Vegetation becomes scarce in this region, not, as commonly supposed, because Alpine plants do not here find the necessary conditions for growth, but simply for want of soil. The intense heat of the direct rays of the sun (see chapter iii., pages 76-77) compensates for the cold of the night; and it is probable that the greater allowance of light also stimulates vegetable life. But all the more level parts are covered with ice or snow; and the higher we ascend, the less the surface remains bare, with the exception of the projecting rocks which usually undergo rapid destruction and breaking up from the freezing of whatever water finds its way into their fissures.

Nevertheless, many species of flowering plants have been found even at the height of eleven thousand feet.

It is in this region that plants are found whose true home is in the arctic regions (see chapter ii., pages 64-65).

For the sake of those who love ferns, lycopods, and other cryptogamic or flowerless plants, a few words may be said here. Of the polypodies, the beech fern and oak fern are generally common, so is the limestone polypody in places where limestone occurs. Another species (P. alpestre) very like the lady fern grows plentifully in many places. The parsley fern, familiar to the botanist in Wales and other parts of Great Britain, is common, especially on the crystalline rocks, and ascends to above seven thousand feet. The holly fern is perhaps the most characteristic one of the higher Alps. It is abundant in almost every district from the Viso to the Tyrol, ranging from about five thousand feet to nearly eight thousand feet. The finest specimens are to be found in the limestone districts. Nestling down in little channels worn out of the rock, it shoots out great fronds, often more than eighteen inches long, which are giants compared to the stunted specimens seen on rockwork in English gardens.

Asplenium septentrionale is very common in most of the districts where crystalline rocks abound. The hart's tongue is hardly to be called a mountain fern. The common brake is confined to the lower slopes.

Cistopteris fragillis and C. dentata are common, and the more delicate C. Alpina is not rare. The noble Osmunda regalis keeps to the warmer valleys. The moonwort abounds in the upper pastures.

The club-mosses (Lycopodium), which are found in Great Britain, are common in most parts of the Alps, especially the L. selago, which grows almost up to the verge of the snows. Lower down is the delicate L. velveticum, which creeps among the damp mosses under the shade of the forest. Many of the smaller species stain with spots of crimson, orange, and purple the rocks among the snowfields and glaciers, and gain the summits of peaks more than eighteen thousand feet above the sea, reaching even to the highest rocks in the Alpine chain. For the sake of readers who are not familiar with that wonderful book, "Modern Painters," we will quote some exquisite passages on lichens and mosses, full of beautiful thoughts:—

Alpine and arctic plants are met with in Great Britain, but Scotland has a much more extensive arctic-Alpine flora than England, Wales, or Ireland, the reason being the greater altitude of its mountains. The combined flora of the United Kingdom contains only ninety-one species of arctic-Alpine plants, and of these eighty-eight—that is, all but three—are natives of Scotland. Of these three the first is a gentian (Gentiana verna), which is to be found on the hills of West Yorkshire, Durham, Westmoreland, and other parts. It comes from the Alps. The second is Lloydia serotina,—a small bulbous plant with white flowers, which is found on the hills of Carnarvonshire, in Wales. The third, well known in English gardens, is London pride (Saxifraga umbrosa), which is only to be found on the southwest Irish hills.

Of the ninety-one arctic-Alpine species, just about half are also natives of England and Wales, but only twenty-five belong to Ireland. If we examine the lists of the flora of Arctic Europe we find that all these, except about six, are found in arctic regions; and if we travel farther north till we come actually to polar regions, we find nearly fifty of these species growing there near the sea-level. The Grampian Mountains are the chief centre of the Scottish arctic-Alpine flora. The two principal localities for such flowers in that range are the Breadalbane Mountains in Perthshire, and the Cænlochan and Clova Mountains of Forfarshire. There are also a goodly number on the mountains of the Braemar district.

The history of the arctic-Alpine flora of Europe is a very interesting one. These plants, whose true home is in the arctic regions, living high up on the mountains of Europe, give unmistakable evidence of a time, very far back, when Northern Europe was overrun by glaciers and snowfields so as to resemble in appearance and in climate the Greenland of the present day. This period is known to geologists as the "Great Ice Age." The moraines of glaciers, ice-worn rock surfaces, and other unmistakable signs may be well seen in many parts of Great Britain. How long ago this took place we cannot say; but judging from the considerable changes in geography which have undoubtedly taken place since then, we must conclude that many thousands of years, perhaps two hundred thousand, have intervened between this period and the present time.

