CHAPTER III.THE ANCIENT EPOCH.

“Where wast thou when I laid the foundations of the earth?”—Jobxxxviii. 4.

And now in right earnest let us begin our examination of the earth’s crust. Some of the terms we may use will, perhaps, at first sight appear repulsive from their novelty and difficulty; such words we will explain as we proceed, and will only stay the student’s course to remark, that there is a necessity for the use of the dead languages in the formation of compound terms that are to become descriptive names, and in their application to newly discovered objects. This necessity arises from the fact that it is only in this way that scientific men of different nations can understand the character of each other’s researches, and compare notes with one another. A fossil is found, let us suppose, in the lias formation; it proves to be the organic remainsof some very strange and anomalous creature. People go down to Lyme Regis to examine it, and, in doing so, discover others. Comparative anatomists arrange the dislocated parts and give them a name; this must be intelligible to geologists on the Continent as well as in England; and therefore some term descriptive of the animal, once the living possessor of these “dry bones,” must be given, and finally it is calledichthyosaurus. Any one in Russia, or Austria, or Italy, who happened to be acquainted with the rudiments of Greek, would know at once the kind of animal referred to by its very name, derived fromichthus, a fish, andsauros, a lizard. This would indicate to all scientific men the nature of this remarkable animal, of which we shall have to tell some stories by and by as full of wonder as any modern or ancient book of marvels; while, if we had called itfish-lizard, only those who understood English would know what we meant. Our object is to simplify as much as possible every difficult term that may be used; but while we solicit our readers to master each difficulty as it rises, we hope they will not think that, when they have read this little book, they are masters ofGeology, our highest ambition being only to impart atastefor the science.

To return: our examination commences with the Plutonic rocks, so called in memory of the well-known mythological god of the fiery or infernal regions; and we takegranite[14]as a type of these rocks, because it is so familiar to all our readers. There are besides granite, syenite,[15]greenstone, porphyry, basalt, and others, to dilate upon which would defeat our purpose. Our object is to lay but a little at a time upon the memory, and to let that little be well digested before we pass from the thoroughly known to the unknown. Nothing but actual examination can make the student familiar with the varieties of the rocks of this very ancient epoch in the world’s history. Well, everybody knows what granite is; they see it on the kerb-stones of the wayside, in the hard paving of the London streets, in the massive slabs of London and Waterloo Bridges, and elsewhere. “Granite!” exclaims the reader, “everybody knows what granite is, and there is an end of it; you make as much fuss about granite as Wordsworth didabout his well-known primrose, and the man who could see nothing but a primrose in a primrose.”

But there is a poetry and a history about granite upon which we are going to dwell. This piece of granite which I hold in my hand is composed of quartz, mica, and feldspar.[16]The quartz is white and hard—I can’t scratch it with my knife; the mica is in glistening plates or scales; and the feldspar is soft and greyish, and can easily be scratched. Oh, if this granite could speak, what a story could it tell! “To give it, then, a tongue were wise in man.” Let us try. “Once upon a time, long, long ages ago, incalculable periods before Adam was placed in possession of Eden, I, the granite, and my contemporaries, came into being. Before us, this planet ‘was without form and void.’ A dark chaotic period, of which I know nothing, preceded me. When I first emerged into being, at the command of Him who laid the foundations of the earth, this world was a barren, lifeless, uncultivated, uninhabited, untrodden, seasonless waste. Here and there were undulations of land and water,but all was bare, desolate, and silent: not a moss nor a lichen covered the ancient skeleton of the globe; not a sea-weed floated in the broad ocean; not a trace existed even of the least highly organized animal or vegetable; everything was still, and with the stillness of universal death. The earth was prepared, and the fiat of creation had gone forth; but there was no inhabitant, and no beings endowed with life had been introduced to perform their part in the great mystery of creation.”[17]And the granite might go on to say—“Man! of three-score years and ten, where wastthouwhen He, my Maker and yours, laid the foundations of the earth? Let me tell you what an important part I have played in the history of your world’s formation. I rise to the highest elevations, and form the sublimest pinnacles on the surface of the globe, and without me your scenery would lose its grandeur and its glory. But for me Albert Smith had never climbed Mont Blanc, nor Humboldt Cotopaxi and Chimborazo; nor would the head of the famed Egyptian Memnon[18]have been sculptured. You may see me giving to Cornwall, Wales, and Scotland their most valuable minerals and metals. In Europe

‘I am monarch of all I survey,My right there is none to dispute.’

‘I am monarch of all I survey,

My right there is none to dispute.’

