CHAPTER XI.

IMPORTANT RESULTS OF THE RECENT JOURNEY.—THE GLACIER SYSTEM OF GREENLAND.—GENERAL DISCUSSION OF THE SUBJECT.—ILLUSTRATIONS DRAWN FROM THE ALPINE GLACIERS.—GLACIER MOVEMENT.—OUTLINE OF THE GREENLANDMER DE GLACE.

The results of the journey recorded in the last chapter gave me great satisfaction. They furnished an important addition to the observations which I had made in former years; and I was glad to have an opportunity to form a more clear conception of the glacier system of Greenland. The journey possesses the greater value, that it was the first successful attempt which had been made to penetrate into the interior over themer de glace.

Although I had, in my overland journey from Van Rensselaer Harbor with Mr. Wilson, in 1853, reached the face of themer de glace, where it rested behind the lofty chain of hills which runs parallel with the axis of the continent, yet this was the first time that I had actually been upon it; and its vastness did not on the former occasion impress me as now. Even the description of the great Humboldt Glacier which I had from Mr. Bonsall, and the knowledge that I had acquired of the immense glacier discharges of the region further south, failed to inspire me with a full comprehension of the immensity of ice which lies in the valleys and upon the sides of the Greenland mountains.

Greenland may indeed be regarded as a vast reservoirof ice. Upon the slopes of its lofty hills the downy snow-flake has become the hardened crystal; and, increasing little by little from year to year and from century to century, a broad cloak of frozen vapor has at length completely overspread the land, and along its wide border there pour a thousand crystal streams into the sea.

THE GLACIER SYSTEM.

The manner of this glacier growth, beginning in some remote epoch, when Greenland, nursed in warmth and sunshine, was clothed with vegetation, is a subject of much interest to the student of physical geography. The explanation of the phenomena is, however, greatly simplified by the knowledge which various explorers have contributed from the Alps,—a quarter having all the value of the Greenland mountains, as illustrating the laws which govern the formation and movements of mountain ice, and which possesses the important advantage of greater accessibility.

It would be foreign to the scope and design of this book to enter into any general discussion of the various theories which have been put forth in explanation of the sublime phenomena, which, as witnessed in the Alpine regions, have furnished a fruitful source of widely different conclusions. It was, however, easy to perceive in the grand old bed of ice over which I had traveled, those same physical markings which had arrested the attention of Agassiz and Forbes and Tyndall, and other less illustrious explorers of Alpine glaciers; and it was a satisfaction to have confirmed by actual experiment in the field the reflections of the study. The subject had long been to me one of great interest; and I was much gratified to be able to make a comparison between the Alpine and Greenland ice.It was not difficult to read in the immense deposit over which I had walked whence came the suggestion ofdilatationto Scheuchzer, or ofslidingto De Saussure; or, in the steady progress of knowledge and discovery, the principles of action that are illustrated by the termsvitriousandviscousanddifferential motion, as applied to the Alpine ice by eminent explorers of later date.

GLACIERS.

The subject of Greenland ice is one about which there exists much popular misapprehension. As before stated, I do not here propose to enter into a minute discussion of the manner of its formation and movement, but will content myself with simply recognizing the fact, and with drawing such comparison as may be needful between the mountain ice of Greenland and similar deposits in other quarters of the world. Under this head I trust that the reader may find sufficient interest in the line of argument to follow me through a few pages, in a general review of the whole field. At a later period I will recur to some more specific details of information and discussion, as the narrative carries us to other objects of inquiry.

