On the Downs indeed things change slowly, and in parts of Sussex the strong slow oxen still draw the waggons laden with warm hay or golden wheat sheaves, or drag the wooden plough along the slopes of the Downs, just as they did a thousand years ago.

I love the open Down most, but without hedges England would not be England. Hedges are everywhere full of beauty and interest, and nowhere more so than at the foot of the Downs, when they are in great part composed of wild Guelder Roses and rich dark Yews, decked with festoons of Traveller's Joy, the wild Bryonies, and garlands of Wild Roses covered with thousands of white or delicate pink flowers, each with a centre of gold.

At the foot of the Downs spring clear sparkling streams; rain from heaven purified still further by being filtered through a thousand feet of chalk; fringed with purple Loosestrife and Willowherb, starred with white Water Ranunculuses, or rich Watercress, while every now and then a brown water rat rustles in the grasses at the edge, and splashes into the water, or a pink speckled trout glides out of sight.

In many of our midland and northern counties most of the meadows lie in parallel undulations or "rigs." These are generally about a furlong (220 yards) in length, and either one or two poles (5-1/2 or 11 yards) in breadth. They seldom run straight, but tend to curve towards the left. At each end of the field a high bank, locally called a balk, often 3 or 4 feet high, runs at right angles to the rigs. In small fields there are generally eight, but sometimes ten, of these rigs, which make in the one case 4, in the other 5 acres. These curious characters carry us back to the old tenures, and archaic cultivation of land, and to a period when the fields were not in pasture, but were arable.

They also explain our curious system of land measurement. The "acre" is the amount which a team of oxen were supposed to plough in a day. It corresponds to the German "morgen" and the French "journee." The furlong or long "furrow" is the distance which a team of oxen can plough conveniently without stopping to rest. Oxen, as we know, were driven not with a whip, but with a goad or pole, the most convenient length for which was 16-1/2 feet, and the ancient ploughman used his "pole" or "perch" by placing it at right angles to his first furrow, thus measuring the amount he had to plough. Hence our "pole" or "perch" of 16-1/2 feet, which at first sight seems a very singular unit to have selected. This width is also convenient both for turning the plough, and also for sowing. Hence the most convenient unit of land for arable purposes was a furlong in length and a perch or pole in width.

The team generally consisted of eight oxen. Few peasants, however, possessed a whole team, several generally joining together, and dividing the produce. Hence the number of "rigs," one for each ox. We often, however, find ten instead of eight; one being for the parson's tithe, the other tenth going to the ploughman.

When eight oxen were employed the goad would not of course reach the leaders, which were guided by a man who walked on the near side. On arriving at the end of each furrow he turned them round, and as it was easier to pull than to push them, this gradually gave the furrow a turn towards the left, thus accounting for the slight curvature. Lastly, while the oxen rested on arriving at the end of the furrow, the ploughmen scraped off the earth which had accumulated on the coulter and ploughshare, and the accumulation of these scrapings gradually formed the balk.

It is fascinating thus to trace indications of old customs and modes of life, but it would carry us away from the present subject.

Even though the Swiss meadows may offer a greater variety, our English fields are yet rich in flowers: yellow with Cowslips and Primroses, pink with Cuckoo flowers and purple with Orchis, while, however, unwelcome to the eye of the farmer,

the rich Buttercup Its tiny polished urn holds up, Filled with ripe summer to the edge,[36]

turning many a meadow into a veritable field of the cloth of gold, and there are few prettier sights in nature than an English hay field on a summer evening, with a copse perhaps at one side and a brook on the other; men with forks tossing the hay in the air to dry; women with wooden rakes arranging it in swathes ready for the great four-horse waggon, or collecting it in cocks for the night; while some way off the mowers are still at work, and we hear from time to time the pleasant sound of the whetting of the scythe. All are working with a will lest rain should come and their labour be thrown away. This too often happens. But though we often complain of our English climate, it is yet, take it all in all, one of the best in the world, being comparatively free from extremes either of heat or cold, drought or deluge. To the happy mixture of sunshine and of rain we owe the greenness of our fields,

sparkling with dewdrops Indwelt with little angels of the Sun,[37]

lit and

warmed by golden sunshine And fed by silver rain,

which now and again sprinkles the whole earth with diamonds.

FOOTNOTES:

[22] The Spectator.

[23] Milton.

[24] Jefferies.

[25] Forbes, A Naturalist's Wanderings in the Eastern Archipelago.

[26] Tennyson.

[27] Hamerton.

[28] Marvell.

[29] Ruskin.

[30] Thomson, Voyage of the Challenger.

[31] Thomson, Voyage of the Challenger.

[32] Sir J. Paget, On the Pathology of Plants.

[33] Evelyn's Sylva.

[34] Modern Painters.

[35] M. Correvon informs me that the Gruyere cheese is supposed to owe its peculiar flavour to the alpine Alchemilla, which is now on that account often purposely sown elsewhere.

[36] J. R. Lowell.

[37] Hamerton.



CHAPTER VI

MOUNTAINS

Mountains "seem to have been built for the human race, as at once their schools and cathedrals; full of treasures of illuminated manuscript for the scholar, kindly in simple lessons for the worker, quiet in pale cloisters for the thinker, glorious in holiness for the worshipper. They are great cathedrals of the earth, with their gates of rock, pavements of cloud, choirs of stream and stone, altars of snow, and vaults of purple traversed by the continual stars."—RUSKIN.



CHAPTER VI

MOUNTAINS

The Alps are to many of us an inexhaustible source of joy and peace, of health, and even of life. We have gone to them jaded and worn, feeling, perhaps without any external cause, anxious and out of spirits, and have returned full of health, strength, and energy. Among the mountains Nature herself seems freer and happier, brighter and purer, than elsewhere. The rush of the rivers, and the repose of the lakes, the pure snowfields and majestic glaciers, the fresh air, the mysterious summits of the mountains, the blue haze of the distance, the morning tints and the evening glow, the beauty of the sky and the grandeur of the storm, have all refreshed and delighted us time after time, and their memories can never fade away.

Even now as I write comes back to me the bright vision of an Alpine valley—blue sky above, glittering snow, bare grey or rich red rock, dark pines here and there, mixed with bright green larches, then patches of smooth alp, with clumps of birch and beech, and dotted with brown chalets; then below them rock again, and wood, but this time with more deciduous trees; and then the valley itself, with emerald meadows, interspersed with alder copses, threaded together by a silver stream; and I almost fancy I can hear the tinkling of distant cowbells coming down from the alp, and the delicious murmur of the rushing water. The endless variety, the sense of repose and yet of power, the dignity of age, the energy of youth, the play of colour, the beauty of form, the mystery of their origin, all combine to invest mountains with a solemn beauty.

I feel with Ruskin that "mountains are the beginning and the end of all natural scenery; in them, and in the forms of inferior landscape that lead to them, my affections are wholly bound up; and though I can look with happy admiration at the lowland flowers, and woods, and open skies, the happiness is tranquil and cold, like that of examining detached flowers in a conservatory, or reading a pleasant book." And of all mountain views which he has seen, the finest he considers is that from the Montanvert: "I have climbed much and wandered much in the heart of the high Alps, but I have never yet seen anything which equalled the view from the cabin of the Montanvert."

It is no mere fancy that among mountains the flowers are peculiarly large and brilliant in colour. Not only are there many beautiful species which are peculiar to mountains,—alpine Gentians, yellow, blue, and purple; alpine Rhododendrons, alpine Primroses and Cowslips, alpine Lychnis, Columbine, Monkshood, Anemones, Narcissus, Campanulas, Soldanellas, and a thousand others less familiar to us,—but it is well established that even within the limits of the same species those living up in the mountains have larger and brighter flowers than their sisters elsewhere.

Various alpine species belonging to quite distinct families form close moss-like cushions, gemmed with star-like flowers, or covered completely with a carpet of blossom. On the lower mountain slopes and in alpine valleys trees seem to flourish with peculiar luxuriance. Pines and Firs and Larches above; then, as we descend, Beeches and magnificent Chestnuts, which seem to rejoice in the sweet, fresh air and the pure mountain streams.

To any one accustomed to the rich bird life of English woods and hedgerows, it must be admitted that Swiss woods and Alps seem rather lonely and deserted. Still the Hawk, or even Eagle, soaring high up in the air, the weird cry of the Marmot, and the knowledge that, even if one cannot see Chamois, they may all the time be looking down on us, give the Alps, from this point of view also, a special interest of their own.

Another great charm of mountain districts is the richness of colour. "Consider,[38] first, the difference produced in the whole tone of landscape colour by the introductions of purple, violet, and deep ultra-marine blue which we owe to mountains. In an ordinary lowland landscape we have the blue of the sky; the green of the grass, which I will suppose (and this is an unnecessary concession to the lowlands) entirely fresh and bright; the green of trees; and certain elements of purple, far more rich and beautiful than we generally should think, in their bark and shadows (bare hedges and thickets, or tops of trees, in subdued afternoon sunshine, are nearly perfect purple and of an exquisite tone), as well as in ploughed fields, and dark ground in general. But among mountains, in addition to all this, large unbroken spaces of pure violet and purple are introduced in their distances; and even near, by films of cloud passing over the darkness of ravines or forests, blues are produced of the most subtle tenderness; these azures and purples passing into rose colour of otherwise wholly unattainable delicacy among the upper summits, the blue of the sky being at the same time purer and deeper than in the plains. Nay, in some sense, a person who has never seen the rose colour of the rays of dawn crossing a blue mountain twelve or fifteen miles away can hardly be said to know what tenderness in colour means at all; bright tenderness he may, indeed, see in the sky or in a flower, but this grave tenderness of the far-away hill-purples he cannot conceive."

