THE GLACIERS.
As introductory to a description of the Arctic Glaciers, a few words on
the formation of snow seem necessary. Briefly, it may be said that snow
is the result of the crystallization of water.
The molecules and atoms of all substances, when not constrained by some
external power, build themselves up into crystals. This is true of the
metals and minerals, if, after having been melted, they are allowed
to cool gradually. Bismuth develops the process in a very impressive
manner, and when properly fused and solidified exhibits large-sized
crystals of singular beauty.
In like manner, sugar dissolved in water produces, after evaporation
has taken place, crystals of sugar-candy. The ready crystallization
of alum is known to every school-boy who has dabbled in “chemical
experiments.” Chalk dissolved and crystallized becomes Iceland spar,
and assumes a variety of fanciful and graceful shapes. The diamond is
crystallized carbon; and the crystallizing power is inherent in all our
precious stones,--sapphire, topaz, emerald, beryl, amethyst, ruby.
In the process of crystallization, it is found that the minutest
particle of matter is possessed of an attractive and a repellent pole,
and that by their natural action the form and structure of the crystal
are determined.
The attracting poles, in the solid condition of any given substance,
are firmly interlocked; but dissolve the cohesion by the application of
sufficient heat, and the poles will recede so far as to be practically
beyond each other’s range. And thus the natural tendency of the
molecules to build themselves together is neutralized.
Water, for example, as a liquid is, to all appearance, without form;
but when sufficiently cooled, its molecules are brought under the
influence of the crystallizing force, and then arrange themselves in
the most varied and beautiful shapes. When snow falls in calm air,
the icy particles present themselves in the form of six-rayed stars.
From this type there is no departure, though the appearance of the
snow-stars in other respects is infinitely varied.
It is worth pausing, as Professor Tyndall remarks, to think what
wonderful work is going on in the atmosphere during the formation and
descent of every snow-shower: what “building power” is brought into
play! and how imperfect seem the productions of human minds and hands
when compared with those produced by the forces of Nature!
We have spoken of attracting and repelling poles; but a few words of
explanation seem desirable. Every magnet possesses two such poles;
and if iron filings be scattered over a magnet, each particle becomes
also endowed with two poles. Now suppose that similar particles, devoid
of weight, and floating in the atmosphere, come together, what will
happen? Obviously, the repellent poles will retreat from each other,
while the attractive will approach, and ultimately interlock. Further:
if the particles, instead of a single pair, possess several pairs of
poles arranged at definite points over their surfaces, you can then
picture them, in obedience to their mutual attractions and repulsions,
building themselves together in masses of definite shape and structure.
[Illustration: VARIOUS FORMS OF SNOW-CRYSTALS.]
You have, then, only to imagine the aqueous particles in cold calm
air to be gifted with poles of this description, compelling the said
particles to assume certain definite aggregates, and you have before
your mind’s eye the invisible architecture which creates the visible
and beautiful crystals of the snow.
The important part played by this crystallizing force in ice as well
as snow, will be understood from the following remarks by Professor
Tyndall, who may justly be described as the most eminent living
authority on the subject:--
At any temperature below 32° F.,--that is, freezing-point,--the
movement of heat is sufficient to loosen the molecules of water from
their rigid bonds of cohesion. But at 32° the movement is so diminished
that the atoms lock themselves together, and unite in a solid. This
act of union, however, is controlled by well-known laws. To the
unintelligent eye a block of ice seems neither more interesting nor
more beautiful than a sheet of glass; but to the instructed mind the
ice is to the glass what an oratorio of Handel is to the scream of a
ballad-singer. Ice is music, glass is noise; ice represents order,
glass confusion. In the latter, the molecular forces have brought about
an inextricable intertangled network; in the former, they have woven
a rich and regular embroidery, the designs of which are infinitely
beautiful.
Let us suppose ourselves examining a block of ice. In what way shall
we get at its structure? A sunbeam, or if that be wanting, a ray of
electric light is the anatomist to which we must confide the work of
dissection. We direct this ray straight from our lamp across the plate
of transparent ice.
It shivers into pieces the icy edifice, exactly reversing the order of
its architecture.
The crystallizing force, for example, had silently and systematically
built up atom after atom; the electric ray dislocates them (so to
speak) just as silently and systematically.