When arctic conditions prevailed over this wide area, the plants and animals which now live in arctic latitudes flourished in Great Britain; but as the climate gradually became more genial, and the snow and ice melted, the plants and animals mostly retreated to their northern home. A certain number doubtless became extinct; but others took to the highest parts of the mountains, where snow and ice abound; and there they remain to the present day, separated from their fellows, but still enjoying the kind of climate to which they have always been accustomed, and testifying to the wonderful changes which have taken place since the mammoth, whose bones are found embedded in our river-gravels, wandered over the plains of Northern Europe.

Animal Life.

The rocky fastnesses of the Alps still afford a home to some of the larger wild animals which in other parts of Europe have gradually disappeared with the advance of civilisation. During the latter part of the "Stone Age," long before history was written, when men used axes, hammers, arrow-heads, and other implements of stone, instead of bronze or iron, Switzerland was inhabited by animals which are not to be seen now. The gigantic urus (Bos primigenius), which flourished in the forests of the interior during this prehistoric human period, and gave its name to the canton of Uri, has become extinct. The marsh hog was living during the period of the Swiss lake-dwellers. These people made their houses on piles driven in near the shore, and were acquainted with the use of bronze, and therefore later than the men of the "Stone Age." The remains of these strange dwelling-places have been discovered in several places, as well as many articles of daily use. The marsh hog has disappeared; and its place is taken by the wild boar and domestic hog, which afford sport and food to the present population. But taking Switzerland as it now is, we will say a few words about the more interesting forms of animal life dwelling in the Alps, beginning with those which are highest in the animal kingdom. Chief among these is the brown bear, still occasionally found, but it is exceedingly rare, except in the Grisons and in the districts of the Tyrol and Italy bordering on the canton, where it still carries on its ravages.[18] Some also believe that it still lingers in the rocky fastnesses of the Jura Mountains, to the east of the Alps. There is properly only one species of bear in Switzerland, but the hunters generally speak of three,—the great black, the great grey, and the small brown. The second of these is merely an accidental variety of the first; but between the grey and the small brown bears there is a good deal of difference. They assert that the black bear is not only considerably larger than the brown, but is also different in its habits. It is less ferocious and prefers a vegetable diet,—feeding on herbs, corn, and vegetables, with the roots and branches of trees. It has a way of plundering bee-hives and also ants' nests; it delights in strawberries and all kinds of fruit, plundering the orchards, and even making raids on the vineyards, but always retreating before dawn. As a rule it does not attack human beings. The brown bear is much more formidable, prowling by night about the sheepfolds, and causing the sheep by their fright to fall down precipices. Goats, when alarmed, leap on the roofs of the châlets, and bleat, in order to arouse the shepherds; so that when Bruin rears himself up against the wall he often meets his death. There are many stories on record of fierce fights for life between man and bear. The bear passes the winter in a torpid state, and eats little or nothing then.

The wolf, though still lingering in several lonely parts of the Alps, is rapidly becoming rare. It is most frequent in the districts about the Engadine and in the Jura Mountains. Only in winter-time, when hard pressed by hunger, does it approach the haunts of man. It takes almost any kind of prey it can get,—foxes, hares, rats, mice, birds, lizards, frogs, and toads. Sheep and goats are its favourite prey. The wolf is an affectionate parent, and takes his turn in looking after the nurslings, which is a necessary precaution, as his friends and relations have a way of eating up the babies.

The fox is common in many parts of the Alps, but not often seen by travellers. Instead of taking the trouble to burrow, he frequently manages by various cunning devices to take possession of a badger's hole. As Tschudi quaintly observes, "He has far too much imagination and poetic sentiment to like so monotonous and laborious an occupation as burrowing." Like the wolf, the mountain fox eats whatever he can catch, even beetles, flies, and bees. Those in the valleys live more luxuriously than their relations on the mountains,—plundering bee-hives and robbing orchards. As it was in Judæa in the days of Solomon, so it is now in Switzerland among the vineyards; and a peasant might well say, "Take us the foxes, the little foxes that spoil the vineyards."

The lynx is only occasionally found in the Alps, which is fortunate for the shepherds, for they can play terrible havoc with the sheep.

Wild-cats still linger in the most unfrequented parts. Their fur is valuable, and the flesh is sometimes eaten. The badger is far from common, though rarely seen by day. It is very cunning in avoiding traps, and so is generally either dug out of its hole drawn by dogs, or pulled out by a pole with nippers or a hook at the end. Passing on to less ferocious beasts, we find the otter common along the borders of rivers and lakes. The polecat, weasel, and stoat are often too abundant for keepers of poultry. The squirrel is common enough in the forests, but varies greatly in colour. It is doubtful whether the beaver still lingers by some lonely Alpine stream. It is last mentioned in a list of Swiss mammals, published in 1817, as found, though rarely, in some lonely spots. Rabbits are common, but hares rather scarce; of these there are, as in Scotland, two varieties,—the brown hare, which is seldom found at heights greater than four thousand to five thousand feet, and the blue hare, which ranges up to nine thousand feet. The latter changes colour: its fur in summer is of a dull bluish-grey, and in winter it becomes perfectly white, and so affords a striking illustration of "protective mimicry," for with snow lying on the ground it would be very hard to see the creature.