"I do not know," he says elsewhere, "any district possessing a more pure or uninterrupted fulness of mountain character (and that of the highest order), or which appears to have been less disturbed by foreign agencies, than that which borders the course of the Trient between Valorsine and Martigny. The paths which lead to it, out of the valley of the Rhone, rising at first in steep circles among the walnut trees, like winding stairs among the pillars of a Gothic tower, retire over the shoulders of the hills into a valley almost unknown, but thickly inhabited by an industrious and patient population. Along the ridges of the rocks, smoothed by old glaciers, into long, dark, billowy swellings, like the backs of plunging dolphins, the peasant watches the slow colouring of the tufts of moss and roots of herb, which, little by little, gather a feeble soil over the iron substance; then, supporting the narrow strip of clinging ground with a few stones, he subdues it to the spade, and in a year or two a little crest of corn is seen waving upon the rocky casque."

Tyndall, speaking of the scene from the summit of the Little Scheideck,[39] says: "The upper air exhibited a commotion which we did not experience; clouds were wildly driven against the flanks of the Eiger, the Jungfrau thundered behind, while in front of us a magnificent rainbow, fixing one of its arms in the valley of Grindelwald, and, throwing the other right over the crown of the Wetterhorn, clasped the mountain in its embrace. Through jagged apertures in the clouds floods of golden light were poured down the sides of the mountain. On the slopes were innumerable chalets, glistening in the sunbeams, herds browsing peacefully and shaking their mellow bells; while the blackness of the pine trees, crowded into woods, or scattered in pleasant clusters over alp and valley, contrasted forcibly with the lively green of the fields."

Few men had more experience of mountains than Mr. Whymper, and from him, I will quote one remarkable passage describing the view from the summit of the Matterhorn just before the terrible catastrophe which overshadows the memory of his first ascent.

"The day was one of those superlatively calm and clear ones which usually precede bad weather. The atmosphere was perfectly still and free from all clouds or vapours. Mountains fifty, nay, a hundred miles off looked sharp and near. All their details—ridge and crag, snow and glacier—stood out with faultless definition. Pleasant thoughts of happy days in bygone years came up unbidden as we recognised the old familiar forms. All were revealed, not one of the principal peaks of the Alps was hidden. I see them clearly now, the great inner circle of giants, backed by the ranges, chains, and massifs.... Ten thousand feet beneath us were the green fields of Zermatt, dotted with chalets, from which blue smoke rose lazily. Eight thousand feet below, on the other side, were the pastures of Breuil. There were black and gloomy forests; bright and cheerful meadows, bounding waterfalls and tranquil lakes, fertile lands and savage wastes, sunny plains and frigid plateaux. There were the most rugged forms and the most graceful outlines, bold perpendicular cliffs and gentle undulating slopes; rocky mountains and snowy mountains, sombre and solemn, or glittering and white, with walls, turrets, pinnacles, pyramids, domes, cones, and spires! There was every combination that the world can give, and every contrast that the heart could desire."

These were summer scenes, but the Autumn and Winter again have a grandeur and beauty of their own.

"Autumn is dark on the mountains; grey mist rests on the hills. The whirlwind is heard on the heath. Dark rolls the river through the narrow plain. The leaves twirl round with the wind, and strew the grave of the dead."[40]

Even bad weather often but enhances the beauty and grandeur of mountains. When the lower parts are hidden, and the peaks stand out above the clouds, they look much loftier than if the whole mountain side is visible. The gloom lends a weirdness and mystery to the scene, while the flying clouds give it additional variety.

Rain, moreover, adds vividness to the colouring. The leaves and grass become a brighter green, "every sunburnt rock glows into an agate," and when fine weather returns the new snow gives intense brilliance, and invests the woods especially with the beauty of Fairyland. How often in alpine districts does one long "for the wings of a dove," more thoroughly to enjoy and more completely to explore, the mysteries and recesses of the mountains. The mind, however, can go, even if the body must remain behind.

Each hour of the day has a beauty of its own. The mornings and evenings again glow with different and even richer tints.

In mountain districts the cloud effects are brighter and more varied than in flatter regions. The morning and evening tints are seen to the greatest advantage, and clouds floating high in the heavens sometimes glitter with the most exquisite iridescent hues

that blush and glow Like angels' wings.[41]

On low ground one may be in the clouds, but not above them. But as we look down from mountains and see the clouds floating far below us, we almost seem as if we were looking down on earth from one of the heavenly bodies.

Not even in the Alps is there anything more beautiful than the "after glow" which lights up the snow and ice with a rosy tint for some time after the sun has set. Long after the lower slopes are already in the shade, the summit of Mont Blanc for instance is transfigured by the light of the setting sun glowing on the snow. It seems almost like a light from another world, and vanishes as suddenly and mysteriously as it came.

As we look up from the valleys the mountain peaks seem like separate pinnacles projecting far above the general level. This, however, is a very erroneous impression, and when we examine the view from the top of any of the higher mountains, or even from one of very moderate elevation, if well placed, such say as the well-known Piz Languard, we see that in many cases they must have once formed a dome, or even a table land, out of which the valleys have been carved. Many mountain chains were originally at least twice as high as they are now, and the highest peaks are those which have suffered least from the wear and tear of time.

We used to speak of the everlasting hills, and are only beginning to realise the vast and many changes which our earth has undergone.

There rolls the deep where grew the tree. O earth, what changes hast thou seen! There where the long street roars, hath been The stillness of the central sea.

The hills are shadows, and they flow From form to form, and nothing stands; They melt like mist, the solid lands, Like clouds they shape themselves and go.[42]

THE ORIGIN OF MOUNTAINS

Geography moreover acquires a new interest when we once realise that mountains are no mere accidents, but that for every mountain chain, for every peak and valley, there is a cause and an explanation.

The origin of Mountains is a question of much interest. The building up of Volcanoes is even now going on before our eyes. Some others, the Dolomites for instance, have been regarded by Richthofen and other geologists as ancient coral islands. The long lines of escarpment which often stretch for miles across country, are now ascertained, mainly through the researches of Whitaker, to be due to the differential action of aerial causes. The general origin of mountain chains, however, was at first naturally enough attributed to direct upward pressure from below. To attribute them in any way to subsidence seems almost a paradox, and yet it appears to be now well established that the general cause is lateral compression, due to contraction of the underlying mass. The earth, we know, has been gradually cooling, and as it contracted in doing so, the strata of the crust would necessarily be thrown into folds. When an apple dries and shrivels in winter, the surface becomes covered with ridges. Or again, if we place some sheets of paper between two weights on a table, and then bring the weights nearer together, the paper will be crumpled up.



In the same way let us take a section of the earth's surface AB (Fig. 17), and suppose that, by the gradual cooling and consequent contraction of the mass, AB sinks to A'B', then to A''B'', and finally to A'''B'''. Of course if the cooling of the surface and of the deeper portion were the same, then the strata between A and B would themselves contract, and might consequently still form a regular curve between A''' and B'''. As a matter of fact, however, the strata at the surface of our globe have long since approached a constant temperature. Under these circumstances there would be no contraction of the strata between A and B corresponding to that of those in the interior, and consequently they could not lie flat between A''' and B''', but must be thrown into folds, commencing along any line of least resistance. Sometimes indeed the strata are completely inverted, as in Fig. 19, and in other cases they have been squeezed for miles out of their original position. This explanation was first, I believe, suggested by Steno. It has been recently developed by Ball and Suess, and especially by Heim. In this manner it is probable that most mountain chains originated.[43]

The structure of mountain districts confirms this theoretical explanation. It is obvious of course that when strata are thrown into folds, they will, if strained too much, give way at the summit of the fold. Before doing so, however, they are stretched and consequently loosened, while on the other hand the strata at the bottom of the fold are compressed: the former, therefore, are rendered more susceptible of disintegration, the latter on the contrary acquire greater powers of resistance. Hence denudation will act with more effect on the upper than on the lower portion of the folds, and if continued long enough, so that, as shown in the above diagram, the dotted portion is removed, we find the original hill tops replaced by valleys, and the original valleys forming the hill tops. Every visitor to Switzerland must have noticed hills where the strata lie as shown in parts of Fig. 18, and where it is obvious that strata corresponding to those in dots must have been originally present.

In the Jura, for instance, a glance at any good map of the district will show a succession of ridges running parallel to one another in a slightly curved line from S.W. to N.E. That these ridges are due to folds of the earth's surface is clear from the following figure in Jaccard's work on the Geology of the Jura, showing a section from Brenets due south to Neuchatel by Le Locle. These folds are comparatively slight and the hills of no great height. Further south, however, the strata are much more violently dislocated and compressed together. The Mont Saleve is the remnant of one of these ridges.



In the Alps the contortions are much greater than in the Jura. Fig. 19 shows a section after Heim, from the Spitzen across the Brunnialp, and the Maderanerthal. It is obvious that the valleys are due mainly to erosion, that the Maderaner valley has been cut out of the crystalline rocks s, and was once covered by the Jurassic strata j, which must have formerly passed in a great arch over what is now the valley.

However improbable it may seem that so great an amount of rock should have disappeared, evidence is conclusive. Ramsay has shown that in some parts of Wales not less than 29,000 feet have been removed, while there is strong reason for the belief that in Switzerland an amount has been carried away equal to the present height of the mountains; though of course it does not follow that the Alps were once twice as high as they are at present, because elevation and erosion must have gone on contemporaneously.