We elevate the ice-block in front of the lamp, so that the light may
now pass through its substance. Compare the ray as it enters with
the ray as it makes its exit; to the eye there is no perceptible
difference, and its intensity seems scarcely diminished. But not so
with its heat. As a thermic agent, the ray was more powerful before
its entrance than it was after its emergence. A portion of its heat is
arrested, is detained in the ice, and of this portion we now proceed to
avail ourselves. What will it effect?
We place a lens in front of the ice upon the screen. Now, observe this
image (see Illustration), the beauty of which is still very far from
the real effect. Here is one star; yonder is another; and in proportion
as the action continues, the ice appears to resolve itself more and
more into stars, all of six rays, like snow-crystals, and resembling
a beautiful flower. By moving the lens in and out, we bring new stars
into sight; and while the action continues, the edge of the petals is
covered with indentations like those of the leaf of a fern. Probably,
few of our readers have any conception of the magical beauties
concealed in a block of ice! Let them remember that prodigal Nature
works in this way throughout the whole world. Every atom of the solid
crust which covers the frozen waters of the North, has been wrought
out in obedience to the law we have enunciated. Nature is always and
everywhere harmonious; and it is the mission of Science to awaken us to
an appreciation of its concords.
[Illustration: EXHIBITION OF ICE-FLOWERS BY PROJECTION.]
[Illustration: ICE-FLOWERS.]
There is another point of our experiment to which the reader’s
attention must be directed. He sees the flowers illuminated by the
ray which traverses them. But if he examines them, while turning upon
them a ray which they will reflect and send back to his own eye, he
will see in the centre of each a spot with the brightness of burnished
silver. He will be tempted to think that this spot is a bubble of
air; but, by immersing the ice in hot water, you can melt the ice all
around the spot,--and when it alone remains, you will see it diminish
and disappear without any trace of air. The spot is a vacuum. Such is
the faithfulness to herself with which Nature operates; thus, in all
her operations, does she submit to her own laws. We know that ice, in
melting, contracts; and here we arrest the contraction, as it were, in
the very act. The water of the flowers cannot fill the space occupied
by the ice which by its fusion has given birth to them; hence the
production of a vacuum, the inseparable companion of each liquid flower.
The fragment of compact ice whose elements assume such beautiful
crystalline forms is itself a crystal. This was shown by Sir David
Brewster, who employed for the purpose of analysis that modified
form of light which we call _polarised light_. It is singularly
well adapted to bring out the peculiarities of the main structure
of substances, owing to the coloured figures which it outlines on a
screen after passing through them. All crystals with an axis--such, for
instance, as Iceland spar--yield a series of brilliantly-tinted rings,
traversed by a regularly-formed cross entirely black. As ice produces
the same figures, we are justified in attributing to it the same kind
of crystallization. We must note, however, that we are referring now
to the thick ice formed on our canals and lakes. If we examined the
first film formed on the surface of the water, we should discover in
it a completely irregular crystallization, the ray of polarised light
producing only a mosaic of varied tints, distributed without any order.
But it is easy to explain the way in which this primary crust or film
is produced. Those portions of the fluid mass in contact with the air
are the first to freeze, but each molecule of ice abandons its heat to
the contiguous water, which thereby is slightly raised in temperature,
and the result is a partial congelation. The surface we are examining
then presents a network of fine needles intercrossed in every
direction, and forming a kind of delicate lace, the meshes or intervals
of which are gradually filled up. When the network is transformed into
a continuous sheet, the loss of heat is diminished more and more as
this external crust grows thicker and thicker; but the development of
the ice invariably takes place by means of long interlaced needles,
as the reader may see for himself by breaking off a portion from the
nearest pond (in winter), and examining the sectional surface.
Having said thus much in reference to the crystallization of ice and
snow, we proceed to explain the _regelation_ and _moulding of
ice_. Some years ago, Faraday astonished the scientific world by
a very curious experiment. Splitting into two parts a piece of ice,
he brought together the parts at the moment that fusion took place on
their surfaces, and they united immediately. How are we to account for
this effect, which can be produced even in hot water?
When the temperature of water rises, the surface molecules first
become liquid, then gaseous; being placed beyond the coercitive action
of the surrounding particles, they are easily set free; transported,
on the contrary, into the centre of the mass, they are brought
absolutely under the influence of this action, which induces a new
solidification,--or, to use the scientific term, a _regelation_.