In order to make the subject clear, I cannot do better than to cite my illustrations from the region of the Alps, where, through a long period, earnest explorers have laboriously pursued their inquiries. One of the most important and gifted of these was M. Le Chanonie Rendu, Bishop of Annecy. This excellent and worthy man, and sincere devotee as well of science as of religion, died some seven years ago. A lifetime spent among the rugged crags and ice-cliffs of the Alpine Mountains had familiarized him with every phase of Nature in that region of sublimity and home of the wonderful. Professor Tyndall says trulyof him, that "his knowledge was extensive, his reasoning close and accurate, and his faculty of observation extraordinary;" and he early brought his splendid faculties of mind and his energy of body and profound love of truth to bear upon the elucidation of those natural phenomena which were constantly exhibited in his presence. After many years of conscientious toil, he gave to the world the results of his systematic investigations in an essay which was published in the Memoirs of the Royal Academy of Sciences of Savoy, entitled, "Théorie des Glaciers de la Savoie."

ORIGIN OF GLACIERS.

I will use the information acquired from this source as the basis of my present argument,—to demonstrate, by the law as interpreted to us from the Alps by this learned priest of Annecy, how the Arctic continent receives its cloak of crystals, and how it discharges the superabundant accumulation.

Rendu first observes the piling up of the mountain snows. The snow falling upon the mountains is partly converted into water, which runs away to the river, and through the river to the sea; and is partly converted into ice. The ice thus formed Rendu estimates to equal, in the Alps, fifty-eight inches annually,—"which would make Mont Blanc four hundred feet higher in a century, and four thousand feet higher in a thousand years."

"Now it is evident," observes he, "that nothing like this can occur in Nature."

This ice must be removed by the operation of some natural cause; and observation having shown that this actually takes place, Rendu occupies himself with methods to discover how Nature has performed the task; and he comes to this very rational conclusion:That the glacier and the river are in effect the same; that between them there is a resemblance so complete that it is impossible to find in the latter a circumstance which does not exist in the former; and as the river drains thewaterswhich fall upon the hill-sides to the ocean, so the glacier drains theicewhich forms from the snows on the mountain-sides down to the same level:

And he closes his argument with declaring the Law:—

THE LAW OF CIRCULATION.

"The conserving will of the Creator has employed for the permanence of His work the great Law ofCirculation, which, strictly examined, is found to reproduce itself in all parts of Nature."

And, in illustration of this law, we see that the waters circulate from the ocean to the air by evaporation, from the air again to the earth in the form of dews and rains and snows, and from the earth back again to the ocean through the great rivers which have gathered up the little streams from every hill-side and valley.

Now this law of Circulation is, in the icy regions of the Alps, of the lofty Himalayas, of the Andes, of the mountains of Norway and of Greenland, the same as in the lower and warmer regions of the earth, where the rivers drain the surface-water to the sea.

A glacier is in effect but a flowing stream of frozen water; and theriver systemsof the Temperate and Equatorial Zones become theglacier systemsof the Arctic and Antarctic.

We have now seen that a part of the snow which falls upon the mountains is converted into ice, and this ice, strange though it seems, is movable. By what exact principle of movement has not yet beendecided to the mutual satisfaction of the learned, but it is nevertheless true. Rendu truly remarks:—

MOVEMENT OF THE GLACIERS.

"There is a multitude of facts which would seem to necessitate the belief that the substance of glaciers enjoys a kind of ductility, which permits it to mould itself to the locality which it occupies, to grow thin, to swell and to narrow itself like a soft paste."

And this, true of the Alpine passes, is true also of the Greenland valleys. A great frozen flood is pouring down the east and west slopes of the Greenland continent; and, as in the Alps, what is gained in height by one year's freezing is lost by the downward flow of the mobile mass.

And this movement is not embarrassed by any obstacle. The lower chains of hills do not arrest it, for it moulds itself to their form, sweeps through every opening between them, or overtops them. Valleys do not interfere with its onward march, for the frozen stream enters them, and levels them with the highest hills. It heeds not the precipice, for it leaps over it into the plain below,—a giant, frozen waterfall. Winter and summer are to it alike the same. It moves ever forward in its irresistible career,—a vast, frozen tide swelling to the ocean. It pours through every outlet of the coast ranges, down every ravine and valley, overriding every impediment, grinding and crushing over the rocks; and at length it comes upon the sea. But here it does not stop. Pushing back the water, it makes its own coast line; and, moving still onward, accommodating itself to every inequality of the bed of the sea, as it had before done to the surface of the land, filling up the wide bay or fiord, expanding where it expands, narrowing where it narrows, swallowing up the islands in its slow andsteady course, it finally reaches many miles beyond the original shore-line.