The marmot is common in all the higher Alpine regions. These interesting little creatures are very watchful, and easily scent danger. When an intruder approaches, a sentinel marmot utters a long shrill whistle, which is often repeated two or three times, and then they all make for their burrows; but it is not easy to distinguish them from the grey rocks among which they live. The fur is a yellowish or brownish grey, with black on the head and face, and a little white on the muzzle; the tail is short and bushy with a tipping of black. They have different quarters for summer and winter. The summer burrows are in the belt of rough pasture between the upper limits of trees and the snows; towards the end of autumn they come down to the pastures which the herdsmen have just abandoned and there make their winter burrows, which are much larger than the summer ones. Like rabbits, they frequently make a bolt-hole, by which they may escape from an intruder. In winter the holes are plugged up, and the marmots, rolling themselves up in a ball, go to sleep for six months or more. Sometimes hunters dig them out; but so soundly do they sleep that, according to De Saussure, they may often be taken out, placed in the game-bag, and carried home without being aroused. They wake up about April.

The chamois, a very favourite subject with the wood-carvers, is the only member of the antelope family in Western Europe; it is found in almost every part of the Alps, but is now much rarer than it was formerly. A full-grown chamois in good condition weighs about sixty pounds. The hair is thick, and changes colour with the season, being a red yellowish-brown in summer and almost black in winter. The horns, which curve backwards, rise from the head above and between the eyes to a height which rarely exceeds seven inches. When the kid is about three months old, the horns make their appearance, and at first are not nearly as hook-shaped as they afterwards become. When full-grown, it stands at the shoulder about two feet from the ground. The hind-legs being longer than the fore-legs, its gait is awkward on level ground, but they are admirably suited for mountain climbing. When at full speed, it can check itself almost instantly, and can spring with wonderful agility. Its hoofs are not well adapted for traversing the ice, and therefore it avoids glaciers as far as possible. Having a great fear of concealed crevasses, it is very shy of venturing on the upper part of a glacier; and the tracks which it leaves in these places often show by their windings and sudden turnings that the animal has exercised great caution. And so travellers often use this as a useful clue to getting safely over a glacier. Its agility is something extraordinary. It can spring across chasms six or seven yards wide, and "with a sudden bound leap up the face of a perpendicular rock, and merely touching it with its hoofs, rebound again in an opposite direction to some higher crag, and thus escape from a spot where, without wings, egress seemed impossible. When reaching upwards on its hind-legs, the fore-legs resting on some higher spot, it is able to stretch to a considerable distance, and with a quick spring bring up its hind-quarters to a level with the rest of the body, and with all four hoofs together, stand poised on a point of rock not broader than your hand."[19] The chamois feed on various mountain herbs, and on the buds and sprouts of the rhododendron and latschen (a pine). At night they couch among the broken rocks high upon the mountains, descending at daybreak to pasture, and retreating, as the heat increases, towards their fastnesses. When winter comes, they are forced down to the higher forests, where they pick up a scanty subsistence from moss, dead leaves, and the fibrous lichen which hangs in long yellowish-grey tufts from the fir-trees and bears the name of "chamois-beard." While browsing on this, they sometimes get their horns hooked in a bough, and so, being unable to disentangle themselves, perish with hunger. The senses of hearing, smell, and sight are exceedingly acute; so that the hunter must exercise all his craft to approach the animals. Pages might be filled with the hair-breadth escapes and fearful accidents which have befallen hunters; and yet they find the pursuit so fascinating that nothing will induce them to abandon it. A young peasant told the famous De Saussure (the pioneer of Alpine explorers) that though his father and grandfather before him had met their death while out on the hunt, not even the offer of a fortune would tempt him to change his vocation. The bag which he carried with him he called his winding-sheet, because he felt sure he would never have any other. Two years afterwards he was found dead at the foot of a precipice.

The bouquetin, or steinbock, once abundant throughout the greater part of the Alps, is now confined to certain parts where it is preserved by the King of Italy. De Saussure observes that in his time they had ceased to be found near Chamouni. Its whole build is remarkably strong, giving it quite a different appearance from the slender and graceful chamois.

