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 GREENLAND _MER 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 the
_mer de glace_.
Although I had, in my overland journey from Van Rensselaer Harbor with
Mr. Wilson, in 1853, reached the face of the _mer 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 reservoir of 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.
[Sidenote: 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
of _dilatation_ to Scheuchzer, or of _sliding_ to De Saussure; or,
in the steady progress of knowledge and discovery, the principles of
action that are illustrated by the terms _vitrious_ and _viscous_
and _differential motion_, as applied to the Alpine ice by eminent
explorers of later date.
[Sidenote: 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 truly of 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_."
[Sidenote: 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 the
_waters_ which fall upon the hill-sides to the ocean, so the glacier
drains the _ice_ which forms from the snows on the mountain-sides down
to the same level:
And he closes his argument with declaring the Law:--
[Sidenote: THE LAW OF CIRCULATION.]
"The conserving will of the Creator has employed for the permanence of
His work the great Law of _Circulation_, 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 the
_river systems_ of the Temperate and Equatorial Zones become the
_glacier systems_ of 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 been decided
to the mutual satisfaction of the learned, but it is nevertheless true.
Rendu truly remarks:--
[Sidenote: 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 and steady 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.
[Sidenote: 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 from _one_
and _nine_ to _one_ and _seven_, is due to the greater density of the
sea-water, caused by the salt which it holds in solution.
[Sidenote: 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 moment that 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
an Iceberg.[6]
[Footnote 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.]
[Sidenote: THE LAW OF CIRCULATION.]
And thus the glacier has fulfilled its part in the great law of
_Circulation_ and 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 by the
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 the _discharge_ of 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.
[Sidenote: BEAUTY AND GRANDEUR OF ICEBERGS.]
And this _iceberg_ has 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 the deep. 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.
[Sidenote: THE MER DE GLACE.]
The glacier by which I had ascended to the _mer de glace_ furnishes a
fine illustration of growth and movement as I have described it. Coming
down from the _mer de glace_ in 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
the _mer de glace_ sweeps 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, where it
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.
[Illustration]