY — ECONOMIC HISTORY-CONDITIONS OF FORMATION.

CONSIDERED mineralogically, and now demonstrated beyond a doubt, coal and the diamond are found to be one and the same in substance, and nearly also in their modes of formation. Newton detected the properties of the diamond in its refractive power over the rays of light, and inferred that, like amber, it was an unctuous body crystallized. In the crucible he reduced it to a state of pure carbon, burning, volatilizing, and resulting in the same elementary products as charcoal. Liebig goes a step farther, and declares the diamond to be a crystalline residuum from decayed vegetables. The action of fire could not produce the mineral, but would rather have the effect of drawing out its inflammable tendencies. "Science," he adds, "can point to no process capable of accounting for the origin' and formation of diamonds, except that of decay. And there is the greatest reason for believing that they have been formed in a liquid.” Sir David Brewster, in his beautiful optical analysis, has arrived at the same general conclusions.

Coal is also a product of vegetable decay, collected and formed in a liquid. It has not crystallized, and therefore wants the sparkle and the luster of the diamond. It retains all the carbon, and more of the hydrogen, and is in consequence infinitely more useful and valuable than even the precious gem. It is carefully incased and preserved among the rocks of the earth, and thereby in like manner akin to the glittering idol, whose true habitat has

been found to be the sandstones immediately overlying the carboniferous formation. Thus far the parallel can be traced between the two apparently very dissimilar and unequally prized minerals in extent of substance and geographical distribution, the history of each stands apart.

I. THE GEOGRAPHICAL DISTRIBUTION OF THE COAL METALS. Our knowledge on this subject is increasing with every new geographical detail connected with the history of the earth. Until very recently the carboniferous system was supposed to be of very limited extent. The return of every vessel, engaged in a voyage of discovery or otherwise, brings tidings of some new island or continent on which it is found. The same tribes of plants and animals are everywhere observed to accompany the deposit—all presenting the same generic and often the same specific characters and uniformly on the same great scale of development. This circumstance alone bespeaks a universal formation, when every region was capable of producing all the requisite conditions in climate, vegetables, corallines, and sea-bottom, and prepares the mind for the ready admission of the existence of the mineral in every unexplored quarter of the globe. Accordingly, all the great continents of the old world abound in coal. In Russia, the carboniferous system occupies, betwixt the Dnieper and the Don, an area of about eleven thousand square miles. India, China, and the Australian archipelago give up yearly more and more of the bituminous substance. Egypt is not destitute of the jetty mineral for recently beds several feet thick have been discovered near Asuan, on the right bank of the Nile. The vast continent of America has it in proportion to its own vastness. And man, go where he will with the knowledge of the arts, and the diffusive blessings of religion and civilization, will always find that a wise

* The diamonds found in the Ural chain are supposed to be connected with the carbonaceous grits of the devonian and carboniferous periods, which have been transmuted into metamorphic micaceous rocks, and contain the diamonds between the flakes of mica, just as garnets occur i mica-schist. Captain Franklin discovered diamonds in Bundelkund, imbedded in sandstone, with coal beneath, and supposed to belong to the true carboniferous system.

Providence has anticipated his wants, and prepared the treasure for his use.

The coal formation in Scotland has been already traced as occupying the great central valley of the Lowlands, which separates the primitive crystalline and feldspathic rocks of the north from the silurian series of the southern border, and traversing the mainland from sea to sea. The middle and northern coal basins of England have an average uninterrupted stretch of about two hundred miles in length, by forty in breadth. The Bristol and Welsh coal-fields, are also very extensive. That of South Wales forms an immense double trough, comprised within a great oval elongated tract, betwixt St. Bride's Bay, and Pontypool, with an anticlinal axis ranging east and west, and embracing an area of one thousand and fifty-five square miles. This is the largest coalfield in Britain, in which there are sixty-four seams of coal, of all qualities, from the highest bituminous to the purest anthracite, and having an aggregate thickness of one hundred and ninetyfeet. In Ireland the coal basins are comparatively small, and isolated from one another: the principal workable seams are in the counties of Kilkenny, Tipperary, Cork, Tyrone, and the northern extremity of Roscommon.

The coal metals immediately present themselves on the French coast at Boulogne, more inland at Mons, and in the central district at St. Etienne, betwixt the valleys of the Loire and Rhone. This last basin is of small extent, but possesses great geological interest from its position among the primary and metamorphic rocks, and the materials of which the series is composed. The metals are inclosed in a long narrow trough, of about twenty-five miles by less than a mile at its greatest breadth. Granite, gneiss, mica-slate, underlie them throughout: instead of shales, and sandstones of the usual kind, the coals are imbedded in micaceous grit, and the detrital alluvia of the crystalline rocks. It has been described as a self contained repository, with its own furnishings and equipments all, as it were, self-originating: the vegetable matter is of native growth, the trees are still vertical, and in one part of the field present the appearance of a suddenly petrified forest; the iron, too, is native, and seems to have been actually smelted on the spot, by subterranean self-com

bustion. The coal, underlying one of the bands of ironstone, has undergone fusion, and been changed into coke; while sulphur and crystals of sulphate of lime have been separated in the crucible by the process of sublimation, as if to complete this scene of marvels. In the low countries, at Namur and Liege, and other places along the banks of the Meuse-in Germany, Silesia, Moravia, Poland, the Carpathian Mountains-on the banks of the Volga, the Dnieper, and the Don, the coal-measures are found to occupy tracts of greater or lesser extent. These are sometimes accompanied with the usual alternating series entire and unbroken, sometimes with the absence of one or more members. In Russia the metals are imbedded in the middle mountain limestone series in one field, while in another district they are situated in the lower part of the series, or beneath the calcareous deposit, as in the thin beds of Fifeshire. The Liege coal-basin is of a remarkably complex structure-the metals lying in small hollows of contorted strata, which are bent and twisted like a sapling—elevated into every varying position and degree of inclination-and thus, by obtaining cross or horizontal sections, you pass repeatedly over the edges of the same beds. An enterprising Scotchman has long been lessee of one of these coal-fields, out of whose iron bands he has molded cannon and ball for every nation in Europe; and whose locomotives, forged from the same strata, now ply in pleasure excursions along every railway of the Netherlands and vine-clad banks of the Rhine and Moselle.

The American coal-fields, like its interminable forests, endless rivers, and everything in that vast continent, are all on the gigantic scale. The basin of the Mississippi, extending from the Rocky Mountains to the Alleghanies, forms an area equal to two-thirds of the states of Europe, almost every part of which is covered with the carboniferous limestone, supporting the coal metals and the newer palæozoic rocks. The great coal-field of Pennsylvania, Virginia, and Ohio, extends, according to Sir Charles Lyell, continuously from north-east to south-west for a distance of 207 miles, its breadth being in some places 180 miles. The basin of Illinois, Indiana, and Kentucky, is not much inferior in dimensions to the whole of England, while another coal deposit, 170 by 100 miles, lies farther to the north, between lakes Michigan and Huron.