It has been calculated that the strata between Bale and the St. Gotthard have been compressed from 202 miles to 130 miles, the Ardennes from 50 to 25 miles, and the Appalachians from 153 miles to 65! Prof. Gumbel has recently expressed the opinion that the main force to which the elevation of the Alps was due acted along the main axis of elevation. Exactly the opposite inference would seem really to follow from the facts. If the centre of force were along the axis of elevation, the result would, as Suess and Heim have pointed out, be to extend, not to compress, the strata; and the folds would remain quite unaccounted for. The suggestion of compression is on the contrary consistent with the main features of Swiss geography. The principal axis follows a curved line from the Maritime Alps towards the north-east by Mont Blanc and Monte Rosa and St. Gotthard to the mountains overlooking the Engadine. The geological strata follow the same direction. North of a line running through Chambery, Yverdun, Neuchatel, Solothurn, and Olten to Waldshut on the Rhine are Jurassic strata; between that line and a second nearly parallel and running through Annecy, Vevey, Lucerne, Wesen, Appenzell, and Bregenz on the Lake of Constance, is the lowland occupied by later Tertiary strata; between this second line and another passing through Albertville, St. Maurice, Lenk, Meiringen, and Altdorf lies a more or less broken band of older Tertiary strata; south of which are a Cretaceous zone, one of Jurassic age, then a band of crystalline rocks, while the central core, so to say, of the Alps, as for instance at St. Gotthard, consists mainly of gneiss or granite. The sedimentary deposits reappear south of the Alps, and in the opinion of some high authorities, as, for instance, of Bonney and Heim, passed continuously over the intervening regions. The last great upheaval commenced after the Miocene period, and continued through the Pliocene. Miocene strata attain in the Righi a height of 6000 feet.

For neither the hills nor the mountains are everlasting, or of the same age.

The Welsh mountains are older than the Vosges, the Vosges than the Pyrenees, the Pyrenees than the Alps, and the Alps than the Andes, which indeed are still rising; so that if our English mountains are less imposing so far as mere height is concerned, they are most venerable from their great antiquity.

But though the existing Alps are in one sense, and speaking geologically, very recent, there is strong reason for believing that there was a chain of lofty mountains there long previously. "The first indication," says Judd, "of the existence of a line of weakness in this portion of the earth's crust is found towards the close of the Permian period, when a series of volcanic outbursts on the very grandest scale took place" along a line nearly following that of the present Alps, and led to the formation of a range of mountains, which, in his opinion, must have been at least 8000 to 9000 feet high. Ramsay and Bonney have also given strong reasons for believing that the present line of the Alps was, at a still earlier period, occupied by a range of mountains no less lofty than those of to-day. Thus then, though the present Alps are comparatively speaking so recent, there are good grounds for the belief that they were preceded by one or more earlier ranges, once as lofty as they are now, but which were more or less completely levelled by the action of air and water, just as is happening now to the present mountain ranges.

Movements of elevation and subsidence are still going on in various parts of the world. Scandinavia is rising in the north, and sinking at the south. South America is rising on the west and sinking in the east, rotating in fact on its axis, like some stupendous pendulum.

The crushing and folding of the strata to which mountain chains are due, and of which the Alps afford such marvellous illustrations, necessarily give rise to Earthquakes, and the slight shocks so frequent in parts of Switzerland[44] appear to indicate that the forces which have raised the Alps are not yet entirely spent, and that slow subterranean movements are still in progress along the flanks of the mountains.

But if the mountain chains are due to compression, the present valleys are mainly the result of denudation. As soon as a mountain range is once raised, all nature seems to conspire against it. Sun and Frost, Heat and Cold, Air and Water, Ice and Snow, every plant, from the Lichen to the Oak, and every animal, from the Worm to Man himself, combine to attack it. Water, however, is the most powerful agent of all. The autumn rains saturate every pore and cranny; the water as it freezes cracks and splits the hardest rocks; while the spring sun melts the snow and swells the rivers, which in their turn carry off the debris to the plains.

Perhaps, however, it would after all be more correct to say that Nature, like some great artist, carves the shapeless block into form, and endows the rude mass with life and beauty.

"What more," said Hutton long ago, "is required to explain the configuration of our mountains and valleys? Nothing but time. It is not any part of the process that will be disputed; but, after allowing all the parts, the whole will be denied; and for what? Only because we are not disposed to allow that quantity of time which the absolution of so much wasted mountain might require."

The tops of the Swiss mountains stand, and since their elevation have probably always stood, above the range of ice, and hence their bold peaks. In Scotland, on the contrary, and still more in Norway, the sheet of ice which once, as is the case with Greenland now, spread over the whole country, has shorn off the summits and reduced them almost to gigantic bosses; while in Wales the same causes, together with the resistless action of time—for, as already mentioned, the Welsh hills are far older than the mountains of Switzerland—has ground down the once lofty summits and reduced them to mere stumps, such as, if the present forces are left to work out their results, the Swiss mountains will be thousands, or rather tens of thousands, of years hence.

The "snow line" in Switzerland is generally given as being between 8500 and 9000 feet. Above this level the snow or neve gradually accumulates until it forms "glaciers," solid rivers of ice which descend more or less far down the valleys. No one who has not seen a glacier can possibly realise what they are like. Fig. 20 represents the glacier of the Bluemlis Alp, and the Plate the Mer de Glace.



They are often very beautiful. "Mount Beerenberg," says Lord Dufferin, "in size, colour, and effect far surpassed anything I had anticipated. The glaciers were quite an unexpected element of beauty. Imagine a mighty river, of as great a volume as the Thames, started down the side of a mountain, bursting over every impediment, whirled into a thousand eddies, tumbling and raging on from ledge to ledge in quivering cataracts of foam, then suddenly struck rigid by a power so instantaneous in its action that even the froth and fleeting wreaths of spray have stiffened to the immutability of sculpture. Unless you had seen it, it would be almost impossible to conceive the strangeness of the contrast between the actual tranquillity of these silent crystal rivers and the violent descending energy impressed upon their exterior. You must remember too all this is upon a scale of such prodigious magnitude, that when we succeeded subsequently in approaching the spot—where with a leap like that of Niagara one of these glaciers plunges down into the sea—the eye, no longer able to take in its fluvial character, was content to rest in simple astonishment at what then appeared a lucent precipice of grey-green ice, rising to the height of several hundred feet above the masts of the vessel."[45]

The cliffs above glaciers shower down fragments of rock which gradually accumulate at the sides and at the end of the glaciers, forming mounds known as "moraines." Many ancient moraines occur far beyond the present region of glaciers.

In considering the condition of alpine valleys we must remember that the glaciers formerly descended much further than they do at present. The glaciers of the Rhone for instance occupied the whole of the Valais, filled the Lake of Geneva—or rather the site now occupied by that lake—and rose 2000 feet up the slopes of the Jura; the Upper Ticino, and contributory valleys, were occupied by another which filled the basin of the Lago Maggiore; a third occupied the valley of the Dora Baltea, and has left a moraine at Ivrea some twenty miles long, and which rises no less than 1500 feet above the present level of the river. The Scotch and Scandinavian valleys were similarly filled by rivers of ice, which indeed at one time covered the whole country with an immense sheet, as Greenland is at present. Enormous blocks of stone, the Pierre a Niton at Geneva and the Pierre a Bot above Neuchatel, for instance, were carried by these glaciers for miles and miles; and many of the stones in the Norfolk cliffs were brought by ice from Norway (perhaps, however, by Icebergs), across what is now the German Ocean. Again wherever the rocks are hard enough to have withstood the weather, we find them polished and ground, just as, and even more so than, those at the ends and sides of existing glaciers.

The most magnificent glacier tracks in the Alps are, in Ruskin's opinion, those on the rocks of the great angle opposite Martigny; the most interesting those above the channel of the Trient between Valorsine and the valley of the Rhone.

In Great Britain I know no better illustration of ice action than is to be seen on the road leading down from Glen Quoich to Loch Hourn, one of the most striking examples of desolate and savage scenery in Scotland. Its name in Celtic is said to mean the Lake of Hell. All along the roadside are smoothed and polished hummocks of rock, most of them deeply furrowed with approximately parallel striae, presenting a gentle slope on the upper end, and a steep side below, clearly showing the direction of the great ice flow.

Many of the upper Swiss valleys contain lakes, as, for instance, that of the Upper Rhone, the Lake of Geneva, of the Reuss, the Lake of Lucerne, of the Rhine, that of Constance. These lakes are generally very deep.

The colour of the upper rivers, which are white with the diluvium from the glaciers, is itself evidence of the erosive powers which they exercise. This finely-divided matter is, however, precipitated in the lakes, which, as well as the rivers issuing from them, are a beautiful rich blue.

"Is it not probable that this action of finely-divided matter may have some influence on the colour of some of the Swiss lakes—as that of Geneva for example? This lake is simply an expansion of the river Rhone, which rushes from the end of the Rhone glacier, as the Arveiron does from the end of the Mer de Glace. Numerous other streams join the Rhone right and left during its downward course; and these feeders, being almost wholly derived from glaciers, join the Rhone charged with the finer matter which these in their motion have ground from the rocks over which they have passed. But the glaciers must grind the mass beneath them to particles of all sizes, and I cannot help thinking that the finest of them must remain suspended in the lake throughout its entire length. Faraday has shown that a precipitate of gold may require months to sink to the bottom of a bottle not more than five inches high, and in all probability it would require ages of calm subsidence to bring all the particles which the Lake of Geneva contains to its bottom. It seems certainly worthy of examination whether such particles suspended in the water contribute to the production of that magnificent blue which has excited the admiration of all who have seen it under favourable circumstances."[46]

Among the Swiss mountains themselves each has its special character. Tyndall thus describes a view in the Alps, certainly one of the most beautiful—that, namely, from the summit of the AEgischhorn.