The Scandinavians, the Hartz mountains, the Alps, and the Pyrenees are mine; nor is my territory less in Asia, Africa, the great Americas, and in the becoming great Australia; and thus, by my deeply rooted foundations and my vast extension, I constitute the framework, solid and immoveable, of this ‘great globe and all that it inherits.’”

Thus, at any rate, the granite might speak, nor would there be one word of vain boasting in it. Having beard it, or fancied we heard it, which amounts to the same thing, let us soberize ourselves, and put granite into the third person. There are no fossils in granite and the other Plutonic and volcanic rocks; even supposing any forms of life to have been in existence at the period to which we are referring, the action of fire has annihilated all their remains. We should not therefore expect in Cumberland and Cornwall, nor in those parts of Devonshirewhere granite prevails, to find the fossils peculiar to other formations with which in time we hope to make familiar acquaintance. But though destitute of interest in this respect, how great is its importance and interest in those economic uses which have the geologist for their guide, and the whole family of man for their beneficent operations! “Many varieties of granite are excellent as building stones, though expensive in working to definite forms. Some of the most important public works of Great Britain and Ireland, France and Russia, are of this material. In selecting granite, those varieties in which the constituent minerals and the scales of mica are superabundant, should be avoided; and, as a practical test, it is wise to notice the country immediately around the quarry, as the sandy varieties rapidly disintegrate,[19]and form accumulations of micaceous sand. The Hayter or Dartmoor granite, the Aberdeen granite, the Kingstown (Dublin) granite, some beds of the Mourne or county of Down granite, and the Guernsey or ChannelIsland granite, are well known for their excellence. In some of the quarries the bedding of the granite is more defined than in others; and wherever this is the case, or where marked cleavages or joints prevail, the work is much facilitated. Many old Egyptian works and statues were formed of granite, and it is still used for colossal works, as it takes a fine polish. For example, the great fountain shell, or vase, before the Museum at Berlin, and the pedestal of Peter the Great at St. Petersburg, are of the northern granite, being sculptured from erratic blocks. The splendid Scotch granite columns, in the vestibule of the Fitzwilliam Museum at Cambridge, are beautiful examples of a modern application of this rock to the arts.”[20]

It is also in the Plutonic or igneous rocks that almost all the metals are found; and here we have our first illustration of that order to which we shall frequently call attention; an order as exquisite as can be found in the drawers of a lady’s cabinet, forbidding the thought that anything observable at the present time, in the bowels or on the surface of the crust of the earth, can be attributed to theviolent diluvial action of the Noachian deluge. The diagram below represents an ideal section of a mining district.

SECTION OF A MINING DISTRICT.

Here the metalliferous vein, we may suppose, has cropped out on the surface of the ground, or, as the miners say, has “come above grass.” Let us now suppose that the position of this vein of ore, copper, lead, or tin, has been ascertained—that is, how it runs, whether from north to south, or from east to west—and also that the “captains” of the mining district around have given their opinion as to the extent and thickness of this underground vein. The next thing is to obtain this mineral wealth.For this purpose shafts (a a a a) must be sunk, which must reach the vein at a certain depth; then will probably follow cross-cuts (c c c), called adit levels (technically an “additt”), driven, as may be seen, at the lowest convenient point above the level of the highest water of the valley; and these, in connexion with the shaft, will serve the purpose of draining the mine and carrying the ore above ground. It will also be seen, by reference to the diagram, that the shafts of a mine do not always correspond; sometimes they are sunk vertically to meet the vein, sometimes they are commenced in the very outcrop itself. On this matter the best geological lesson is a visit to Cornwall, where the student will see that everything depends on the locality of a mine, the nature of the slope of the hill, or the character of the rock in which the vein appears, and so on. “The act of sinking a perpendicular shaft downwards to a depth where it is calculated the lode should be cut, may seem to require little further skill than is necessary to determine correctly the spot on the surface where the work is to commence. But the process in this way is exceedingly tedious; and in a mine at work,where many galleries already existing are to be traversed, much greater rapidity is desirable. In such a case the shaft is sunk in severalpieces(see diagram below), or, in other words, the sinking is commenced at the same time in different levels; and no small skill is required to lay out the work, so that the different portions of the shaft thus formed may exactly fit when they are joined together. An exceedingly small error of measurement, in any one of these various and dark subterranean passages, would, in fact, be sufficient to throw the whole into confusion; but such an accident rarely happens, although works of the kind are common in the Cornish mines.”[21]As an illustration of the immense quantity of water in the mines, we may add—and this is almost as startling as any romantic fiction—that the various branches of the principal level in Cornwall, called “the Great Adit, which receives the waters of the numerous mines in Gwennap, and near Redruth, measure on the whole about 26,000 fathoms, or nearly thirty miles in length; one branch only, at Cardrew mine, extends for nearly five miles and a half, and penetrates ground seventy fathoms beneath the surface. The water flows into a valley communicating with a small inlet of the sea, and is discharged about forty feet above high-water mark.”[22]In this method about forty millions of tons of water are raised by steam-power out of the mines in Cornwall.