The roe, the fallow deer, and the red deer have, it is said, quite disappeared from the French and Swiss Alps, but all of them occur in the Bavarian and Austrian highlands. They frequent the forests which clothe the lower slopes, and do not often wander into the more rocky districts. The wild boar only now and then appears across the Rhine, although it is common in the Subalpine forests farther east; but we can hardly consider it a true Alpine quadruped.

Passing on to the birds which frequent the Alps, we must first notice the bearded vulture, the lämmergeier of the Germans, which once was common, but now only holds its own here and there in some lonely mountain fastness. Although preferring living prey to carrion, still in many ways it is closely allied to the true vulture. The upper part of the body is a greyish-brown hue, the under side white, tinged with reddish brown. The nest, built on a high ledge of rock, consists of straw and fern, resting on sticks, on which are placed branches lined with moss and down. It is a rare thing for the traveller to obtain a view of this monarch of the Alpine birds. Like the true vulture, its digestive powers are marvellous. According to Tschudi ("Les Alpes"), the stomach of one of these birds was found to contain five fragments of a cow's rib, a mass of matted wool and hair, and the leg of a kid perfect from the knee downwards. Another had bolted a fox's rib fifteen inches long, as well as the brush, besides a number of bones and other indigestible parts of smaller animals, which were slowly being eaten away by the gastric juice. Sheep, goats, full-grown chamois, and smaller quadrupeds are eagerly devoured by this voracious bird. It is said to be bold enough to attack a man, when it finds him asleep or climbing in any dangerous place. Tschudi, in his book on the Alps, gives several instances of young children being carried off. One of these happened in the Bernese Oberland, as follows: Two peasants, making hay upon the pastures, had taken with them their daughter Anna, a child about three years old. She quickly fell asleep on the turf near the hay châlet; so the father put his broad-brimmed hat over her face, and went to work some little way off. On his return with a load of hay the child was gone; and a brief search showed that she was nowhere near. Just at this time a peasant walking along a rough path in the glen was startled by the cry of a child, and going towards the place whence it came, saw a lämmergeier rise from a neighbouring summit and hover for some time over a precipice. On climbing thither in all haste, he found the child lying on the very brink. She was but little injured; some scratches were found on her hands and on the left arm, by which she had been seized; and she had been carried more than three quarters of a mile through the air. She lived to a good old age, and was always called the Geier-Anna, or Vulture's Annie, in memory of her escape. The particulars are inscribed in the registers of the parish of Habkeren.

The golden eagle is not uncommon in most parts of the Alps, although travellers rarely obtain a near view. It is said to be very fond of hares, chasing and capturing them very cleverly. As in Great Britain, it is accused of carrying off children; but this is at least doubtful. The kite, buzzard and falcon are occasionally seen. There are at least ten species of owls, among which is the magnificent eagle-owl. The raven is found in the lonelier glens, and is often tamed. Its thieving propensities are very amusing. Alpine birds of prey correspond very closely with British. The jackdaw is also common. It would be impossible within our short limits to give a complete list of Swiss birds, but we may mention among others the nutcracker, the jay, the white-breasted swift, the wheatear, the common black redstart, the beautiful wall-creeper, and the snow-finch, which mounts to the borders of the snow. Of game-birds we may mention the capercailze, the black grouse, and the hazel grouse, all of which are common in many of the forests. The ptarmigan haunts the stony tracts on the borders of perpetual snow. In winter it turns white, and in summer greyish-brown, though a good deal of white remains.

Pheasants and partridges cannot be said to be Alpine birds; but the Greek partridge may be so considered.

Numbers of the mountain streams and tarns contain excellent trout, and most of the larger lakes are well stocked with fish. Some of the trout of the Swiss and Italian lakes are of great size. The pike frequently weigh twelve to fifteen pounds.

Reptiles are not numerous. The common frog, which is said to be found as high as ten thousand feet above the sea, swarms in some parts of the Rhone Valley. Of true lizards, five species have been recognized. The blind-worm (which is not a snake), so common on many of our English heaths, is often met with. Among the true snakes we find the English ringed snake—quite harmless—and two adders. The common adder is found at a height of seven thousand feet above the sea.

Lower forms of life not possessing a backbone (invertebrates) abound in this region; but they are far too numerous to be considered here. Butterflies and moths are abundant; and many of those which are rare in England are common in the Alps, so that the entomologist finds a happy hunting-ground. The beautiful swallowtail and the handsome apollo, coppers, painted ladies, fritillaries, and many other Lepidoptera thrive in these regions, and are less easily frightened than at home in England.