And now it has attained the climax of its progress.

When, long ages ago, after pouring over the sloping land, it finally reached the coast and looked down the bay which it was ultimately to fill up, its face was many hundreds of feet high. Gradually it sank below the line of waters as it moved outward, and finally its front has almost wholly disappeared.

FORMATION OF ICEBERGS.

In a former chapter I have mentioned that a block of fresh-water ice floating in sea water rises above the surface to the extent of one eighth of its weight and bulk, while seven eighths of it are below the surface. The cause of this is too well known to need more than a passing explanation. Every school-boy is aware that water, in the act of freezing, expands, and that in the crystal condition fresh water occupies about one tenth more space than when in a fluid state; and hence, when ice floats in the fresh water from which it was formed, one tenth of it is exposed above, while the remaining nine tenths are beneath the surface. When this same fresh-water ice (which it will be remembered is the composition of the glacier) is thrown into the sea, the proportion of that above to that below being changed fromoneandninetooneandseven, is due to the greater density of the sea-water, caused by the salt which it holds in solution.

FORMATION OF ICEBERGS.

Now it will be obvious that, as the glacier continues to press further and further into the sea, the natural equilibrium of the ice must ultimately become disturbed,—that is, the end of the glacier is forced further down into the water than it would be were it free from restraint, and at liberty to float according to the properties acquired by congelation. The momentthat more than seven eighths of its front are below the water line, the glacier will, like an apple pressed down by the hand in a pail of water, have a tendency to rise, until it assumes its natural equilibrium. Now it will be remembered that the glacier is a long stream of ice, many miles in extent, and, although the end may have this tendency to rise, yet it is, for a time, held down firmly by the continuity of the whole mass. At length, however, as the end of the glacier buries itself more and more in the water, the tendency to rise becomes stronger and stronger, and finally the force thus generated is sufficient to break off a fragment, which, once free, is buoyed up to the level that is natural to it. This fragment may be a solid cube half a mile through, or even of much greater dimensions. The disruption is attended with a great disturbance of the waters, and with violent sounds which may be heard for many miles; but, floating now free in the water, the oscillations which the sudden change imparted to it gradually subside; and, after acquiring its natural equilibrium, the crystal mass drifts slowly out to sea with the current, and is called anIceberg.[6]

[6]It was formerly supposed that the icebergs were discharged by the force of gravity, but this error, as well as the true theory of berg discharge, was pointed out by Dr. H. Rink, now Royal Inspector of South Greenland. Some fragments are, however, detached from the face of the glacier and fall into the water, but these are always necessarily of comparatively small dimensions, and can scarcely be called bergs.

THE LAW OF CIRCULATION.

And thus the glacier has fulfilled its part in the great law ofCirculationand change.

The dew-drop, distilled upon the tropic palm-leaf, falling to the earth, has reappeared in the gurgling spring of the primeval forest, has flown with the rivulet to the river, and with the river to the ocean; has then vanished into the air, and, wafted northward bythe unseen wind, has fallen as a downy snow-flake upon the lofty mountain, where, penetrated by a solar ray, it has become again a little globule of water, and the chilly wind, following the sun, has converted this globule into a crystal; and the crystal takes up its wandering course again, seeking the ocean.

But where its movement was once rapid, it is now slow; where it then flowed with the river miles in an hour, it will now flow with the glacier not more in centuries; and where it once entered calmly into the sea, it will now join the world of waters in the midst of a violent convulsion.