In this way it becomes easy to understand how very various forms can be
communicated by simple pressure to a fragment of ice. If the observer
successively places a straight bar in moulds of increasing curvature,
he may easily compel it to assume the shape of a ring or even of a
knot. In each mould, it is true, the ice breaks; but if the pressure is
kept up, the surfaces of the fragments are brought into contact, and
adhere so as to re-establish a condition of continuity. A snowball may
thus be converted into a sphere of ice, and the sphere, by constant
pressure, into a cup or a statue.
Professor Tyndall refers to a remarkable instance of regelation which
he observed one day in early spring. A layer of snow, not quite two
inches thick, had fallen on the glass roof of a small conservatory, and
the internal air, warming the panes, had melted the snow so far as it
was in immediate contact with them. The entire layer had slipped down
the pane, and projected beyond the edge of the roof, without falling,
and had bent and curved as required, just like a flexible body.
[Illustration: MOULDING ICE.]
The snow-fields which overspread the upper part of every glacier,
whether in the Arctic Regions or elsewhere, are composed of
crystallized snow, whose fragile, delicate, and fairy-like architecture
endures so long as it remains dry, but undergoes a great transformation
when the sun, melting the upper stratum, allows the water to
interpenetrate its substance. The fluid, congealing anew during the
night, transforms the snow into the condition technically known as
_névé_; a term given by the Swiss physicists to a granular mass
composed of small rounded icicles, disaggregated, but more adhesive
than snow-flakes, and of a density intermediate between that of snow
and that of ice. Under the pressure of new layers, and as a result of
infiltrations of water, the _névé_ unites, and solders into ice of
constantly increasing compactness.
But glacier-ice presents some other curious peculiarities. Every
abundant snow-fall on the summit of the mountains forms a layer easily
distinguishable from preceding layers--which, in most cases, have
already passed into the _névé_ condition. This stratification
becomes more apparent when the whiteness of the surface has been
sullied by dirt or dust wafted on “the wings of the wind.” It is
perceptible also in ice; but here we must not confound it with another
phenomenon of which the cause is different, the _veined structure_.
In places where glaciers have been accidentally cut down in an almost
vertical direction, the section is found to exhibit a series of
parallel veins, formed by a beautiful and very transparent azure ice
in the midst of the general mass, which is of a whitish colour, and
slightly opaque.
In different glaciers, and in different parts of the same glacier,
these blue veins will vary in number and intensity of colouring. They
are specially beautiful in crevasses of recent formation, and on the
sides of channels excavated in the ice by tiny rills resulting from
superficial fusion. Not a few glaciers exhibit this remarkable veined
structure throughout their entire extent. When a vertical cutting
exposes the delicate azure network to atmospheric influences, the
softer ice melts prior to the fusion of the blue ice which then remains
in their detached leaflets. On examining these attentively, we cannot
fail to remark the absence, or, at all events, the extreme rarity, of
air-bubbles, though they are so plentiful in the coarser ice.
Professor Tyndall’s explanation of this phenomenon is as interesting as
it is ingenious. While on a visit of inspection to the slate-quarries
of Wales, he had occasion to study the _cleavage_ of the rocks
which compose them; in other words, their faculty of dividing
naturally, a property inherent in all crystals. The schistous slate
separates easily into sheets, and in traversing different quarries one
sees that all the planes of cleavage are parallel in each. From this
circumstance our men of science were at first induced to look upon
slates as the products of the stratification of different deposits.
Such an explanation, however, could not be accepted by Tyndall, when
he observed that the minute fossils embedded in them were constantly
misshapen and flattened in the direction of the plane of cleavage,
because the great modification they had undergone could not have taken
place in superimposed strata at the bottom of the primeval sea. He
concluded that these schists, therefore, must have been subjected to a
considerable pressure; and further, that this pressure must have been
exercised at right angles with the plane of separation of the different
layers.
A long series of experiments proved that many bodies, when forcibly
compressed, exhibit in their structure a very distinctly marked
lamination, and frequently veins of very great beauty.
He carefully examined iron which had passed under the steam-hammer, or
through the rolling-mill; clay and wax were subjected to the hydraulic
press. In all cases he detected signs of cleavage; and hence we are
justified in the inference that the phenomenon is invariably produced
by pressure in all bodies of irregular internal structure. Such is the
result with glacier-ice, from whose mass the air-bubbles introduced
by the snow are gradually expelled. At first of brilliant whiteness,
it assumes, in the parallel layers corresponding to the planes of
cleavage, those beautiful azure tints which characterize the veined
structure. So little has it to do with stratification, that in places
where this is apparent it has given rise to a series of horizontal
lines, while the parallel veinings, in the same masses of ice, are all
inclined at an angle of about 60°.