Probably every mountain climber, resting for a brief space on a loose boulder, or seeking the shade of some overhanging piece of rock, has often asked himself, "How were all these rocks made?" The question must occur again and again to any intelligent person on visiting a mountain for the first time, or even on seeing a mountain-range in the distance. He may well ask his companions how these great ramparts of the earth were built up. But unless he possesses some knowledge of the science of geology, which tells of the manifold changes which in former ages have taken place on the earth, or unless, in the absence of such knowledge, he chance to meet with a geologist, his question probably remains unanswered. Such questions, however, can be very satisfactorily answered,—thanks to the labours of zealous seekers after truth, who have given the best part of their lives to studying the rocks which are found everywhere on the surface of the earth, and the changes they undergo. Geology is a truly English science; and Englishmen may well cherish gratefully the memories of its pioneers,—Hutton, Playfair, Lyell, and others, who have made the way so clear for future explorers.

The story of the hills as written on their own rocky tablets and on the very boulders lying loose on their sloping sides, and interpreted by geologists, is a long one; for it takes us far back into the dim ages of the past, and like the fashionable novel, may be divided into three parts, or volumes. To those who follow the stony science it is quite as fascinating as a modern romance, and a great deal more wonderful, thus illustrating the force of the old saying, "Truth is stranger than fiction."

The three parts of our story may be best expressed by the three following inquiries:

1. I.   How were the materials of which mountains are built up brought together and made into hard rock?
2. II.  How were they raised up into the elevated positions in which we now find them?
3. III. How were they carved out into all their wonderful and beautiful features of crag and precipice, peaks and passes?

A mountain group, with its central peak or spire, its long ridges, steep walls, towers, buttresses, dark hollows, and carved pinnacles standing out against the sky, has well been compared to a great and stately building such as a cathedral or a temple. Mountains are indeed "a great and noble architecture, giving first shelter, comfort, and rest, but covered also with mighty sculpture and painted legend;" and to many they are Nature's shrines, where men may offer their humble praises and prayers to the great Architect who reared them for His children. We have introduced this illustration because it will help us in our inquiry. Suppose we were standing in front of some great cathedral, such as Milan, with all its marble pinnacles, or Notre Dame, with its stately towers, or the minsters of York or Durham in our own country, and trying to picture to ourselves how it was built. No one has lived long enough to watch the completion of one of these great buildings; but for all that, we know pretty well how it was made, even by watching the builder's operations for a short time, or by following, as we often may, the various stages in the construction of a small house. So it is with Nature's work. We cannot, in our little lives, witness the rearing of a great mountain-chain, or even the carving of a single hill; but we can observe for ourselves the slow and continuous operations which in the course of thousands and thousands of years produce such stupendous results. We may learn how the building operations are conducted, though the final results will only be manifested in the far-distant future.

But to return to our cathedral. If we try to picture to ourselves the long years during which it was covered with scaffolding and surrounded by a busy army of workers, we shall soon perceive that the operations may be broadly divided into three heads. First, we must inquire how the separate stones of which it is composed were brought together into one place, and we shall at once picture to ourselves groups of men working in stone-quarries,—perhaps a long way off,—busy with their crowbars and hammers, breaking off large blocks of stone, and following the natural divisions of the rock that their rough labour may be lessened; for all rocks will split more easily along certain lines than along others. Sometimes it is easier to follow the "bedding," or natural layers in which the rock was formed; at other times the "joints," or cracks subsequently formed as the rocky materials hardened and contracted in bulk, afford easier lines for the workmen to follow. Others are busily engaged in placing the stony blocks on trollies drawn by horses, that they may be borne along the roads leading from the quarry to the site of the future cathedral. And so, taking a bird's-eye view, we seem to see horses and carts slowly moving on from many a distant quarry, but all converging like the branches of a river to one main channel, and finally depositing their burdens in the stone-yard where the masons are at work. Perhaps bricks are partly employed, in which case we can easily picture to ourselves the brickyards, where some are digging out the soft clay, others moulding it into bricks with wooden moulds, while others again lay them down in rows on the ground to dry, before they are baked in the ovens. And when the bricks are ready for use, the same means of transportation are employed; and cart-loads of them are borne along the country roads until they so reach their destination.

Now, all this may be summed up in the one word "transportation;" and we shall presently inquire how the rocky matter of which the mountains are built was transported.