"Skies and summits are to-day without a cloud, and no mist or turbidity interferes with the sharpness of the outlines. Jungfrau, Monk, Eiger, Trugberg, cliffy Strahlgrat, stately lady-like Aletschhorn, all grandly pierce the empyrean. Like a Saul of Mountains, the Finsteraarhorn overtops all his neighbours; then we have the Oberaarhorn, with the riven glacier of Viesch rolling from his shoulders. Below is the Marjelin See, with its crystal precipices and its floating icebergs, snowy white, sailing on a blue green sea. Beyond is the range which divides the Valais from Italy. Sweeping round, the vision meets an aggregate of peaks which look as fledglings to their mother towards the mighty Dom. Then come the repellent crags of Mont Cervin; the ideal of moral savagery, of wild untameable ferocity, mingling involuntarily with our contemplation of the gloomy pile. Next comes an object, scarcely less grand, conveying, it may be, even a deeper impression of majesty and might than the Matterhorn itself—the Weisshorn, perhaps the most splendid object in the Alps. But beauty is associated with its force, and we think of it, not as cruel, but as grand and strong. Further to the right the great Combin lifts up his bare head; other peaks crowd around him; while at the extremity of the curve round which our gaze has swept rises the sovran crown of Mont Blanc. And now, as day sinks, scrolls of pearly clouds draw themselves around the mountain crests, being wafted from them into the distant air. They are without colour of any kind; still, by grace of form, and as the embodiment of lustrous light and most tender shade, their beauty is not to be described."[47]

VOLCANOES

Volcanoes belong to a totally different series of mountains.

It is practically impossible to number the Volcanoes on our earth. Humboldt enumerated 223, which Keith Johnston raised to nearly 300. Some, no doubt, are always active, but in the majority the eruptions are occasional, and though some are undoubtedly now extinct, it is impossible in all cases to distinguish those which are only in repose from those whose day of activity is over. Then, again, the question would arise, which should be regarded as mere subsidiary cones and which are separate volcanoes. The slopes of Etna present more than 700 small cones, and on Hawaii there are several thousands. In fact, most of the very lofty volcanoes present more or less lateral cones.

The molten matter, welling up through some fissure, gradually builds itself up into a cone, often of the most beautiful regularity, such as the gigantic peaks of Chimporazo, Cotopaxi (Fig. 21), and Fusiyama, and hence it is that the crater is so often at, or very near, the summit.



Perhaps no spectacle in Nature is more magnificent than a Volcano in activity. It has been my good fortune to have stood more than once at the edge of the crater of Vesuvius during an eruption, to have watched the lava seething below, while enormous stones were shot up high into the air. Such a spectacle can never be forgotten.

The most imposing crater in the world is probably that of Kilauea, at a height of about 4000 feet on the side of Mouna Loa, in the Island of Hawaii. It has a diameter of 2 miles, and is elliptic in outline, with a longer axis of about 3, and a circumference of about 7 miles. The interior is a great lake of lava, the level of which is constantly changing. Generally, it stands about 800 feet below the edge, and the depth is about 1400 feet. The heat is intense, and, especially at night, when the clouds are coloured scarlet by the reflection from the molten lava, the effect is said to be magnificent. Gradually the lava mounts in the crater until it either bursts through the side or runs over the edge, after which the crater remains empty, sometimes for years.

A lava stream flows down the slope of the mountain like a burning river, at first rapidly, but as it cools, scoriae gradually form, and at length the molten matter covers itself completely (Fig. 22), both above and at the sides, with a solid crust, within which, as in a tunnel, it continues to flow slowly as long as it is supplied from the source, here and there breaking through the crust which, as continually, re-forms in front. Thus the terrible, inexorable river of fire slowly descends, destroying everything in its course.



The stream of lava which burst from Mouna Loa in 1885 had a length of 70 miles; that of Skaptar-Jokul in Iceland in 1783 had a length of 50 miles, and a maximum depth of nearly 500 feet. It has been calculated that the mass of lava equalled that of Mont Blanc.

The stones, ashes, and mud ejected during eruptions are even more destructive than the rivers of lava. In 1851 Tomboro, a volcano on the Island of Sumbava, cost more lives than fell in the battle of Waterloo. The earthquake of Lisbon in 1755 destroyed 60,000 persons. During the earthquake of Riobamba and the mud eruption of Tunguragua, and again in that of Krakatoa, it is estimated that the number who perished was between 30,000 and 40,000. At the earthquake of Antioch in 526 no less than 200,000 persons are said to have lost their lives.

Perhaps the most destructive eruption of modern times has been that on Cosequina. For 25 miles it covered the ground with muddy water 16 feet in depth. The dust and ashes formed a dense cloud, extending over many miles, some of it being carried 20 degrees to the west. The total mass ejected has been estimated at 60 milliards of square yards.

Stromboli, in the Mediterranean (Fig. 23), though only 2500 feet in height, is very imposing from its superb regularity, and its roots plunge below the surface to a depth of 4000 feet.

It is, moreover, very interesting from the regularity of its action, which has a period of 5 minutes or a little less. On looking down into the crater one sees at a depth of say 300 feet a seething mass of red-hot lava; this gradually rises, and then explodes, throwing up a cloud of vapour and stones, after which it sinks again. So regular is it that the Volcano has been compared to a "flashing" lighthouse, and this wonderful process has been going on for ages.



Though long extinct, volcanoes once existed in the British Isles; Arthur's Seat, near Edinburgh, for instance, appears to be the funnel of a small volcano, belonging to the Carboniferous period.

The summit of a volcanic mountain is sometimes entirely blown away. Between my first two visits to Vesuvius 200 feet of the mountain had thus disappeared. Vesuvius itself stands in a more ancient crater, part of which still remains, and is now known as Somma, the greater portion having disappeared in the great eruption of 79, when the mountain, waking from its long sleep, destroyed Herculaneum and Pompeii.

As regards the origin of volcanoes there have been two main theories. Impressed by the magnitude and grandeur of the phenomena, enhanced as they are by their destructive character, many have been disposed to regard the craters of volcanoes as gigantic chimneys, passing right through the solid crust of the globe, and communicating with a central fire. Recent researches, however, have indicated that, grand and imposing as they are, volcanoes must yet be regarded as due mainly to local and superficial causes.

A glance at the map shows that volcanoes are almost always situated on, or near, the sea coast. From the interior of continents they are entirely wanting. The number of active volcanoes in the Andes, contrasted with their absence in the Alps and Ourals, the Himalayas, and Central Asian chains, is very striking. Indeed, the Pacific Ocean is encircled, as Ritter has pointed out, by a ring of fire. Beginning with New Zealand, we have the Volcanoes of Tongariro, Whakaii, etc.; thence the circle passes through the Fiji Islands, Solomon Islands, New Guinea, Timor, Flores, Sumbava, Lombock, Java, Sumatra, the Philippines, Japan, the Aleutian Islands, along the Rocky Mountains, Mexico, Peru, and Chili, to Tierra del Fuego, and, in the far south, to the two great Volcanoes of Erebus and Terror on Victoria Land.

We know that the contraction of the Earth's surface with the strains and fractures, the compression and folds, which must inevitably result, is still in operation, and must give rise to areas of high temperature, and consequently to volcanoes. We must also remember that the real mountain chains of our earth are the continents, compared to which even the Alps and Andes are mere wrinkles. It is along the lines of the great mountain chains, that is to say, along the main coast lines, rather than in the centres of the continents, which may be regarded as comparatively quiescent, that we should naturally expect to find the districts of greatest heat, and this is perhaps why volcanoes are generally distributed along the coast lines.

Another reason for regarding Volcanoes as local phenomena is that many even of those comparatively near one another act quite independently. This is so with Kilauea and Mouna Loa, both on the small island of Hawaii.

Again, if volcanoes were in connection with a great central sea of fire, the eruptions must follow the same laws as regulate the tides. This, however, is not the case. There are indeed indications of the existence of slight tides in the molten lake which underlies Vesuvius, and during the eruption of 1865 there was increased activity twice a day, as we should expect to find in any great fluid reservoir, but very different indeed from what must have been the case if the mountain was in connection with a central ocean of molten matter.

Indeed, unless the "crust" of our earth was of great thickness we should be subject to perpetual earthquakes. No doubt these are far more frequent than is generally supposed; indeed, with our improved instruments it can be shown that instead of occasional vibrations, with long intermediate periods of rest, we have in reality short intervals of rest with long periods of vibration, or rather perhaps that the crust of the earth is in constant tremor, with more violent oscillation from time to time.

It appears, moreover, that earthquakes are not generally deep-seated. The point at which the shock is vertical can be ascertained, and it is also possible in some cases to determine the angle at which it emerges elsewhere. When this has been done it has always been found that the seat of disturbance must have been within 30 geographical miles of the surface.

Yet, though we cannot connect volcanic action with the central heat of the earth, but must regard it as a minor and local manifestation of force, volcanoes still remain among the grandest, most awful, and at the same time most magnificent spectacles which the earth can afford.

FOOTNOTES:

[38] Ruskin.

[39] The Glaciers of the Alps.

[40] Ossian.

[41] Bullar, Azores.

[42] Tennyson.

[43] See especially Heim's great work, Unt. ue. d. Mechanismus der Gebirgsbildung.

[44] In the last 150 years more than 1000 are recorded.

[45] Letters from High Latitudes.

[46] Glaciers of the Alps.

[47] Mountaineering in 1861.



CHAPTER VII

WATER

Of all inorganic substances, acting in their own proper nature, and without assistance or combination, water is the most wonderful. If we think of it as the source of all the changefulness and beauty which we have seen in the clouds; then as the instrument by which the earth we have contemplated was modelled into symmetry, and its crags chiselled into grace; then as, in the form of snow, it robes the mountains it has made, with that transcendent light which we could not have conceived if we had not seen; then as it exists in the foam of the torrent, in the iris which spans it, in the morning mist which rises from it, in the deep crystalline pools which mirror its hanging shore, in the broad lake and glancing river, finally, in that which is to all human minds the best emblem of unwearied, unconquerable power, the wild, various, fantastic, tameless unity of the sea; what shall we compare to this mighty, this universal element, for glory and for beauty? or how shall we follow its eternal cheerfulness of feeling? It is like trying to paint a soul.—RUSKIN.



