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

châlets; 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 châlets, 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 châlets, 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.

[Illustration: Fig. 17.--Adapted from Ball's paper "On the Formation of

Alpine Valleys and Lakes," _Lond. and Ed. Phil. Mag._ 1863, p. 96.]

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 Neuchâtel 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 Salève is the remnant of one of these ridges.

[Illustration: Fig. 18.--Section across the Jura from Brenets to

Neuchâtel.]

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.

[Illustration: Fig. 19.--_e_, Eocene strata; _j_, Jurassic; _s_,

Crystalline rocks.]

It has been calculated that the strata between Bâle 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, Neuchâtel, 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 _névé_ 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 Blümlis Alp, and the Plate the Mer de Glace.

[Illustration: Fig. 20.--Glacier of the Blümlis Alp.]

[Illustration: THE MER DE GLACE.

_To face page 229._]

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

à Niton at Geneva and the Pierre à Bot above Neuchâtel, 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 striæ, 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 Ægischhorn.

"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

Mârjelin 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.

[Illustration: Fig. 21.--Cotopaxi.]

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, scoriæ 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.

[Illustration: Fig. 22.--Lava Stream.]

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.

[Illustration: Fig. 23.--Stromboli, viewed from the north-west, April

1874.]

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. ü. 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.

[Illustration: RYDAL WATER. _To face page 251._]

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.

[Illustration: WINDERMERE. _To face page 254._]

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 _névé_ nestled in a

shoulder of some great mountain.

Below the _névé_ 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.

[Illustration: Fig. 24.--Upper Valley of St. Gotthard.]

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 châlets 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.

[Illustration: Fig. 25.--Section of a river valley. The dotted line

shows a slope or talus of debris.]

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.

[Illustration: Fig. 26.--Valley of the Rhone, with the waterfall of

Sallenches, showing talus of debris.]

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.

[Illustration: Fig. 27.--_A_, present river valley; _B_, old river

terrace.]

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°. Then an irregular slope followed in

many places by one or more terraces, and lastly the present bed of the

river.

[Illustration: Fig. 28.--Diagram of an Alpine valley showing a river

cone. Front view.]

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.

[Illustration: Fig. 29.--Diagram of an Alpine valley, showing a river

cone. Lateral view.]

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.

[Illustration: Fig. 30.]

[Illustration: VIEW IN THE VALAIS BELOW ST. MAURICE. _To face page

266._]

[Illustration: Fig. 31.--View in the Rhone Valley, showing a lateral

cone.]

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.

[Illustration: Fig. 32.--View in the Rhone Valley, showing the slope of

a river cone.]

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.

[Illustration: Fig. 33.--Shore of the Lake of Geneva, near Vevey.]

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]

[Illustration: VIEW UP THE VALAIS FROM THE LAKE OF GENEVA. _To face page

270._]

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.

[Illustration: Fig. 34.--View in the district of the Broads, Norfolk.]

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.

[Illustration: Fig. 35.]

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.

[Illustration: Fig. 36.]

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.

[Illustration: Fig. 37.--Map of the Lake District.]

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.

[Illustration: Fig. 38.--_a_, _a_, Upper Cretaceous strata, chiefly

Chalk, forming the North and South Downs; _b_, _b_, Escarpment of Lower

Greensand, with a valley between it and the Chalk; _c_, _c_, Weald Clay,

forming plains; _d_, Hills formed of Hastings Sand and Clay. The Chalk,

etc., once spread across the country, as shown in the dotted lines.]

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.

[Illustration: Fig. 39.--Map of the Weald of Kent.]

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 Rütimeyer 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.

[Illustration: Fig. 40.--Sketch Map of the Swiss Rivers.]

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

Hyères, 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

Hyères 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 Isère, the Rhone, the Rhine, the Inn, and the Enns.

One of the great folds shortly described in the preceding chapter runs

up the Isère, 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 Isère 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 Isère, 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 Saône. 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

Saône. In fact, the Saône 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 Saône, 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 Saône, the Doubs, and the

Rhone itself, the Saône 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.

[Illustration: Fig. 41.--Diagram in illustration of Mountain structure.]