Secondly. We have to inquire how the bricks and stones were raised up. The analogy is not quite perfect in this case; for the mountains were raised up en bloc, not bit by bit and stone by stone, as in the case of the cathedral. Still they have been raised somehow. Analogies are seldom complete in every detail; but for all that, our illustration serves well enough, and will help us in following the various processes of mountain building. In these days, the raising of the stones is mostly effected by steam-power applied to big cranes and pulleys. In old days they used cranes and pulleys, but the ropes were pulled by hand-power. In either case the work proceeds slowly; and we can easily picture to ourselves the daily raising of the stones of which the cathedral is composed. "What were the forces at work which slowly raised the mountains?" This question we will endeavour to answer later on (see next chapter). This work may be included in the one word, "elevation."

And lastly. We must inquire how the carving of the stately building was effected, how its pinnacles received their shape, and how all those lovely details received their final forms; how the intricate traceries of its windows were made, and the statues carved which adorn its solemn portals. This question is easily answered, for we are all more or less familiar with what goes on in a stone-mason's yard. Under those wooden sheds we see a number of skilled labourers at work, busy with their chisels and mallets, cutting out, according to the patterns made from the architect's detailed drawings, the portions of tracery for windows, or the finials, crockets, and other features of the future building. In another part of the yard may be seen the stone-cutters, working in pairs and slowly pulling backwards and forwards those long saws which, with the help of water and sand, in time cut through the biggest blocks. All this work then may be summed up under the one word, "ornamentation," for it includes the cutting and carving of the stone.

Our three lines of inquiry may now be summed up in these three words, which are easily remembered:—

Taking the first of these subjects for consideration in the present chapter, we have now to inquire into the nature of the materials of which mountains are composed and the means by which they have been brought together and compacted into hard rock.

First, with regard to the nature of the materials which Mother Earth uses to build her rocky ramparts: they are the same as the ordinary rocks of which the earth's crust is composed; and the greater part of them have been formed by the action of water. These are the ordinary "stratified" rocks, which in one form or another meet us almost everywhere, and may be said to be aqueous deposits, or sediments formed in seas and inland lakes. They are always arranged in layers, known to geologists as "strata," because they have been gently laid down, or strewn (Latin, stratum), at the bottom of some large body of water. There were pauses in the deposition of the materials, during which each layer had time to harden a little before the next one was formed. This accounts for the stratification. In this way great deposits of sandstone, clay, and limestone, with their numerous varieties, have been in the course of ages gradually piled up, till they have attained to enormous thickness, which at first sight seem almost incredible; but the bed of the seas in which they formed was probably undergoing a slow sinking process that kept pace with the growth of these deposits, otherwise the sea might have been more or less filled up.

And these processes are still going on. In fact, it is entirely by watching what goes on now that geologists are able to explain what took place a very long time ago when there were no human beings on the earth to record the events that took place. And so we argue from the present to the past, from the known to the unknown. In other words, geology is based upon physical geography, which tells us of the changes now in progress on the earth. Thus, sandstone, as frequently met with in different parts of Great Britain, and largely used for building purposes, such as the familiar old red sandstone[20] of South Wales, Hereford, and the north of England and different parts of Scotland, was once soft sand in no way at all different from the sand of the seashore at the present day, or of the sandy bed of the North Sea. In process of time it became hardened, and acquired its characteristic red colour, which is due to oxide of iron. In some places numerous fossil fishes have been discovered in this interesting formation, so intimately associated with the name of Hugh Miller, who first thoroughly explored it; these and other remains entombed therein tell us of the strange forms of life which flourished on the earth during that very old-fashioned period of the world's history; and by putting together all kinds of evidences derived from the rock itself, geologists are able to form a very good idea of the way in which this rock-deposit was accumulated, always, however, basing their conclusions on a thorough knowledge of what goes on at the present day in seas, rivers, and inland lakes.

In the great series of stratified rocks forming what is commonly called the crust of the earth (an unfortunate term which has survived from the time when the interior of the earth was generally believed to be in a fiery molten condition, and covered by a thin coating of solid rock at the surface), there are besides the sandstones, of which we have just spoken, great deposits of dark-coloured clays, shales, and slates. All these can be accounted for by the geologist. They are simply different states of what was once soft mud. The slates tell us that they have been subjected to very severe pressure, which squeezed their particles till they were elongated and all arranged in one direction, and this is the reason why they split up into thin sheets.

Others, again, represent vast deposits of carbonate of lime, thousands of feet thick and now occupying hundreds of square miles of the earth's surface. Limestone rocks are as abundant in our own country as the sandstones, shales, or slates. The chalk of which the North and South Downs are composed is a familiar example. It is seen again forming Salisbury Plain, in Hampshire and the Isle of Wight, and then it may be traced running up the country in a long band through the counties of Oxford, Cambridge, Lincoln, until it reaches the coast at Flamborough Head in Yorkshire. Then we have the Bath Oölites so much used in building, for they form an admirable "freestone" that can be easily carved and cut in any direction (hence the term "freestone"); and lastly, the great mountain limestone so well developed in South Wales, Yorkshire, and the Lake country. All these were slowly built up at the bottom of the seas which existed in past ages; great beds of gravel formed at the mouths of rivers, and long banks of pebbles and rounded stones collected on the shore of primeval seas, and were ground against each other as now by the action of the waves, until all their corners were rubbed off. Pebble-beds, called by geologists conglomerates, are met with among the stratified rocks; and their story is easily read by studying what takes place at the present day on our seashores.