CHAPTER VII

WATER

In the legends of ancient times running water was proof against all sorcery and witchcraft:

No spell could stay the living tide Or charm the rushing stream.[48]

There was much truth as well as beauty in this idea.

Flowing waters, moreover, have not only power to wash out material stains, but they also clear away the cobwebs of the brain—the results of over incessant work—and restore us to health and strength.

Snowfields and glaciers, mountain torrents, sparkling brooks, and stately rivers, meres and lakes, and last, not least, the great ocean itself, all alike possess this magic power.

"When I would beget content," says Izaak Walton, "and increase confidence in the power and wisdom and providence of Almighty God, I will walk the meadows by some gliding stream, and there contemplate the lilies that take no care, and those very many other little living creatures that are not only created, but fed (man knows not how) by the goodness of the God of Nature, and therefore trust in Him;" and in his quaint old language he craves a special blessing on all those "that are true lovers of virtue, and dare trust in His Providence, and be quiet, and go a angling."

At the water's edge flowers are especially varied and luxuriant, so that the banks of a river are a long natural garden of tall and graceful grasses and sedges, the Meadow Sweet, the Flowering Rush, the sweet Flag, the Bull Rush, Purple Loosestrife, Hemp Agrimony, Dewberry, Forget-me-not, and a hundred more, backed by Willows, Alders, Poplars, and other trees.

The Animal world, if less conspicuous to the eye, is quite as fascinating to the imagination. Here and there a speckled Trout may be detected (rather by the shadow than the substance) suspended in the clear water, or darting across a shallow; if we are quiet we may see Water Hens or Wild Ducks swimming among the lilies, a Kingfisher sitting on a branch or flashing away like a gleam of light; a solemn Heron stands maybe at the water's edge, or slowly rises flapping his great wings; Water Rats, neat and clean little creatures, very different from their coarse brown namesakes of the land, are abundant everywhere; nor need we even yet quite despair of seeing the Otter himself.

Insects of course are gay, lively, and innumerable; but after all the richest fauna is that visible only with a microscope.

"To gaze," says Dr. Hudson, "into that wonderful world which lies in a drop of water, crossed by some stems of green weed, to see transparent living mechanism at work, and to gain some idea of its modes of action, to watch a tiny speck that can sail through the prick of a needle's point; to see its crystal armour flashing with ever varying tint, its head glorious with the halo of its quivering cilia; to see it gliding through the emerald stems, hunting for its food, snatching at its prey, fleeing from its enemy, chasing its mate (the fiercest of our passions blazing in an invisible speck); to see it whirling in a mad dance, to the sound of its own music, the music of its happiness, the exquisite happiness of living—can any one, who has once enjoyed this sight, ever turn from it to mere books and drawings, without the sense that he has left all Fairyland behind him?"[49]

The study of Natural History has indeed the special advantage of carrying us into the country and the open air.

Lakes are even more restful than rivers or the sea. Rivers are always flowing, though it may be but slowly; the sea may rest awhile, now and then, but is generally full of action and energy; while lakes seem to sleep and dream. Lakes in a beautiful country are like silver ornaments on a lovely dress, like liquid gems in a beautiful setting, or bright eyes in a lovely face. Indeed as we gaze down on a lake from some hill or cliff it almost looks solid, like some great blue crystal.



It is not merely for purposes of commerce or convenience that men love to live near rivers.

Let me live harmlessly, and near the brink Of Trent or Avon have my dwelling-place; Where I may see my quill, or cork, down sink, With eager bite of pike, or bleak, or dace; And on the world and my Creator think: While some men strive ill-gotten goods t' embrace: And others spend their time in base excess Of wine; or worse, in war, or wantonness.

Let them that will, these pastimes still pursue, And on such pleasing fancies feed their fill: So I the fields and meadows green may view And daily by fresh rivers walk at will, Among the daisies and the violets blue, Red hyacinth and yellow daffodil.[50]

It is interesting and delightful to trace a river from its source to the sea.

"Beginning at the hill-tops," says Geikie, "we first meet with the spring or 'well-eye,' from which the river takes its rise. A patch of bright green, mottling the brown heathy slope, shows where the water comes to the surface, a treacherous covering of verdure often concealing a deep pool beneath. From this source the rivulet trickles along the grass and heath, which it soon cuts through, reaching the black, peaty layer below, and running in it for a short way as in a gutter. Excavating its channel in the peat, it comes down to the soil, often a stony earth bleached white by the peat. Deepening and widening the channel as it gathers force with the increasing slope, the water digs into the coating of drift or loose decomposed rock that covers the hillside. In favourable localities a narrow precipitous gully, twenty or thirty feet deep, may thus be scooped out in the course of a few years."

If, however, we trace one of the Swiss rivers to its source we shall generally find that it begins in a snow field or neve nestled in a shoulder of some great mountain.

Below the neve lies a glacier, on, in, and under which the water runs in a thousand little streams, eventually emerging at the end, in some cases forming a beautiful blue cavern, though in others the end of the glacier is encumbered and concealed by earth and stones.



The uppermost Alpine valleys are perhaps generally, though by no means always, a little desolate and severe, as, for instance, that of St. Gotthard (Fig. 24). The sides are clothed with rough pasture, which is flowery indeed, though of course the flowers are not visible at a distance, interspersed with live rock and fallen masses, while along the bottom rushes a white torrent. The snowy peaks are generally more or less hidden by the shoulders of the hills.

The valleys further down widen and become more varied and picturesque. The snowy peaks and slopes are more often visible, the "alps" or pastures to which the cows are taken in summer, are greener and dotted with the huts or chalets of the cow-herds, while the tinkling of the cowbells comes to one from time to time, softened by distance, and suggestive of mountain rambles. Below the alps there is generally a steeper part clothed with Firs or with Larches and Pines, some of which seem as if they were scaling the mountains in regiments, preceded by a certain number of skirmishers. Below the fir woods again are Beeches, Chestnuts, and other deciduous trees, while the central cultivated portion of the valley is partly arable, partly pasture, the latter differing from our meadows in containing a greater variety of flowers—Campanulas, Wild Geraniums, Chervil, Ragged Robin, Narcissus, etc. Here and there is a brown village, while more or less in the centre hurries along, with a delightful rushing sound, the mountain torrent, to which the depth, if not the very existence of the valley, is mainly due. The meadows are often carefully irrigated, and the water power is also used for mills, the streams seeming to rush on, as Ruskin says, "eager for their work at the mill, or their ministry to the meadows."

Apart from the action of running water, snow and frost are continually disintegrating the rocks, and at the base of almost any steep cliff may be seen a slope of debris (as in Figs. 25, 26). This stands at a regular angle—the angle of repose—and unless it is continually removed by a stream at the base, gradually creeps up higher and higher, until at last the cliff entirely disappears.



Sometimes the two sides of the valley approach so near that there is not even room for the river and the road: in that case Nature claims the supremacy, and the road has to be carried in a cutting, or perhaps in a tunnel through the rock. In other cases Nature is not at one with herself. In many places the debris from the rocks above would reach right across the valley and dam up the stream. Then arises a struggle between rock and river, but the river is always victorious in the end; even if dammed back for a while, it concentrates its forces, rises up the rampart of rock, rushes over triumphantly, resumes its original course, and gradually carries the enemy away.



Another prominent feature in many valleys is afforded by the old river, or lake, terraces, which were formed at a time when the river ran at a level far above its present bed.

Thus many a mountain valley gives some such section as the following.



First, a face of rock, very steep, and in some places almost perpendicular; secondly, a regular talus of fallen rocks, stones, etc., as shown in the view of the Rhone Valley (Fig. 26), which takes what is known as the slope of repose, at an angle which depends on the character of the material. As a rule for loose rock fragments it may be taken roughly to be an angle of about 45 deg.. Then an irregular slope followed in many places by one or more terraces, and lastly the present bed of the river.



The width or narrowness of the valley in relation to its depth depends greatly on the condition of the rocks, the harder and tougher they are the narrower as a rule being the valley.

From time to time a side stream enters the main valley. This is itself composed of many smaller rivulets. If the lateral valleys are steep, the streams bring with them, especially after rains, large quantities of earth and stones. When, however, they reach the main valley, the rapidity of the current being less, their power of transport also diminishes, and they spread out the material which they carry down in a depressed cone (Figs. 28, 29, 31, 32).

A side stream with its terminal cone, when seen from the opposite side of the valley, presents the appearance shown in Figs. 28, 31, or, if we are looking down the valley, as in Figs. 29, 32, the river being often driven to one side of the main valley, as, for instance, is the case in the Valais, near Sion, where the Rhone (Fig. 30) is driven out of its course by, and forms a curve round, the cone brought down by the torrent of the Borgne.



Sometimes two lateral valleys (see Plate) come down nearly opposite one another, so that the cones meet, as, for instance, some little way below Vernayaz, and, indeed, in several other places in the Valais (Fig. 31). Or more permanent lakes may be due to a ridge of rock running across the valley, as, for instance, just below St. Maurice in the Valais.



Almost all river valleys contain, or have contained, in their course one or more lakes, and where a river falls into a lake a cone like those just described is formed, and projects into the lake. Thus on the Lake of Geneva, between Vevey and Villeneuve (see Fig. 33), there are several such promontories, each marking the place where a stream falls into the lake.



The Rhone itself has not only filled up what was once the upper end of the lake, but has built out a strip of land into the water.