The tendency to cleavage in compact ice would seem to explain the
regular form of those fragments or detached pieces with which some
parts of the glaciers are covered. Usually they occur as cubes, or
as rectangular parallelopipeds. The Alpine mountaineers name them
_séracs_,--in allusion to their resemblance to certain cheeses
which bear this name, and which are manufactured in rectangular boxes.
They have been found in many parts of a really colossal size, measuring
fifty feet in length, breadth, and depth, and as regular in shape as if
they had been hewn with a chisel.
There are many interesting points connected with the formation and
constitution of glaciers which we should gladly discuss, but we are
confined by our limits to remarks of a general character, and we must
now pass on to speak of the phenomena attendant upon their motion.
No doubt, the traveller who for the first time comes in sight of one
of these huge ice-rivers, and sees the mighty mass apparently rooted
to its valley-bed, solid, unchangeable, adamantine, finds it hard to
believe that it moves onward with a certain and an unresting, though a
gradual progress. It looks like a noble river, suddenly petrified by
some overwhelming force: congealed, as it flowed, in a moment, by some
irresistible spell! Such, indeed, is the conception of the poet:--
“Ye ice-falls! ye that from the mountain’s brow
Adown enormous ravines slope amain....
Torrents, methinks, that heard a mighty voice,
And stopped at once amid their maddest plunge!
Motionless torrents! silent cataracts!”
And this conception is justified by the _aspect_ of the glacier.
Thus, of the Glacier du Géant, Professor Tyndall says:--“It stretches
smoothly for a long distance, then becomes disturbed, and then changes
to a great frozen cascade, down which the ice appears to tumble in
wild confusion. Above the cascade you see an expanse of shining snow,
occupying an area of some square miles.” But we shall see that here, as
in the world of man, appearances are deceitful, and that the glacier
well deserves to be called an ice-river, in allusion to its regular and
continuous motion.
Between the snow-fall in the higher regions of the globe, and the
quantity of snow which every summer disappears through liquefaction,
the difference is very considerable. The supply, so to speak, exceeds
the demand, and a residuum is annually left. It is only below the
perpetual snow-line that the snow created and accumulated in winter
is wholly melted in the warm season. And, therefore, if for any
considerable period the excess upon any particular mountain continued
to accumulate, immense masses of ice would gradually rise to the
extreme height in the atmosphere affected by aqueous phenomena.
Rendu, the Roman Catholic prelate, who first led the way to the
discovery of the true nature of glaciers, says, very justly,--“The
economy of the world would be soon destroyed, if at certain points
accumulations of matter prevailed. The centre of gravity of the globe
would be insensibly displaced, and the admirable regularity of its
movements would be succeeded by disorder and perturbation. If the Poles
did not send back to the Equatorial seas the waters which, reduced
into vapour, issue daily from these burning regions, to be converted
into ice in the Arctic and Antarctic Zones, ocean would be drained
dry, and life would cease, as well as water, to circulate throughout
our world. The Creator, however, in order to ensure the permanence of
His almighty work, has called into existence the vast and powerful law
of circulation, and this law the careful observer sees reproduced in
all the economy of Nature. The water circulates from the ocean into
the air, from the air it spreads over the earth, and from the earth
it passes into the seas. The rivers return from whence they came, in
order that they may issue forth anew; the air circulates around the
globe, and, as it were, upon itself, passing and repassing successively
at all the altitudes of the atmospheric column. The elements of every
organic substance circulates in changing from the solid to the liquid
or aëriform state, and in returning from the latter to the state of
solidity or organization. It is not improbable that the universal
agent which we designate under the name of fire, light, electricity,
and magnetism, has probably also a circle of _circulation_ as
extensive as the universe. Should its movements ever be known to us
more than they now are, it is probable that they would afford the
solution of a host of problems which still defy the intellect of man.
Circulation is the law of life, the method of action employed by
Providence in the administration of the universe. In the insect, as
in the plant, as in the human body, we find a circulation, or rather
several circulations,--blood, humours, elements, fire, all which enter
into the composition of the individual.”
