(with fall previously provided for it) can clear masses of that out of the way, to some purpose. There is a notable instance of this in the rock of which your correspondent speaks, under the Glacier des Bois. His idea, that the glacier is deep above and thins out below, is a curious instance of the misconception of glacier nature, from which all that Forbes has done cannot yet quite clear the public mind, nor even the geological mind. A glacier never, in a large sense, thins out at all as it expires. It flows level everywhere for its own part, and never slopes but down a slope, as a rapid in water. Pour out a pot of the thickest old white candied, but still fluent, honey you can buy, over a heap of stones, arranged as you like, to imitate rocks.1 Whatever the honey does on a small scale, the glacier does on a large; and you may thus study the glacier phenomena of current-though, of course, not those of structure or fissure -at your ease. But note this specially: When the honey is at last at rest, in whatever form it has taken, you will see it terminates in tongues with low rounded edges. The possible height of these edges, in any fluid, varies as its viscosity; it is some quarter of an inch or so in water on dry ground; the most fluent ice will stand at about a hundred feet. Next, from this outer edge of the stagnant honey, delicately skim or thin off a little at the top, and see what it will do. It will not stand in an inclined plane, but fill itself up again to a level from behind. Glacier ice does exactly the same thing; and this filling in from behind is done so subtly and delicately that, every winter, the whole glacier surface rises to replace the summer's waste, not with progressive wave, as “twice a day the Severn fills; " but with silent, level insurrection, as of ocean-tide, the gray sea-crystal passes by. And all the structural phenomena of the ice are modified by this mysterious action.

Your correspondent is also not aware that the Glacier des Bois gives a very practical and outspoken proof of its shallowness opposite the Montanvert. Very often its torrent, under wilful touch of Lucina-sceptre, leaps to the light at the top of

1 See Deucalion, vol. i. p. 93.

the rocks instead of their base.1 That fiery Arveron, sometimes, hearing from reconnoitring streamlets of a nearer way down to the valley than the rounded ice-curve under the Chapeau, fairly takes bit in teeth, and flings itself out over the brow of the rocks, and down a ravine in them, in the wildest cataract of white-thunder-clouds (endless in thunder, and with quiet fragments of rainbow for lightning), that I have ever blinded myself in the skirts of.

These bare rocks, over which the main river sometimes falls (and outlying streamlets always) are of firm-grained, massively rounded gneiss. Above them, I have no doubt, once extended the upper covering of fibrous and amianthoidal schist, which forms the greater part of the south-eastern flank of the valley of Chamouni. The schistose gneiss is continuous in direction of bed, with the harder gneiss below. But the outer portion is soft, the inner hard, and more granitic. This outer portion the descending glaciers have always stripped right off down to the hard gneiss below, and in places, as immediately above the Montanvert (and elsewhere at the brows of the valley), the beds of schistose gneiss are crushed and bent outwards in a mass (I believe) by the weight of the old glacier, for some fifty feet within their surface. This looks like work; and work of this sort when it had to be done, the glaciers were well up to, bearing down such soft masses as a strong man bends a poplar sapling; but by steady push far more than by friction. You may bend or break your sapling with bare hands, but try to rub its bark off with your

bare hands!

When once the ice, with strength always dependent on preexistent precipice, has cleared such obstacles out of its way, and made its bed to its liking, there is an end to its manifest and effectively sculptural power. I do not believe the Glacier des Bois has done more against some of the granite surfaces

1 There twice a day the Severn fills;
The salt sea-water passes by,

And hushes half the babbling Wye,
And makes a silence in the hills.

TENNYSON, "In Memoriam,” xix,

beneath it, for these four thousand years, than the drifts of desert sand have done on Sinai. Be that as it may, its power of excavation on a level is proved, as I showed in my last letter, to be zero. Your correspondent thinks the glacier power vanishes towards the extremity; but as long as the ice exists, it has the same progressive energy, and, indeed, sometimes, with the quite terminal nose of it, will plough a piece of ground scientifically enough; but it never digs a hole the stream always comes from under it full speed downhill. Now, whatever the dimensions of a glacier, if it dug a big hole, like the Lake of Geneva, when it was big, it would dig a little hole when it was little-(not that this is always safe logic, for a little stone will dig in a glacier, and a large one build; but it is safe within general limits)—which it never does, nor can, but subsides gladly into any hole prepared for it in a quite placid manner, for all its fierce looks.