That the lake formerly extended some distance up the Valais no one can doubt who looks at the flat ground about Villeneuve. The Plate opposite, from a photograph taken above Vevey, shows this clearly. It is quite evident that the lake must formerly have extended further up the valley, and that it has been filled up by material brought down by the Rhone, a process which is still continuing.

At the other end of the lake the river rushes out 15 feet deep of "not flowing, but flying water; not water neither—melted glacier matter, one should call it; the force of the ice is in it, and the wreathing of the clouds, the gladness of the sky, and the countenance of time."[51]



In flat countries the habits of rivers are very different. For instance, in parts of Norfolk there are many small lakes or "broads" in a network of rivers—the Bure, the Yare, the Ant, the Waveney, etc.—which do not rush on with the haste of some rivers, or the stately flow of others which are steadily set to reach the sea, but rather seem like rivers wandering in the meadows on a holiday. They have often no natural banks, but are bounded by dense growths of tall grasses, Bulrushes, Reeds, and Sedges, interspersed with the spires of the purple Loosestrife, Willow Herb, Hemp Agrimony, and other flowers, while the fields are very low and protected by dykes, so that the red cattle appear to be browsing below the level of the water; and as the rivers take most unexpected turns, the sailing boats often seem (Fig. 34) as if they were in the middle of the fields.



At present these rivers are restrained in their courses by banks; when left free they are continually changing their beds. Their courses at first sight seem to follow no rule, but, as it is termed, from a celebrated river of Asia Minor, to "meander" along without aim or object, though in fact they follow very definite laws.

Finally, when the river at length reaches the sea, it in many cases spreads out in the form of a fan, forming a very flat cone or "delta," as it is called, from the Greek capital [Greek: Delta], a name first applied to that of the Nile, and afterwards extended to other rivers. This is due to the same cause, and resembles, except in size, the comparatively minute cones of mountain streams.



Fig. 35 represents the delta of the Po, and it will be observed that Adria, once a great port, and from which the Adriatic was named, is now more than 20 miles from the sea. Perhaps the most remarkable case is that of the Mississippi (Fig. 36), the mouths of which project into the sea like a hand, or like the petals of a flower. For miles the mud is too soft to support trees, but is covered by sedges (Miegea); the banks of mud gradually become too soft and mobile even for them. The pilots who navigate ships up the river live in frail houses resting on planks, and kept in place by anchors. Still further, and the banks of the Mississippi, if banks they can be called, are mere strips of reddish mud, intersected from time to time by transverse streams of water, which gradually separate them into patches. These become more and more liquid, until the land, river, and sea merge imperceptibly into one another. The river is so muddy that it might almost be called land, and the mud so saturated by water that it might well be called sea, so that one can hardly say whether a given spot is on the continent, in the river, or on the open ocean.



FOOTNOTES:

[48] Leyden.

[49] Dr. Hudson, Address to the Microscopical Society, 1889.

[50] F. Davors.

[51] Ruskin.



CHAPTER VIII

RIVERS AND LAKES

ON THE DIRECTIONS OF RIVERS

In the last chapter I have alluded to the wanderings of rivers within the limits of their own valleys; we have now to consider the causes which have determined the directions of the valleys themselves.

If a tract of country were raised up in the form of a boss or dome, the rain which fell on it would partly sink in, partly run away to the lower ground. The least inequality in the surface would determine the first directions of the streams, which would carry down any loose material, and thus form little channels, which would be gradually deepened and enlarged. It is as difficult for a river as for a man to get out of a groove.

In such a case the rivers would tend to radiate with more or less regularity from the centre or axis of the dome, as, for instance, in our English lake district (Fig. 37). Derwent Water, Thirlmere, Coniston Water, and Windermere, run approximately N. and S.; Crummock Water, Loweswater, and Buttermere N.W. by S.E.; Waste Water, Ullswater, and Hawes Water N.E. by S.W.; while Ennerdale Water lies nearly E. by W. Can we account in any way, and if so how, for these varied directions?

The mountains of Cumberland and Westmoreland form a more or less oval boss, the axis of which, though not straight, runs practically from E.N.E. to W.S.W., say from Scaw Fell to Shap Fell; and a sketch map shows us almost at a glance that Derwent Water, Thirlmere, Ullswater, Coniston Water, and Windermere run at right angles to this axis; Ennerdale Water is just where the boss ends and the mountains disappear; while Crummock Water and Waste Water lie at the intermediate angles.



So much then for the direction. We have still to consider the situation and origin, and it appears that Ullswater, Coniston Water, the River Dudden, Waste Water, and Crummock Water lie along the lines of old faults, which no doubt in the first instance determined the flow of the water.

Take another case. In the Jura the valleys are obviously (see Fig. 18) in many cases due to the folding of the strata. It seldom happens, however, that the case is so simple. If the elevation is considerable the strata are often fractured, and fissures are produced. Again if the part elevated contains layers of more than one character, this at once establishes differences. Take, for instance, the Weald of Kent (Figs. 38, 39). Here we have (omitting minor layers) four principal strata concerned, namely, the Chalk, Greensand, Weald Clay, and Hastings Sands.



The axis of elevation runs (Fig. 39) from Winchester by Petersfield, Horsham, and Winchelsea to Boulogne, and as shown in the following section, taken from Professor Ramsay, we have on each side of the axis two ridges or "escarpments," one that of the Chalk, the other that of the Greensand, while between the Chalk and the Greensand is a valley, and between the Greensand and the ridge of Hastings Sand an undulating plain, in each case with a gentle slope from about where the London and Brighton railway crosses the Weald towards the east. Under these circumstances we might have expected that the streams draining the Weald would have run in the direction of the axis of elevation, and at the bases of the escarpments, as in fact the Rother does for part of its course, into the sea between the North and South Downs, instead of which as a rule they run north and south, cutting in some cases directly through the escarpments; on the north, for instance, the Wye, the Mole, the Darenth, the Medway, and the Stour; and on the south the Arun, the Addur, the Ouse, and the Cuckmere.



They do not run in faults or cracks, and it is clear that they could not have excavated their present valleys under circumstances such as now exist. They carry us back indeed to a time when the Greensand and Chalk were continued across the Weald in a great dome, as shown by the dotted lines in Fig. 38. They then ran down the slope of the dome, and as the Chalk and Greensand gradually weathered back, a process still in operation, the rivers deepened and deepened their valleys, and thus were enabled to keep their original course.

Other evidence in support of this view is afforded by the presence of gravel beds in some places at the very top of the Chalk escarpment—beds which were doubtless deposited when, what is now the summit of a hill, was part of a continuous slope.

The course of the Thames offers us a somewhat similar instance. It rises on the Oolites near Cirencester, and cuts through the escarpment of the Chalk between Wallingford and Reading. The cutting through the Chalk has evidently been effected by the river itself. But this could not have happened under existing conditions. We must remember, however, that the Chalk escarpment is gradually moving eastwards. The Chalk escarpments indeed are everywhere, though of course only slowly, crumbling away. Between Farnham and Guildford the Chalk is reduced to a narrow ridge known as the Hog's Back. In the same way no doubt the area of the Chalk formerly extended much further west than it does at present, and, indeed, there can be little doubt, somewhat further west than the source of the Thames, almost to the valley of the Severn. At that time the Thames took its origin in a Chalk spring. Gradually, however, the Chalk was worn away by the action of weather, and especially of rain. The river maintained its course while gradually excavating, and sinking deeper and deeper into, the Chalk. At present the river meets the Chalk escarpment near Wallingford, but the escarpment itself is still gradually retreating eastward.

So, again, the Elbe cuts right across the Erz-Gebirge, the Rhine through the mountains between Bingen and Coblenz, the Potomac, the Susquehannah, and the Delaware through the Alleghanies. The case of the Dranse will be alluded to further on (p. 292). In these cases the rivers preceded the mountains. Indeed as soon as the land rose above the waters, rivers would begin their work, and having done so, unless the rate of elevation of the mountain exceeded the power of erosion of the river, the two would proceed simultaneously, so that the river would not alter its course, but would cut deeper and deeper as the mountain range gradually rose.

Rivers then are in many cases older than mountains. Moreover, the mountains are passive, the rivers active. Since it seems to be well established that in Switzerland a mass, more than equal to what remains, has been removed; and that many of the present mountains are not sites which were originally raised highest, but those which have suffered least, it follows that if in some cases the course of the river is due to the direction of the mountain ridges, on the other hand the direction of some of the present ridges is due to that of the rivers. At any rate it is certain that of the original surface not a trace or a fragment remains in situ. Many of our own English mountains were once valleys, and many of our present valleys occupy the sites of former mountain ridges.

Heim and Ruetimeyer point out that of the two factors which have produced the relief of mountain regions, the one, elevation, is temporary and transitory; the other, denudation, is constant, and gains therefore finally the upper hand.

We must not, however, expect too great regularity. The degree of hardness, the texture, and the composition of the rocks cause great differences.

On the other hand, if the alteration of level was too rapid, the result might be greatly to alter the river courses. Mr. Darwin mentions such a case, which, moreover, is perhaps the more interesting as being evidently very recent.