Now, the sandstones, clays, gravels, and pebble-beds all represent, as will presently be explained, so much material worn away from the surface of the land and swept into the ocean (or in some cases into inland seas and lakes) by streams and rivers, which are the great transporting agents of the world. Hence such deposits of débris, supplied by the constant wear and tear of all rocks exposed to the atmosphere, are truly sedimentary and have a purely mechanical origin. But it is not so with the limestones. The latter were never transported, but grew at the bottom of the sea in very wonderful ways. They have nothing to do with the wear and tear of the land to which the others owe their existence, but represent vast quantities of carbonate of lime extracted from sea water. Sea water contains a certain amount of this substance in a dissolved state, or "in solution," as a chemist would say; and the way in which this is extracted by the agency of various creatures, such as coral polypes and little microscopic creatures that build their shells of carbonate of lime, of great beauty, forms one of the most interesting subjects presented to the student of physical geography. Hence, since limestone can only be accounted for by the agency of living organisms,[21] it is rightly termed an organic deposit, and the others are said to be mechanical deposits. But both are called "aqueous rocks," because they are formed under water. It is important to distinguish clearly between these two very different methods of rock-formation.

But although water plays such a very important part in the making of the common rocks around us, yet there are others which have quite a different origin,—rocks which have come up from below the surface of the earth in a heated and molten condition, such as the lavas that flow from volcanoes in active eruptions and the showers of ashes and fine volcanic dust which often attend such eruptions (see chap. viii., pp. 271-272). Some highly heated rocks, though they never rise to the surface to form lava-flows, are forced up with overwhelming pressure from below, and wedge themselves into the sedimentary rocks that overlie them, thus forming what are known as volcanic dykes, and intrusive masses or sheets of once molten rock. In this category we include such rocks as basalt, felstone, pitchstone, and other rocks of fiery origin that have flowed from volcanoes as lava, as well as those like granite, which have cooled and become solid below the surface, and are Plutonic, or deep-seated, igneous rocks. Granite may be exposed to the surface of the earth when the rocks which once overlaid it have been worn away or "denuded." It is frequently seen in the central regions of mountain-chains, where a vast amount of erosion has been effected. Thus we see that heat has played its part in the making of rocks; and for this reason such rocks as we have just mentioned are called igneous. Fire and water are therefore very important geological agents; but we should say heat rather than fire, because the latter word might convey a false impression. No rocks can be burned except coal, which may be considered rather as a mineral deposit than as a rock. Some rocks may be heated, and undergo many and various changes in their mineral composition; but they are not capable of combustion.

So far, then, we have learned that the rocks exposed to view on the surface of the earth may be divided into two classes; that is, aqueous and igneous. There is yet a third class, which, though of aqueous origin, has in course of time suffered considerable from the internal heat of the earth and the enormous pressure due to the weight of overlying rocks. Such rocks have been greatly changed from their original condition, both in appearance and in mineral composition, and are said to be "metamorphic," a word which implies change. Thus chalk, or other limestone rock, has been metamorphosed into marble; shales and slates into various kinds of "schists,"[22] such as mica-schist, and even into gneiss, which closely resembles granite. And it is quite possible that even granite may in some cases be the result of the melting and consolidation under great pressure of certain familiar stratified rocks. It is quite conceivable that slate might be converted into granite, for their chemical composition is similar, only the minerals of which it is composed would require to be rearranged and grouped into new compounds. This would seem quite possible; but at present we have no direct proof of such a change having taken place. Even igneous rocks are found in some places to have suffered very considerable change.

In some inland seas, like the Caspian Sea, deposits of rock salt and gypsum may be formed by chemical precipitation, owing to evaporation from the surface.

The various kinds of rock known to geologists may be conveniently arranged as follows:

So far we have only attempted to state very briefly the different kinds of rocks, and to point out that they were formed in various ways. We must now consider the question of rock-making more closely, and see what we can learn about the wonderful ways in which rocks are made; and it may be instructive to glance at the conflicting opinions on this subject which learned men held not very long ago.

