Dora. When the two halves of the dining table came separate, yesterday, was that a 'fault'?
L. Yes; but not the table's. However, it is not a bad illustration, Dora. When beds of rock are only interrupted by a fissure, but remain at the same level, like the two halves of the table, it is not called a fault, but only a fissure; but if one half of the table be either tilted higher than the other, or pushed to the side, so that the two parts will not fit, it is a fault. You had better read the chapter on faults in Jukes's Geology; then you will know all about it. And this rent that I am telling you of in the Saléve, is one only of myriads, to which are owing the forms of the Alps, as, I believe, of all great mountain chains. Wherever you see a precipice on any scale of real magnificence, you will nearly always find it owing to some dislocation of this kind; but the point of chief wonder to me, is the delicacy of the touch by which these gigantic rents have been apparently accomplished. Note, however, that we have no clear evidence, hitherto, of the time taken to produce any of them. We know that a change of temperature alters the position and the angles of the atoms of crystals, and also the entire bulk of rocks. We know that in all volcanic, and the greater part of all subterranean, action, temperatures are continually changing, and therefore masses of rock must be expanding or contracting, with infinite slowness, but with infinite force. This pressure must result in mechanical strain somewhere, both in their own substance, and in that of the rocks surrounding them; and we can form no conception of the result of irresistible pressure, applied so as to rend and raise, with imperceptible slowness of gradation, masses thousands of feet in thickness. We want some experiments tried on masses of iron and stone; and we can't get them tried, because Christian creatures never will seriously and sufficiently spend money, except to find out the shortest ways of killing each other. But, besides this slow kind of pressure, there is evidence of more or less sudden violence, on the same terrific scale; and, through it all, the wonder, as I said, is always to me the delicacy of touch. I cut a block of the Saléve limestone from the edge of one of the principal faults which have formed the precipice; it is a lovely compact limestone, and the fault itself is filled up with a red breccia formed of the crushed fragments of the torn rock, cemented by a rich red crystalline paste. I have had the piece I cut from it smoothed, and polished across the junction; here it is; and you may now pass your soft little fingers over the surface, without so much as feeling the place where a rock which all the hills of England might have been sunk in the body of, and not a summit seen, was torn asunder through that whole thickness, as a thin dress is torn when you tread upon it.
(The audience examine the stone, and touch it timidly; but the matter remains inconceivable to them.)
Mary (struck by the beauty of the stone). But this is almost marble?
L. It is quite marble. And another singular point in the business, to my mind, is that these stones, which men have been cutting into slabs, for thousands of years, to ornament their principal buildings with,—and which, under the general name of 'marble,' have been the delight of the eyes, and the wealth of architecture, among all civilised nations,—are precisely those on which the signs and brands of these earth agonies have been chiefly struck; and there is not a purple vein nor flaming zone in them, which is not the record of their ancient torture. What a boundless capacity for sleep, and for serene stupidity, there is in the human mind! Fancy reflective beings, who cut and polish stones for three thousand years, for the sake of the pretty stains upon them; and educate themselves to an art at last (such as it is), of imitating these veins by dexterous painting; and never a curious soul of them, all that while, asks, 'What painted the rocks?'
(The audience look dejected, and ashamed of themselves.)
The fact is, we are all, and always, asleep, through our lives; and it is only by pinching ourselves very hard that we ever come to see, or understand, anything. At least, it is not always we who pinch ourselves; sometimes other people pinch us; which I suppose is very good of them,—or other things, which I suppose is very proper of them. But it is a sad life; made up chiefly of naps and pinches.
(Some of the audience, on this, appearing to think that the others require pinching, the Lecturer changes the subject.)
Now, however, for once, look at a piece of marble carefully, and think about it. You see this is one side of the fault; the other side is down or up, nobody knows where; but, on this side, you can trace the evidence of the dragging and tearing action. All along the edge of this marble, the ends of the fibres of the rock are torn, here an inch, and there half an inch, away from each other; and you see the exact places where they fitted, before they were torn separate; and you see the rents are now all filled up with the sanguine paste, full of the broken pieces of the rock; the paste itself seems to have been half melted, and partly to have also melted the edge of the fragments it contains, and then to have crystallised with them, and round them. And the brecciated agate I first showed you contains exactly the same phenomena; a zoned crystallisation going on amidst the cemented fragments, partly altering the structure of those fragments themselves, and subject to continual change, either in the intensity of its own power, or in the nature of the materials submitted to it;—so that, at one time, gravity acts upon them, and disposes them in horizontal layers, or causes them to droop in stalactites; and at another, gravity is entirely defied, and the substances in solution are crystallised in bands of equal thickness on every side of the cell. It would require a course of lectures longer than these (I have a great mind,—you have behaved so saucily—to stay and give them) to describe to you the phenomena of this kind, in agates and chalcedonies only;—nay, there is a single sarcophagus in the British Museum, covered with grand sculpture of the 18th dynasty, which contains in the magnificent breccia (agates and jaspers imbedded in porphyry), out of which it is hewn, material for the thought of years; and record of the earth-sorrow of ages in comparison with the duration of which, the Egyptian letters tell us but the history of the evening and morning of a day.