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

Neuchâtel, 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.

[Illustration: Fig. 42.]

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 Isère 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 Neuchâtel 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 Neuchâtel

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

Saône, 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.

[Illustration: Fig. 43.--River system round Chur, as it used to be.]

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.

[Illustration: Fig. 44.--River system round Chur, as it is.]

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.

[Illustration: Fig. 45.--River system of the Maloya.]

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 Saône, 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 striæ 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."

Even Ruskin admits "that a glacier may be considered as a vast

instrument of friction, a white sand-paper applied slowly but

irresistibly to all the roughness of the hill which it covers."

It is obvious that sand-paper applied "irresistibly" and long enough,

must gradually wear away and lower the surface. I cannot therefore

resist the conclusion that glaciers have taken an important part in the

formation of lakes.

The question has sometimes been discussed as if the point at issue were

whether rivers or glaciers were the most effective as excavators. But

this is not so. Those who believe that lakes are in many cases due to

glaciers might yet admit that rivers have greater power of erosion.

There is, however, an essential difference in the mode of action. Rivers

tend to regularise their beds; they drain, rather than form lakes. Their

tendency is to cut through any projections so that finally their course

assumes some such curve as that below, from the source (_a_) to its

entrance into the sea (_b_).

[Illustration: Fig. 46.--Final Slope of a River.]

Glaciers, however, have in addition a scooping power, so that if

similarly _a d b_ in Fig. 47 represent the course of a glacier, starting

at _a_ and gradually thinning out to _e_, it may scoop out the rock to

a certain extent at _d_; in that case if it subsequently retires say to

_c_, there would be a lake lying in the basin thus formed between _c_

and _e_.

[Illustration: Fig. 47.]

On the other hand I am not disposed to attribute the Swiss lakes

altogether to the action of glaciers. In the first place it does not

seem clear that they occupy true rock basins. On this point more

evidence is required. That some lakes are due to unequal changes of

level will hardly be denied. No one, for instance, as Bonney justly

observes,[55] would attribute the Dead Sea to glacial erosion.

The Alps, as we have seen, are a succession of great folds, and there is

reason to regard the central one as the oldest. If then the same process

continued, and the outer fold was still further raised, or a new one

formed, more quickly than the rivers could cut it back, they would be

dammed up, and lakes would result.

Moreover, if the formation of a mountain region be due to subsidence,

and consequent crumpling, as indicated on p. 217, so that the strata

which originally occupied the area A B C D are compressed into A' B' C'

D', it is evident, as already mentioned, that while the line of least

resistance, and, consequently, the principal folds might be in the

direction A' B', there must also be a tendency to the formation of

similar folds at right angles, or in the direction A' C'. Thus, in the

case of Switzerland, while the main folds run south-west by north-east

there would also be others at right angles, though the amount of folding

might be much greater in the one direction than in the other. To this

cause the bosses, for instance--at Martigny, the Furca, and the Ober

Alp,--which intersect the great longitudinal valley of Switzerland, are

perhaps due.

The great American lakes also are probably due to differences of

elevation. Round Lake Ontario, for instance, there is a raised beach

which at the western end of the lake is 363 feet above the sea level,

but rises towards the East and North until near Fine it reaches an

elevation of 972 feet. As this terrace must have been originally

horizontal we have here a lake barrier, due to a difference of

elevation, amounting to over 600 feet.

In the same way we get a clue to the curious cruciform shape of the Lake

of Lucerne as contrasted with the simple outline of such lakes as those

of Neuchâtel or Zurich. That of Lucerne is a complex lake. Soundings

have shown that the bottom of the Urner See is quite flat. It is in fact

the old bed of the Reuss, which originally ran, not as now by Lucerne,

but by Schwytz and through the Lake of Zug. In the same way the Alpnach

See is the old bed of the Aa, which likewise ran through the Lake of

Zug. The old river terraces of the Reuss can be traced in places between

Brunnen and Goldau. Now these terraces must have originally sloped from

the upper part downwards, from Brunnen towards Goldau. But at present

the slope is the other way, _i.e._ from Goldau towards Brunnen. From

this and other evidence we conclude that in the direction from Lucerne

towards Rapperschwyl there has been an elevation of the land, which has

dammed up the valleys and thus turned parts of the Aa and the Reuss into

lakes--the two branches of the Lake of Lucerne known as the Alpnach See

and Urner See.