However fanciful may be some of the amiable prelate’s speculations,
it is certain that the glaciers obey this law of circulation. The
snow-accumulations in the upper regions are to some extent reduced by
the descent of the avalanches,--that is, of masses of snow and ice
which detach themselves from the mountain-sides and dash headlong
into the valleys below, where they are rapidly melted by the warmer
atmosphere. But this would, in itself, be wholly insufficient. Another
movement, at once more efficacious and more regular, is necessary; a
movement which embraces the entire system of the ice-masses, and which
carries the glaciers below the perpetual snow-line, so that every year
they may give up a portion of their terminal extremities. The discovery
of this general progression is one of the most fertile with which, of
late years, the physics of the globe have been enriched.
Professor Tyndall rightly observes that there are numerous obvious
indications of the existence of glacier-motion, though it is too slow
to catch the eye at once. The crevasses change within certain limits
from year to year, and sometimes from month to month; and this could
not be if the ice did not move. Rocks and stones also are observed,
which have been plainly torn from the mountain-sides. Blocks seen to
fall from particular points are afterwards noticed lower down. On the
moraines rocks are found of a totally different mineralogical character
from those composing the mountains right and left; and in all such
cases strata of the same character are found bordering the glacier
higher up. Hence the conclusion that the foreign _boulders_ have
been _floated_ down by the ice. Further, the ends or “snouts”
of many glaciers act like ploughshares on the land in front of them,
overturning with irresistible energy the huts and châlets that lie in
their path. Facts like these have been long known to the inhabitants
of the High Alps, who were thus made acquainted in a vague and general
way with the motion of the glaciers. But Science cannot deal with
generalities: it requires precise and accurate information; and this
information, so far as the progression of the glaciers is concerned,
has been obtained through the patient labours of Rendu, Charpentier,
Agassiz, Desor, Vogt, Professor Forbes, Bravais, Charles Martins,
Hopkins, Professor Tyndall, Colomb, John Ball, and Schlagintweit. Their
experiments and observations have established the truth of certain
immutable principles, and proved the existence of a general law of
movement.
The accumulation of the débris hurled headlong by the mountains forms
on the glacier-surface long lines of stone and earth, which are called
_moraines_; these diverge in certain directions, according to the
circumstances we now come to explain.
The landslips which occur on the banks or edges of the glacier give
rise to the _lateral moraines_, which are enlarged and extended
daily by the twofold effect of the fall of stones and débris, and the
progressive movement which carries them along with the whole mass of
ice. Towards the centre of the great glaciers, in almost every case,
is found a _medial moraine_; the result of the encounter of the
lateral moraines of two glaciers which have united into one. These
superficial moraines participating in the movement of the glacier, each
of their blocks eventually rolls to the foot of the terminal precipice,
and thus a _frontal moraine_ is formed on the very soil of the
valley, like an embankment raised to prohibit the further advance of
the ice. And, lastly, the bed of sand, gravel, pebbles, and detritus
which is found beneath the glacier, and over which it glides, is called
the _profound moraine_.
The furrows wrought by this last-named stratum on the bottom of the
glacier-channels show the wonderful force of friction which the
glacier exercises during its descent. The depths of these furrows
depends entirely on the hardness of the débris carried down by the
glacier, and the nature of the rocks submitted to the friction. The
polish assumed by these rocks when they are sufficiently solid to
resist the thunderous march of the glacier, indicates the enormous
pressure which it exercises on the slopes of the valley through which
it forces its way. This effort, bearing principally on the side of the
rocks turned in the direction of their crests, impresses upon them
a peculiar rounded form, so like the appearance of a flock of sheep
(_moutons_) that De Saussure gave them the name of _roches
moutonnées_.
Connected with the scientific evidence of the progressive movement of
glaciers, a glacier in the Bernese Oberland will for ever be memorable.
Two branch glaciers, the Lauteraar and the Finsteraar, unite at a
promontory called the Abschwung to form the trunk-glacier of the
Unteraar, which carries a great medial moraine along its colossal back.
Here in 1827, an “intrepid and enthusiastic” Swiss professor, Hugi, of
Solothurm (or Soleure), erected a small cabin of stones for the purpose
of observations upon the glacier. The hut moved, and he took steps to
measure its motion. In three years, 1827 to 1830, it moved 330 feet
downwards. In 1836 it had descended 2354 feet; and in 1841, it had
accomplished a journey of 4712 feet. [This was at the rate of about 336
feet a year.]