EAST WHEAL CROFLY COPPER MINE, CORNWALL.

Here, then, we have seen two of the economic uses of geology in connexion withgranitealone; and as we think of these mineral treasures, requiring only the labour and skill of man to bring them out for his service and for the civilizationof the world, our boast is in our native land, which, though insular and small, combines within itself everything needful to develop its three sources of national wealth—mining, manufactures, and agriculture—to their highest point. Our boast is not the warrior’s boast, which Shakspeare puts into the mouth of one of his heroes—that this our isle is

“That pale, that white-faced shore,Whose foot spurns back the ocean’s roaring tides,And coops from other lands her islanders”—

“That pale, that white-faced shore,

Whose foot spurns back the ocean’s roaring tides,

And coops from other lands her islanders”—

but rather that, without impropriety or irreverence, the words of Holy Writ may as legitimately be applied to Great Britain as to Palestine. It is a land wherein “thou shalt eat bread without scarceness, thou shalt not lack anything in it; a land whose stones are iron, and out of whose hills thou mayest dig brass.[23]When thou hast eaten and art full, then thou shalt bless the Lord thy God for the good land which He hath given thee.” (Deut. viii. 9, 10.)

But before we bring this chapter on granite and its kindred rocks to a close, we must glance at one more purpose served by this Plutonic rock. Here is a teacup, and here is a piece of granite: the one comes from Cornwall, the other is made in Staffordshire or Worcestershire. What relation have they to each other? If it were not thoughtinfra dig., we should say the granite is the parent of the teacup. In Cornwall, especially in the neighbourhood of St. Austel, the writer has lately visited what are called the China clay works. “The granite is here in a state of partial decomposition. In some localities, thisgrowan” (Cornish for disintegrated granite) “is tolerably firm, when it resembles the ChineseKaolin, and, quarried under the name of China stone, is extensively employed in the potteries. This is ready for the market when cut into blocks of a size convenient for transport; but the softer material, which is dug out of pits, and calledChina clay, orporcelain earth, requires a more elaborate preparation for the purpose of separating the quartz, schorl, or mica from the finer particles of the decomposed feldspar. This clay is dug up instopesor layers, which resemble a flightof irregular stairs. A heap of it is then placed upon an inclined platform, under a small fall of water, and repeatedly stirred with apiggleand shovel, by which means the whole is gradually carried down by the water in a state of suspension. The heavy and useless parts collect in a trench below the platform; while the China clay, carried forward through a series ofcatch-pitsor tanks, in which the grosser particles are deposited, is ultimately accumulated in larger pits, calledponds, from which the clear supernatant water is from time to time withdrawn. As soon as these ponds are filled with clay, they are drained, and the porcelain earth is removed topans, in which it remains undisturbed until sufficiently consolidated to be cut into oblong masses. These are carried to a roofed building, through which the air can freely pass, and dried completely for the market. When dry they are scraped perfectly clean, packed in casks, and carried to one of the adjacent ports, to be shipped for the potteries.”[24]As furnishing some idea of the extent to which this business is carried on, it may be added that 37,000 tons of this China clay are annuallyshipped from the south-west of England to the potteries, the value of which is upwards of £50,000, while the number of working men and women thus employed is beyond calculation. This is one of the practical results of geology. This is one of the things which geology, once a neglected and unpopular science, has done for our comfort and welfare. “A hundred years ago, it does not seem that any part of this China clay was made use of, or that this important produce was then of any value whatever.”[25]

We bring this chapter to a close. Granite and its kindred rocks should stand associated with an actual history and poetry, not inferior to the history and poetry of man’s own handiwork; and we believe geology, so often regarded with dread by the uninitiated, will soon be considered worthy a patient and painstaking investigation. Remembering that geology is still an incomplete science, and that we have much yet to learn concerning the laws of organic and inorganic matter, we should be modest in the maintenance of any theory, while thankful for the acquisition of any fact. “We have yet to learn whether man’s past duration upon the earth—whethereven that which is still destined to him—is such, as to allow him to philosophise with success on such matters; whether man, placed for a few centuries on the earth as in a schoolroom, has time to strip the wall of its coating and count its stones, before hisParentremoves him to some other destination.”[26]

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