If coal, like other mineral strata, have been inspissated and consolidated by subterranean heat, we should find them traversed with veins and fissures; and, if the matter found in those veins and fissures corresponds to that found in similar places of other strata, every confirmation will be hence given to the theory that can be expected from the consideration of those bituminous strata.  But this is the case; we find those fissures filled both with calcareous, gypseous, and pyritous substances.  Therefore, we have reason to conclude, that the strata of fossil coal, like every other indurated or consolidated body in the earth, has been produced, first, by means of water preparing and collecting materials proper for the construction of land; and, secondly, by the operation of internal fire or subterranean heat melting and thus consolidating every known substance of the globe.

Not only are those sparry and pyritous substances, which are more natural to coal strata, found forming veins traversing those strata in various directions, but also every other mineral vein may occasionally be found pervading coal mines, or traversing bituminous strata.  Gold, silver, copper, lead, calamine, have all, in this manner, been found in coal.

There remains now only to consider those bituminous strata of fossil coal in relation to that change of situation which has happened more or less to every stratum which we examine; but which is so much better known in those of coal, by having, from their great utility in the arts of life, become a subject for mining, and thus been traced in the earth at great expense, and for a long extent.

Coal strata, which had been originally in a horizontal position, are now found sometimes standing in an erect posture, even almost perpendicular to the plane in which they had been formed.  Miners therefore distinguish coal strata according as they deem them to approach to the one or other of those two extremes, in terming them either flat or edge seams or veins.  Thus, it will appear, that every possible change from the original position of those strata may have happened, and are daily found from our experience in those mines.

But besides the changed position of those strata, in departing from the horizontal line or flat position in which they had been formed, there is another remarkable change, termed by miners a trouble in the coal.  The consideration of this change will further illustrate the operations of nature in placing that which had been at the bottom of the sea above its surface.

Strata, that are in one place regularly inclined, may be found bended, or irregularly inclined, in following their course.  Here then is a source of irregularity which often materially effects the estimates of miners, judging from what they see, of those parts which are to be explored; and this is an accident which they frequently experience.

But, without any change in the general direction of the stratum, miners often find their coal broke off abruptly, those two parts being placed upon a higher and lower situation in respect to each other, if flat beds, or separated laterally if they are edge seams.  This is by miners termed a slip, hitch, or dyke.