"Mr. Gill," he says, "mentioned to me a most interesting, and as far as I am aware, quite unparalleled case, of a subterranean disturbance having changed the drainage of a country. Travelling from Casma to Huaraz (not very far distant from Lima) he found a plain covered with ruins and marks of ancient cultivation, but now quite barren. Near it was the dry course of a considerable river, whence the water for irrigation had formerly been conducted. There was nothing in the appearance of the water-course to indicate that the river had not flowed there a few years previously; in some parts beds of sand and gravel were spread out; in others, the solid rock had been worn into a broad channel, which in one spot was about 40 yards in breadth and 8 feet deep. It is self-evident that a person following up the course of a stream will always ascend at a greater or less inclination. Mr. Gill therefore, was much astonished when walking up the bed of this ancient river, to find himself suddenly going downhill. He imagined that the downward slope had a fall of about 40 or 50 feet perpendicular. We here have unequivocal evidence that a ridge had been uplifted right across the old bed of a stream. From the moment the river course was thus arched, the water must necessarily have been thrown back, and a new channel formed. From that moment also the neighbouring plain must have lost its fertilising stream, and become a desert."[52]

The strata, moreover, often—indeed generally, as we have seen, for instance, in the case of Switzerland—bear evidence of most violent contortions, and even where the convulsions were less extreme, the valleys thus resulting are sometimes complicated by the existence of older valleys formed under previous conditions.

In the Alps then the present configuration of the surface is mainly the result of denudation. If we look at a map of Switzerland we can trace but little relation between the river courses and the mountain chains.



The rivers, as a rule (Fig. 40), run either S.E. by N.W., or, at right angles to this, N.E. and S.W. The Alps themselves follow a somewhat curved line from the Maritime Alps, commencing with the islands of Hyeres, by Briancon, Martigny, the Valais, Urseren Thal, Vorder Rhein, Innsbruck, Radstadt, and Rottenmann to the Danube, a little below Vienna,—at first nearly north and south, but gradually curving round until it becomes S.W. by N.E.

The central mountains are mainly composed of Gneiss, Granite, and crystalline Schists: the line of junction between these rocks and the secondary and tertiary strata on the north, runs, speaking roughly, from Hyeres to Grenoble, and then by Albertville, Sion, Chur, Inns, bruck, Radstadt, and Hieflau, towards Vienna. It is followed (in some part of their course) by the Isere, the Rhone, the Rhine, the Inn, and the Enns. One of the great folds shortly described in the preceding chapter runs up the Isere, along the Chamouni Valley, up the Rhone, through the Urseren Thal, down the Rhine Valley to Chur, along the Inn nearly to Kufstein, and for some distance along the Enns. Thus, then, five great rivers have taken advantage of this main fold, each of them eventually breaking through into a transverse valley.

The Pusterthal in the Tyrol offers us an interesting case of what is obviously a single valley, which has, however, been slightly raised in the centre, near Toblach, so that from this point the water flows in opposite directions—the Drau eastward, and the Rienz westward. In this case the elevation is single and slight: in the main valley there are several, and they are much loftier, still we may, I think, regard that of the Isere from Chambery to Albertville, of the Rhone from Martigny to its source, of the Urseren Thal, of the Vorder Rhine from its source to Chur, of the Inn from Landeck to below Innsbruck, even perhaps of the Enns from Radstadt to Hieflau as in one sense a single valley, due to one of these longitudinal folds, but interrupted by bosses of gneiss and granite,—one culminating in Mont Blanc, and another in the St. Gotthard,—which have separated the waters of the Isere, the Rhone, the Vorder Rhine, the Inn, and the Enns. That the valley of Chamouni, the Valais, the Urseren Thal, and that of the Vorder Rhine really form part of one great fold is further shown by the presence of a belt of Jurassic strata nipped in, as it were, between the crystalline rocks.

This seems to throw light on the remarkable turns taken by the Rhone at Martigny and the Vorder Rhine at Chur, where they respectively quit the great longitudinal fold, and fall into secondary transverse valleys. The Rhone for the upper part of its course, as far as Martigny, runs in the great longitudinal fold of the Valais; at Martigny it falls into and adopts the transverse valley, which properly belongs to the Dranse; for the Dranse is probably an older river and ran in the present course even before the great fold of the Valais. This would seem to indicate that the Oberland range is not so old as the Pennine, and that its elevation was so gradual that the Dranse was able to wear away a passage as the ridge gradually rose. After leaving the Lake of Geneva the Rhone follows a course curving gradually to the south, until it reaches St. Genix, where it falls into and adopts a transverse valley which properly belongs to the little river Guiers; it subsequently joins the Ain and finally falls into the Saone. If these valleys were attributed to their older occupiers we should therefore confine the name of the Rhone to the portion of its course from the Rhone glacier to Martigny. From Martigny it occupies successively the valleys of the Dranse, Guiers, Ain, and Saone. In fact, the Saone receives the Ain, the Ain the Guiers, the Guiers the Dranse, and the Dranse the Rhone. This is not a mere question of names, but also one of antiquity. The Saone, for instance, flowed past Lyons to the Mediterranean for ages before it was joined by the Rhone. In our nomenclature, however, the Rhone has swallowed up the others. This is the more curious because of the three great rivers which unite to form the lower Rhone, namely, the Saone, the Doubs, and the Rhone itself, the Saone brings for a large part of the year the greatest volume of water, and the Doubs has the longest course. Other similar cases might be mentioned. The Aar, for instance, is a somewhat larger river than the Rhine.



But why should the rivers, after running for a certain distance in the direction of the main axis, so often break away into lateral valleys? If the elevation of a chain of mountains be due to the causes suggested in p. 214, it is evident, though, so far as I am aware, stress has not hitherto been laid upon this, that the compression and consequent folding of the strata (Fig. 41) would not be in the direction A B only, but also at right angles to it, in the direction A C, though the amount of folding might be much greater in one direction than in the other. Thus in the case of Switzerland, while the main folds run south-west by north-east, there would be others at right angles to the main axis. The complex structure of the Swiss mountains may be partly due to the coexistence of these two directions of pressure at right angles to one another. The presence of a fold so originating would often divert the river to a course more or less nearly at right angles to its original direction.

Switzerland, moreover, slopes northwards from the Alps, so that the lowest part of the great Swiss plain is that along the foot of the Jura. Hence the main drainage runs along the line from Yverdun to Neuchatel, down the Zihl to Soleure, and then along the Aar to Waldshut: the Upper Aar, the Emmen, the Wiggern, the Suhr, the Wynen, the lower Reuss, the Sihl, and the Limmat, besides several smaller streams, running approximately parallel to one another north-north-east, and at angles to the main axis of elevation, and all joining the Aar from the south, while on the north it does not receive a single contributary of any importance.

On the south side of the Alps again we have the Dora Baltea, the Sesia, the Ticino, the Olonna, the Adda, the Adige, etc., all running south-south-east from the axis of elevation to the Po.



Indeed, the general slope of Switzerland, being from the ridge of the Alps towards the north, it will be observed (Fig. 42) that almost all the large affluents of these rivers running in longitudinal valleys fall in on the south, as, for instance, those of the Isere from Albertville to Grenoble, of the Rhone from its source to Martigny, of the Vorder Rhine from its source to Chur, of the Inn from Landeck to Kufstein, of the Enns from its source to near Admont, of the Danube from its source to Vienna, and as just mentioned, of the Aar from Bern to Waldshut. Hence also, whenever the Swiss rivers running east and west break into a transverse valley, as the larger ones all do, and some more than once, they invariably, whether originally running east or westwards, turn towards the north.

But although we thus get a clue to the general structure of Switzerland, the whole question is extremely complex, and the strata have been crumpled and folded in the most complicated manner, sometimes completely reversed, so that older rocks have been folded back on younger strata, and even in some cases these folds again refolded. Moreover, the denudation by aerial action, by glaciers, frosts, and rivers has removed hundreds, or rather thousands, of feet of strata. In fact, the mountain tops are not by any means the spots which have been most elevated, but those which have been least denuded; and hence it is that so many of the peaks stand at about the same altitude.

THE CONFLICTS AND ADVENTURES OF RIVERS

Our ancestors looked upon rivers as being in some sense alive, and in fact in their "struggle for existence" they not only labour to adapt their channel to their own requirements, but in many cases enter into conflict with one another.

In the plain of Bengal, for instance, there are three great rivers, the Brahmapootra coming from the north, the Ganges from the west, and the Megna from the east, each of them with a number of tributary streams. Mr. Fergusson[53] has given us a most interesting and entertaining account of the struggles between these great rivers to occupy the fertile plain of Bengal.

The Megna, though much inferior in size to the Brahmapootra, has one great advantage. It depends mainly on the monsoon rains for its supply, while the Brahmapootra not only has a longer course to run, but relies for its floods, to a great extent, on the melting of the snow, so that, arriving later at the scene of the struggle, it finds the country already occupied by the Megna to such an extent that it has been driven nearly 70 miles northwards, and forced to find a new channel.

Under these circumstances it has attacked the territory of the Ganges, and being in flood earlier than that river, though later than the Megna, it has in its turn a great advantage.

Whatever the ultimate result may be the struggle continues vigorously. At Sooksaghur, says Fergusson, "there was a noble country house, built by Warren Hastings, about a mile from the banks of the Hoogly. When I first knew it in 1830 half the avenue of noble trees, which led from the river to the house, was gone; when I last saw it, some eight years afterwards, the river was close at hand. Since then house, stables, garden, and village are all gone, and the river was on the point of breaking through the narrow neck of high land that remained, and pouring itself into some weak-banded nullahs in the lowlands beyond: and if it had succeeded, the Hoogly would have deserted Calcutta. At this juncture the Eastern Bengal Railway Company intervened. They were carrying their works along the ridge, and they have, for the moment at least, stopped the oscillation in this direction."

This has affected many of the other tributaries of the Ganges, so that the survey made by Rennell in 1780-90 is no longer any evidence as to the present course of the rivers. They may now be anywhere else; in some cases all we can say is that they are certainly not now where they were then.

The association of the three great European rivers, the Rhine, the Rhone, and the Danube, with the past history of our race, invests them with a singular fascination, and their past history is one of much interest. They all three rise in the group of mountains between the Galenstock and the Bernardino, within a space of a few miles; on the east the waters run into the Black Sea, on the north into the German Ocean, and on the west into the Mediterranean. But it has not always been so. Their head-waters have been at one time interwoven together.