During the earthquakes of 1819 while part of the Runn of Cutch, 2000

square miles in area, sunk several feet, a ridge of land, called by the

natives the Ulla-Bund or "the wall of God," thirty miles long, and in

parts sixteen miles wide, was raised across an ancient arm of the Indus,

and turned it temporarily into a lake.

In considering the great Italian lakes, which descend far below the sea

level, we must remember that the Valley of the Po is a continuation of

the Adriatic, now filled up and converted into land, by the materials

brought down from the Alps. Hence we are tempted to ask whether the

lakes may not be remains of the ancient sea which once occupied the

whole plain. Moreover just as the Seals of Lake Baikal in Siberia carry

us back to the time when that great sheet of fresh water was in

connection with the Arctic Ocean, so there is in the character of the

Fauna of the Italian lakes, and especially the presence of a Crab in the

Lake of Garda, some confirmation of such an idea. Further evidence,

however, is necessary before these interesting questions can be

definitely answered.

Lastly, some lakes and inland seas seem to be due to even greater

cosmical causes. Thus a line inclined ten degrees to the pole beginning

at Gibraltar would pass through a great chain of inland waters--the

Mediterranean, Black Sea, Caspian, Aral, Baikal, and back again through

the great American lakes.

But though many causes have contributed to the original formation and

direction of Valleys, their present condition is mainly due to the

action of water. When we contemplate such a valley, for example, as that

which is called _par excellence_ the "Valais," we can at first hardly

bring ourselves to realise this; but we can trace up valleys, from the

little water-course made by last night's rains up to the greatest

valleys of all.

These considerations, however, do not of course apply to such

depressions as those of the great oceans. These were probably formed

when the surface of the globe began to solidify, and, though with many

modifications, have maintained their main features ever since.

ON THE CONFIGURATION OF VALLEYS

The conditions thus briefly described repeat themselves in river after

river, valley after valley, and it adds, I think, very much to the

interest with which we regard them if, by studying the general causes to

which they are due, we can explain their origin, and thus to some extent

understand the story they have to tell us, and the history they record.

What, then, has that history been? The same valley may be of a very

different character, and due to very different causes, in different

parts of its course. Some valleys are due to folds (see Fig. 41) caused

by subterranean changes, but by far the greater number are, in their

present features, mainly the result of erosion. As soon as any tract of

land rose out of the sea, the rain which fell on the surface would

trickle downwards in a thousand rills, forming pools here and there (see

Fig. 37), and gradually collecting into larger and larger streams.

Wherever the slope was sufficient the water would begin cutting into the

soil and carrying it off to the sea. This action would be the same in

any case, but, of course, would differ in rapidity according to the

hardness of the ground. On the other hand, the character of the valley

would depend greatly on the character of the strata, being narrow where

they were hard and tough; broader, on the contrary, where they were

soft, so that they crumbled readily into the stream, or where they were

easily split by the weather. Gradually the stream would eat into its bed

until it reached a certain slope, the steepness of which would depend on

the volume of water. The erosive action would then cease, but the

weathering of the sides and consequent widening would continue, and the

river would wander from one part of its valley to another, spreading the

materials and forming a river plain. At length, as the rapidity still

further diminished, it would no longer have sufficient power even to

carry off the materials brought down. It would form, therefore, a cone

or delta, and instead of meandering, would tend to divide into different

branches. These three stages, we may call those of--

1. Deepening and widening;

2. Widening and levelling;

3. Filling up;

and every place in the second stage has passed through the first; every

one in the third has passed through the second.

A velocity of 6 inches per second will lift fine sand, 8 inches will

move sand as coarse as linseed, 12 inches will sweep along fine gravel,

24 inches will roll along rounded pebbles an inch diameter, and it

requires 3 feet per second at the bottom to sweep along angular stones

of the size of an egg.