We have thus seen that the iceberg is thedischargeof the Arctic river, that the Arctic river is the glacier, and that the glacier is the accumulation of the frozen vapors of the air. We have watched this river, moving on in its slow and steady course from the distant hills, until at length it has reached the sea; and we have seen the sea tear from the slothful stream a monstrous fragment, and take back to itself its own again. Freed from the shackles which it has borne in silence through unnumbered centuries, this new-born child of the ocean rushes with a wild bound into the arms of the parent water, where it is caressed by the surf and nursed into life again; and the crystal drops receive their long-lost freedom, and fly away on the laughing waves to catch once more the sunbeam, and to run again their course through the long cycle of the ages.

BEAUTY AND GRANDEUR OF ICEBERGS.

And thisiceberghas more significance than the great flood which the glacier's southern sister, the broad Amazon, pours into the ocean from the slopes of the Andes and the mountains of Brazil. Solemn, stately, and erect, in tempest and in calm, it rides thedeep. The restless waves resound through its broken archways and thunder against its adamantean walls. Clouds, impenetrable as those which shielded the graceful form of Arethusa, clothe it in the morning; under the bright blaze of the noonday sun it is armored in glittering silver; it robes itself in the gorgeous colors of evening; and in the silent night the heavenly orbs are mirrored in its glassy surface. Drifting snows whirl over it in the winter, and the sea-gulls swarm round it in the summer. The last rays of departing day linger upon its lofty spires; and when the long darkness is past it catches the first gleam of the returning light, and its gilded dome heralds the coming morn. The Elements combine to render tribute to its matchless beauty. Its loud voice is wafted to the shore, and the earth rolls it from crag to crag among the echoing hills. The sun steals through the veil of radiant fountains which flutter over it in the summer winds, and the rainbow on its pallid cheek betrays the warm kiss. The air crowns it with wreaths of soft vapor, and the waters around it take the hues of the emerald and the sapphire. In fulfillment of its destiny it moves steadily onward in its blue pathway, through the varying seasons and under the changeful skies. Slowly, as in ages long gone by it arose from the broad waters, so does it sink back into them. It is indeed a noble symbol of the Law,—a monument of Time's slow changes, more ancient than the Egyptian Pyramids or the obelisk of Heliopolis. Its crystals were dew-drops and snow-flakes long before the human race was born in Eden.

THE MER DE GLACE.

The glacier by which I had ascended to themer de glacefurnishes a fine illustration of growth and movement as I have described it. Coming down from themer de glacein a steadily flowing stream, it has at length filled up the entire valley in which it rests for a distance of ten miles; and its terminal face, which, as heretofore stated, is one mile across, is now two miles from the sea. The angles and measurements of October, 1860, were repeated in July, 1861, as I shall have occasion hereafter to illustrate, and the result showed the rate of progress of the glacier to be upwards of one hundred feet annually. It will thus be seen that more than a century will elapse before the front of the glacier arrives at the sea; and since six miles must be traveled over before it reaches deep water, at least five hundred years will transpire before it discharges an iceberg of any considerable magnitude. The movement of this glacier is much more rapid than others which I have explored. From "My Brother John's Glacier" the margin of themer de glacesweeps around behind the lofty hills back of Port Foulke, and comes down to the sea in a discharging glacier above Cape Alexander. This has a face of two miles, and some small icebergs are disengaged from it. Thence, after surrounding Cape Alexander, embracing it as with the arm of a mighty giant, it comes again into the water on its south side; and, continuing thence southward in a succession of broad and irregular curves, a frozen river is poured out from this great inland sea of ice through every valley of the Greenland coast from Smith's Sound to Cape Farewell, and from Cape Farewell on the Spitzbergen side northward to the remotest boundary of the explored. Northward from "My Brother John's Glacier" it makes a broad curve in the rear of the hills hitherto mentioned, and opposite Van Rensselaer Harbor it is between fifty and sixty miles from the sea, whereit was reached by Mr. Wilson and myself, as before stated. Its first appearance upon the coast in that direction is at the head of Smith's Sound, in the great Humboldt Glacier, which is reputed to be sixty miles across. Beyond this it presses upon Washington Land, and thence stretches away into the region of the unknown.

"My Brother John's Glacier," from First Camp

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