In 1840, M. Agassiz, with some scientific friends, Messrs. Desor,
Vogt, and Nicolieb, established themselves under a great overhanging
slab of rock on the same moraine, and by means of side walls, and
other appliances, constructed a rough abode which, because some of
these men of science came from Neufchâtel, they named the “Hôtel des
Neuchâtelois.”
In two years after its erection, Agassiz discovered that it had moved
downwards no less a distance than 486 feet.
These and some similar measurements brought to light a very important
fact. The reader will observe that the _middle numbers_,
corresponding to the central portion of the glacier, are the
_largest_: hence it was obvious that the _centre of a glacier,
like that of a river, moves more rapidly than the sides_.
Owing to the greater central motion of a glacier, its crevasses
invariably assume a curved outline, of which the convexity advances
towards the bottom of the valley.
It has also been ascertained that the superficial part of a glacier
moves more rapidly than its base.
Again: Tyndall and Hirst, by employing instruments of great precision,
have demonstrated that the maximum of motion is not to be found exactly
in the centre, but that, according to the windings of the valley
through which the glacier flows, it moves sometimes to the right of
the centre, and sometimes to the left. Now, the progression of a river
exhibits all the characters we have just enumerated, and the truth
foreshadowed by Rendu has been confirmed in every detail. The glacier
_is_ a “river of ice.”
The reader will naturally ask, How can a substance of such apparent
rigidity as ice obey, as it _does_ obey, the same laws which
regulate the movement of fluids? I can understand, he may say, how
water flows in such and such a manner: it is a liquid, and its
molecules are deficient in the property of cohesion; but that so solid,
and firm, and unimpressible a substance as ice should be capable of
motion seems impossible. I can understand very easily that a mass of
ice, when loosened or detached from its resting-place, will glide
downwards until arrested by some adequate obstacle; but this is not
the kind of motion you are describing. According to your explanations,
every constituent portion of the glacier moves, and the central faster
than the lateral, and the surface faster than the base.
These objections were advanced by men of science when the motion of
glaciers was first put forward as a theory; and the answer given by
Scheuchzer was, that a glacier might be compared, in the summer
season, to a sponge saturated with water, which, when afterwards
congealed by the cold temperature of autumn and winter, expanded, and
produced a dilatation of the mass in every direction. Then, as it could
not recede, as it could not _reascend_ its valley-slope, the
augmentation of size would necessarily take place in its lower portion.
It is unnecessary for us to explain why this answer was unsatisfactory.
Subsequent observations, however, proved its impossibility, and
Professor Forbes then put forward his ideas of the _viscous
character_ of ice. But these, too, did not meet the conditions of
the phenomenon; and the view now adopted is that of Professor Tyndall,
who has shown that it is the result of the regelation we have already
described.
Professor Forbes enunciated his theory in words to the following
effect: “A glacier is an imperfect fluid or viscous body, which is
urged down slopes of certain inclination by the natural pressure of
its parts.” But we know the exceeding brittleness of ice, and how is
viscosity compatible with brittleness? We know, too, that crevasses and
fissures will suddenly form on a glacier, like the cracks on a pane of
glass. But if ice were viscous, and could expand, dilate, or stretch
as viscous substances do, these crevasses would be impossible. They
would gradually close up, like an indent in a mass of jelly. And yet it
cannot be denied that a glacier _does_ move like a viscous body;
the centre flowing past the sides, the top flowing over the bottom,
while the motion through a curved valley corresponds to fluid motion.
How are we to reconcile these apparently conflicting circumstances?
By Professor Tyndall’s regelation theory, which is founded on a fact
already mentioned; namely, that when two pieces of thawing ice are
brought in contact, they freeze together.
This _fact_, and its application irrespective of the _cause_
of regelation, may be thus illustrated: “Saw two slabs from a block
of ice, and bring their flat surfaces into contact; they immediately
freeze together. Two plates of ice, laid one upon the other, with
flannel round them overnight, are sometimes so firmly frozen in the
morning that they will rather break elsewhere than along their surface
of junction. If you enter one of the dripping ice-caves of Switzerland,
you have only to press for a moment a slab of ice against the roof of
the cave to cause it to freeze there and stick to the roof.
“Place a number of fragments of ice in a basin of water, and cause them
to touch each other; they freeze together where they touch. You can
form a chain of such fragments; and then, by taking hold of one end of
the chain, you can draw the whole series after it. Chains of icebergs
are sometimes formed in this way in the Arctic seas.”
