56. The immense violence which has accompanied the formation of mineral veins, is particularly marked by the slips and shifts of the strata on each side of them all tending to show what mighty changes have taken place in those regions, which our imagination erroneously paints as the abode of everlasting silence and rest. This shifting of the strata is best observed, where the veins make a transverse section of beds of rock, considerably inclined to the horizon. There it is common to see the beds on one side of the vein slipped along from the corresponding beds on the other side, and removed sometimes in a horizontal, sometimes in an oblique direction. In this way, not only the strata are shifted, but veins, which intersect one another, are also shifted themselves. They are _heaved_, as it is called in the significant language of the miners, and forced out of their direction. It is impossible, in such a case, but to connect in the mind the formation of the vein, and the production of the slips which accompany it, and to regard them as parts of the same phenomenon. 57. Where these slips are horizontal, and exhibit great bodies of strata carried from their place, while the parts of the transferred mass remain undisturbed relatively to one another, they furnish a dear proof, that this change of plaice has not arisen from the falling in of the roofs of caverns, as some geologists suppose. The horizontal direction, and the regularity of the movement, are incompatible with the action of such a cause as this; and indeed it is highly interesting to remark, in the midst of the signs of disturbance which prevail in the bowels of the earth, that there reigns a certain symmetry and order, which indicate the action of a force of incredible magnitude, but slow and gradual in its effects. The parts of the mass moved are undisturbed relatively to one another; what has been broken has been cemented; the breaches of continuity have been filled up and healed; and every where we see the operation of a cause that could unite as well as separate. The twofold action of heat to expand and to melt, could scarce be pointed out more clearly by any system of appearances. 58. As a long period was no doubt required for the elevation of the strata, the rents made in them are not all of the same date, nor the veins all of the same formation. This is clear in the case of one vein producing a shift or slip in another; for the vein which forces the other out of its place, and preserves its own direction, is evidently the more recent of the two, and must have had its materials in a state of activity, when those of the other were inert. Sometimes, also, at the intersection of two veins, we may trace the current of the materials of the one, across those of the other; and here, of consequence, the relative antiquity is determined just as in the former instance.