At present the waters of the Valais escape from the Lake of Geneva at the western end, and through the remarkable defile of Fort de l'Ecluse and Malpertius, which has a depth of 600 feet, and is at one place not more than 14 feet across. Moreover, at various points round the Lake of Geneva, remains of lake terraces show that the water once stood at a level much higher than the present. One of these is rather more than 250 feet[54] above the lake.

A glance at the map will show that between Lausanne and Yverdun there is a low tract of land, and the Venoge, which falls into the Lake of Geneva between Lausanne and Morges, runs within about half a mile of the Nozon, which falls into the Lake of Neuchatel at Yverdun, the two being connected by the Canal d'Entreroches, and the height of the watershed being only 76 metres (250 feet), corresponding with the above mentioned lake terrace. It is evident, therefore, that when the Lake of Geneva stood at the level of the 250 feet terrace the waters ran out, not as now at Geneva and by Lyons to the Mediterranean, but near Lausanne by Cissonay and Entreroches to Yverdun, and through the Lake of Neuchatel into the Aar and the Rhine.

But this is not the whole of the curious history. At present the Aar makes a sharp turn to the west at Waldshut, where it falls into the Rhine, but there is reason to believe that at a former period, before the Rhine had excavated its present bed, the Aar continued its course eastward to the Lake of Constance, by the valley of the Klettgau, as is indicated by the presence of gravel beds containing pebbles which have been brought, not by the Rhine from the Grisons, but by the Aar from the Bernese Oberland, showing that the river which occupied the valley was not the Rhine but the Aar. It would seem also that at an early period the Lake of Constance stood at a considerably higher level, and that the outlet was, perhaps, from Frederichshaven to Ulm, along what are now the valleys of the Schussen and the Ried, into the Danube.

Thus the head-waters of the Rhone appear to have originally run by Lausanne and the Lake of Constance into the Danube, and so to the Black Sea. Then, after the present valley was opened between Waldshut and Basle, they flowed by Basle and the present Rhine, and after joining the Thames, over the plain which now forms the German Sea into the Arctic Ocean between Scotland and Norway. Finally, after the opening of the passage at Fort de l'Ecluse, by Geneva, Lyons, and the Valley of the Saone, to the Mediterranean.

It must not, however, be supposed that these changes in river courses are confined to the lower districts. Mountain streams have also their adventures and vicissitudes, their wars and invasions. Take for instance the Upper Rhine, of which we have a very interesting account by Heim. It is formed of three main branches, the Vorder Rhine, Hinter Rhine, and the Albula. The two latter, after meeting near Thusis, unite with the Vorder Rhine at Reichenau, and run by Chur, Mayenfeld, and Sargans into the Lake of Constance at Rheineck. At some former period, however, the drainage of this district was very different, as is shown in Fig. 43.

The Vorder and Hinter Rhine united then (Fig. 43) as they do now at Reichenau, but at a much higher level, and ran to Mayenfeld, not by Chur, but by the Kunckel Pass to Sargans, and so on, not to the Lake of Constance, but to that of Zurich. The Landwasser at that time rose in the Schlappina Joch, and after receiving as tributaries the Vereina and the Sardasca, joined the Albula, as it does now at Tiefenkasten; but instead of going round to meet the Hinter Rhine near Thusis, the two together travelled parallel with, but at some distance from, the Hinter Rhine, by Heide to Chur, and so to Mayenfeld.

In the meanwhile, however, the Landquart was stealthily creeping up the valley, attacked the ridge which then united the Casanna and the Madrishorn, and gradually forcing the passage, invaded (Fig. 44) the valleys of the Schlappina, Vereina, and Sardasca, absorbed them as tributaries, and, detaching them from their allegiance to the Landwasser, annexed the whole of the upper province which had formerly belonged to that river.



The Schyn also gradually worked its way upwards from Thusis till it succeeded in sapping the Albula, and carried it down the valley to join the Vorder Rhine near Thusis. In what is now the main valley of the Rhine above Chur another stream ate its way back, and eventually tapped the main river at Reichenau, thus diverting it from the Kunckel, and carrying it round by Chur.



At Sargans a somewhat similar process was repeated, with the addition that the material brought down by the Weisstannen, or perhaps a rockfall, deflected the Rhine, just as we see in Fig. 30 that the Rhone was pushed on one side by the Borgne. The Rhone, however, had no choice, it was obliged to force, and has forced its way over the cone deposited by the Borgne. The Rhine, on the contrary, had the option of running down by Vaduz to Rheinach, and has adopted this course. The watershed between it and the Weisstannen is, however, only about 20 feet in height, and the people of Zurich watch it carefully, lest any slight change should enable the river to return to its old bed. The result of all these changes is that the rivers have changed their courses from those shown in Fig. 43 to their present beds as shown in Fig. 44.

Another interesting case is that of the Upper Engadine (Fig. 45), to which attention has been called by Bonney and Heim. The fall of the Val Bregaglia is much steeper than that of the Inn, and the Maira has carried off the head-waters of that river away into Italy. The Col was formerly perhaps as far south as Stampa: the Albegna, the Upper Maira, and the stream from the Forgno Glacier, originally belonged to the Inn, but have been captured by the Lower Maira. Their direction still indicates this; they seem as if they regretted the unwelcome change, and yearned to rejoin their old companions.



Moreover, as rivers are continually cutting back their valleys they must of course sometimes meet. In these cases when the valleys are at different levels the lower rivers have drained the upper ones, and left dry, deserted valleys. In other cases, especially in flatter districts, we have bifurcations, as, for instance, at Sargans, and several of the Italian lakes. Every one must have been struck by the peculiar bifurcation of the Lakes of Como and Lugano, while a very slight depression would connect the Lake Varese with the Maggiore, and give it also a double southern end.

ON LAKES

The problem of the origin of Lakes is by no means identical with that of Valleys. The latter are due, primarily as a rule to geological causes, but so far as their present condition is concerned, mainly to the action of rain and rivers. Flowing water, however, cannot give rise to lakes.

It is of course possible to have valleys without lakes, and in fact the latter are, now at least, exceptional. There can be no lakes if the slope of the valley is uniform. To what then are lakes due?

Professor Ramsay divides Lakes into three classes:—

1. Those due to irregular accumulations of drift, and which are generally quite shallow.

2. Those formed by moraines.

3. Those which occupy true basins scooped by glacier ice out of the solid rock.

To these must, however, I think be added at least one other great class and several minor ones, namely,—

4. Those due to inequalities of elevation or depression.

5. Lakes in craters of extinct volcanoes, for instance, Lake Avernus.

6. Those caused by subsidence due to the removal of underlying soluble rocks, such as some of the Cheshire Meres.

7. Loop lakes in deserted river courses, of which there are many along the course of the Rhine.

8. Those due to rockfalls, landslips, or lava currents, damming up the course of a river.

9. Those caused by the advance of a glacier across a lateral valley, such as the Mergelen See, or the ancient lake whose margins form the celebrated "Parallel Roads of Glen Roy."

As regards the first class we find here and there on the earth's surface districts sprinkled with innumerable shallow lakes of all sizes, down to mere pools. Such, for instance, occur in the district of Le Doubs between the Rhone and the Saone, that of La Sologne near Orleans, in parts of North America, and in Finland. Such lakes are, as a rule, quite shallow. Some geologists, Geikie, for instance, ascribe them to the fact of these regions having been covered by sheets of ice which strewed the land with irregular masses of clay, gravel, and sand, lying on a stratum impervious to water, either of hard rock such as granite or gneiss, or of clay, so that the rain cannot percolate through it, and without sufficient inclination to throw it off.

2. To Ramsay's second class of Lakes belong those formed by moraines. The materials forming moraines being, however, comparatively loose, are easily cut through by streams. There are in Switzerland many cases of valleys crossed by old moraines, but they have generally been long ago worn through by the rivers.

3. Ramsay and Tyndall attribute most of the great Swiss and Italian lakes to the action of glaciers, and regard them as rock basins. It is of course obvious that rivers cannot make basin-shaped hollows surrounded by rock on all sides. The Lake of Geneva, 1230 feet above the sea, is over 1000 feet deep; the Lake of Brienz is 1850 feet above the sea, and 2000 feet deep, so that its bottom is really below the sea level. The Italian Lakes are even more remarkable. The Lake of Como, 700 feet above the sea, is 1929 feet deep. Lago Maggiore, 685 feet above the sea, is no less than 2625 feet deep.

If the mind is at first staggered at the magnitude of the scale, we must remember that the ice which is supposed to have scooped out the valley in which the Lake of Geneva now reposes, was once at least 4000 feet thick; while the moraines were also of gigantic magnitude, that of Ivrea, for instance, being no less than 1500 feet above the river, and several miles long.

Indeed it is obvious that a glacier many hundred, or in some cases several thousand, feet in thickness, must exercise great pressure on the bed over which it travels. We see this from the striae and grooves on the solid rocks, and the fine mud which is carried down by glacial streams. The deposit of glacial rivers, the "loess" of the Rhine itself, is mainly the result of this ice-waste, and that is why it is so fine, so impalpable. That glaciers do deepen their beds seems therefore unquestionable.

Moreover, though the depth of some of these lakes is great, the true slope is very slight.

Tyndall and Ramsay do not deny that the original direction of valleys, and consequently of lakes, is due to cosmical causes and geological structure, while even those who have most strenuously opposed the theory which attributes lakes to glacial erosion do not altogether deny the action of glaciers. Favre himself admits that "it is impossible to deny that valleys, after their formation, have been swept out and perhaps enlarged by rivers and glaciers."