At the end of the last century a great controversy took place on the question of the origin of rocks, and the learned men of the day were divided into two parties. One of these parties, following the teaching of Werner, professor of mining at Freyburg, who inspired great enthusiasm among his disciples, declared that all rocks were formed by the agency of water. This was a very sweeping and of course rash conclusion. But whenever they examined rocks, they found so many clear evidences of the action of water that a powerful impression of the importance of this agency was naturally made on their minds. They found rocks uniformly arranged in great layers which extended for long distances, and containing the remains of animals which must undoubtedly have lived in the seas or estuaries. These layers were further divided into smaller layers, such as clearly were formed by the slow settling down of sand and mud. Others again contained gravels and rounded pebbles, testifying in no uncertain way to the action of water. Even the little grains of sand are obviously water-worn. This teaching was quite sound so long as they confined their attention to clays, sandstones, and limestones; but when they came to basalt and granite, a blind adherence to the views of their master caused them to shut their eyes to the clear evidences of the action of heat, presented by such rocks. The crystalline structure of such rocks; their irregular arrangement, often so different from the uniform disposition of the stratified rocks (although it must be admitted that ancient lava-flows often lie very evenly between aqueous rocks), and the way in which they burst through overlying rocks, thus proving their former molten condition; the signs of alteration exhibited in the aqueous rocks into which they intruded themselves (changes which are obviously due to the action of heat),—these and other evidences were entirely overlooked, and Werner declared that basalt had been found as a sediment under water.

This school of geologists, believing so strongly in the all-powerful influence of Father Neptune, received the not inappropriate title of "Neptunists."

On the other hand, the party who happened to be in districts where granite, basalt, and such igneous rocks abounded were equally impressed with the importance of the powerful agency of heat. To them nearly every rock they met with seemed to show some signs of its action. And since Pluto was the classical deity of the lower regions, and the earth shows evidences in places of greater heat below the surface, this party received the title of "Plutonists;" and so the battle raged hotly for some time between the Neptunists, with their claims for cold water, and the fiery Plutonists of the rival school of Edinburgh, with their subterranean heat. Fire and water are never likely to agree; and they did not do so in this case. But now that the battle is over, and both sides are found to have been partly right and partly wrong,—though the Neptunists have the advantage,—we can afford to smile at the fierceness of the contest, and wonder how it was that each side thought they were so entirely in the right.

Let us now consider the aqueous rocks, and see if we can gain a clear idea of the ways in which they were formed; and first, we will take those of a purely sedimentary origin,—the sandstones, pebble-beds, gravels, and clays. These, as the reader has already probably guessed, have all been transported by means of streams and rivers, and settled down quietly in seas at the mouths of rivers or in inland lakes. There is no trace of the action of heat in the forming of these rocks, though they often show signs of having suffered more or less change from contact with highly heated igneous rocks of later date which forcibly intruded themselves from below; and if the change thus effected were considerable, we should call the rocks so altered metamorphic. But we are now dealing with their original state and how they were made; and of that there is no possible doubt whatever. So for the time being we may call ourselves Neptunists.

Streams and rivers are the great transporting agents whereby the never-failing supply of débris from the waste of the land is unceasingly brought down from the mountains and hills, through the broad valleys and along the great plains, until finally it is flung into the sea. The sea is the workshop where all the sedimentary rocks are slowly manufactured from the raw material brought to it by the rivers. But for the present we must confine our attention to the question of transport. Referring back to our illustration of the cathedral, we may say that streams and rivers play the part of cart and horses. They bring the materials down from the quarry to the scene of action,—the workshop where they are wanted. The quarries, in this case, may be said to be almost everywhere. For wherever rocks and soil are exposed to the action of wind and weather, there is certain to be more or less decay and crumbling away. But it is among the hills and in the higher parts of the mountains that the forces of destruction are most active. How this is brought about will be discussed in the seventh chapter, on the carving of the hills. The frequent slopes covered with loose stones are sufficient evidence of the continual destruction that takes place in these regions.

The transporting powers of rivers are truly prodigious. Looking at a stream or river after heavy rain, we see its waters heavily laden with mud and sand; but it is difficult to realise from a casual glance the vast amount of material that is thus brought down to lower levels. If we could trace the sediment to its source, we must seek it among the rocks of mountains far away. Step by step we may trace it up along the higher courses of the river, then along mountain streams rushing over their rocky beds, tumbling in cascades over broken rocks, or leaping in waterfalls over higher projections of rock, until we come to the deep furrows on the sides of mountains along which loose fragments of rock come tumbling down with the cascades of water that run along these steep channels after heavy rain, leaving at the base of the mountain great fan-shaped heaps of stones.