I find it difficult to stop, for your correspondent, little as he thinks it, has put me on my own ground. I was forced to write upon Art by an accident (the public abuse of Turner) when I was two-and-twenty; but I had written a "Mineralogical Dictionary" as far as C, and invented a shorthand symbolism for crystalline forms, before I was fourteen and have been at stony work ever since, as I could find time, silently, not caring to speak much till the chemists had given me more help.' For, indeed, I strive, as far as may be, not to speak of anything till I know it; and in that matter of Political Economy also (though forced in like manner to write of that by unendurable circumfluent fallacy), I know my ground; and if your present correspondent, or any other, will meet me fairly, I will give them uttermost satisfaction upon any point they doubt. There is free challenge; and in the knight of Snowdoun's vows (looking first carefully to see that the rock be not a glacier boulder),

2 Following this letter in the same number of the Reader was one

ENGLISH VERSUS ALPINE GEOLOGY.

1

[From "The Reader," December 3, 1864.]

DENMARK HILL, 29th Nov. I SCARCELY know what reply to make, or whether it is necessary to reply at all, to the letter of Mr. Jukes in your last number. There is no antagonism between his views and mine, though he seems heartily to desire that there should be, and with no conceivable motive but to obtain some appearance of it suppresses the latter half of the sentence he quotes from my letter. It is true that he writes in willing ignorance of the Alps, and I in unwilling ignorance of the Wicklow hills; but the only consequent discrepancy of thought or of impression between us is, that Mr. Jukes, examining (by his own account) very old hills, which have been all but washed away to nothing, naturally, and rightly, attributes their present form, or want of form, to their prolonged ablutions, while I, examining new and lofty hills, of which, though much has been carried away, much is still left, as naturally and rightly ascribe a great part of their aspect to the modes of their elevation. The Alp-bred geologist has, however, this advantage, that (especially if he happen at spare times to have been interested in manual arts) he can hardly overlook the effects of denudation on a mountain-chain which sustains Venice on the delta of one of its torrents, and Antwerp on that of another; but the English geologist, however practised in the detection and measurement of faults filled in by cubes of fluor, may be pardoned for dimly appreciating the structure of a district in

from the well-known geologist Mr. Joseph Beete Jukes, F.R.S., who, writing from "Selly Oak, Birmingham, Nov. 22," described as "the originator of the discussion." He therefore was no doubt the author of the article in the Reader alluded to above (p. 176, note). Mr. Jukes died in 1869.

The following is the sentence from Mr. Jukes' letter alluded to: "Therefore when Mr. Ruskin says that 'the forms of the Alps are quite visibly owing to the action of elevatory, contractile, and expansive forces,' I would entreat him to listen to those who have had their vision corrected by the laborious use of chain and theodolite and protractor for many toilsome years over similar forms."

which a people strong enough to lay the foundation of the liberties of Europe in a single battle,' was educated in a fissure of the Lower Chalk.

I think, however, that, if Mr. Jukes can succeed in allaying his feverish thirst for battle, he will wish to withdraw the fourth paragraph of his letter,' and, as a general formula, even the scheme which it introduces. That scheme, sufficiently accurate as an expression of one cycle of geological action, contains little more than was known to all leading geologists five-and-twenty years ago, when I was working hard under Dr. Buckland at Oxford;' and it is so curiously unworthy of the present state of geological science, that I believe its author, in his calmer moments, will not wish to attach his name to an attempt at generalization at once so narrow, and so audacious. My experience of mountain-form is probably as much more extended than his, as my disposition to generalize respecting it is less; and, although indeed the apparent limitation of the statement which he half quotes (probably owing to his general love of denudation) from my last letter, to the chain of the Alps, was intended only to attach to the words "quite visibly," yet, had I myself expanded that state

1 The battle of Sempach (?). See the letters on The Italian Question, at the beginning of the second volume.

2 To the effect that "the form of the ground is the result wholly of denudation." For the "scheme," consisting of ten articles, see the note § below.

3 Dr. William Buckland, the geologist, and at one time Dean of Westminster. He died in 1856. See Fors Clavigera, 1873, Letter xxxiv. p.

89.

4 This and the following sentences allude to parts of the above mentioned scheme. "The whole question," wrote Mr. Jukes, "depends on the relative dates of production of the lithological composition, the petrological structure, and the form of the surface." The scheme then attempts to sketch "the order of the processes which formed these three things," in ten articles, of which the following are specially referred to by Mr. Ruskin: "1. The formation of a great series of stratified rocks on the bed of a sea. 3. The possible intrusion of great masses

of granite rock" in more or less fluent state; and 6, 7, 8, 9, which dealt with alternate elevation and depression, of which there might be “ more than one repetition,"

even