From these observations we deduce the following result:--Snow consists
of small particles of ice. Now, if by pressure we squeeze out the air
entangled in thawing snow, and bring the little ice-granules into close
contact, they may be expected, as they do, to freeze together; and
should the expulsion of the air be complete, the squeezed snow will
assume the appearance of compact ice.
It is in this way that the consolidation of the snows takes place in
the Arctic as in the higher Alpine regions. The deeper layers of the
_névé_ are converted into more or less perfect ice by the pressure
of the superjacent layers; and further, they are made to assume the
shape of the valley which they fill, by the slow and continuous
pressure of its sides.
In glaciers, as Professor Tyndall points out, we have ample
illustrations of rude fracture and regelation; as, for example, in
the opening and closing of crevasses. The glacier is broken on the
cascades, and mended at their bases. When two branch glaciers lay their
sides together, the regelation is so firm that they begin immediately
to flow in the trunk glacier as in a single stream. The medial moraine
gives no indication by its slowness of motion that it is derived from
the sluggish ice of the sides of the branch glaciers.
We may sum up the regelation theory in few words. The ice of glaciers
changes its form and retains its continuity under _pressure_ which
keeps its particles together. But when subjected to _tension_,
sooner than stretch, it _breaks_, and behaves no longer as a
viscous body.
These are Professor Tyndall’s words, and the fact which they embody it
would be difficult to set forth more clearly or more concisely.
[Illustration: A POLAR GLACIER.]
Having said thus much of the structure, causes, characteristics,
and movement of glaciers, we proceed to consider some of the more
remarkable of those which are situated in the Arctic World.
The glaciers of the Polar Regions do not differ in structure or mode
of formation from those of other countries. Yet they possess some
peculiar features, and to a superficial observer might seem independent
of the physical laws we have attempted to explain. That this is not
the case has been shown by Charles Martins, who carefully studied the
glaciers of Spitzbergen on the occasion of the exploring voyage of
the _Recherche_ to that island, and has demonstrated that their
differences are but a particular case of the general phenomenon.
As special characters he points out, first, the rarity of needles and
prisms of ice, which he attributes to the slight inclination and the
uniformity of the slopes, as well as to the diminution of the solar
heat, which, even in the long summer days, does not melt the surface.
There are no rills or streams capable of hollowing out crevasses and
moulding protuberances or projections. But transversal crevasses
produced by the movement of the glaciers are numerous, and these are
often very wide and very deep.
[Illustration: GLACIER, ENGLISH BAY, SPITZBERGEN.]
In the terminal escarpment, which melts in proportion as it plunges
into the sea, immense caverns are sometimes seen; caverns so immense
that the azure-gleaming grottoes of the Arveiron and Grindelwald, so
much admired by European travellers, are but miniatures. “One day,”
says Charles Martins, “after having ascertained the temperature of the
sea off the great glacier of Bell Sound, I proposed to the sailors
who accompanied me to carry our boat into its cavern. I explained to
them the risk we should incur, being unwilling to attempt anything
without their consent. When our boat had crossed the threshold, we
found ourselves in an immense Gothic cathedral; long conical-pointed
cylinders of ice descended from the roof; the recesses seemed so many
chapels opening out of the principal nave; broad fissures divided
the walls, and the open intervals, like arches, sprang towards the
summits; azure gleams played over the icy surface, and were reflected
in the water. The sailors, like myself, were dumb with admiration.
But a too prolonged contemplation would have been dangerous; we soon
regained the narrow opening through which we had penetrated into this
winter temple, and, returning on board our vessel, preserved a discreet
silence respecting an escapade which might have been justly blamed. In
the evening, we saw from the shore our cathedral of the morning slowly
bend forwards, detach itself from the parent glacier, crash into the
waves, and reappear in a thousand blocks and fragments of ice, which
the retiring tide carried slowly out to sea.”
The Spitzbergen glaciers do not exhibit those numerous moraines which
are observed on the majority of those of Switzerland.
The mountains, not being very lofty, are buried, as it were, under
their burden of glaciers, instead of preponderating over them, and seem
with difficulty to lift their peaks out of the mass of ice and snow
surrounding them. Consequently, there are no considerable landslips
or falls of earth and stone, which, accumulating along the borders
of the glaciers, might form moraines. Martins is of opinion that the
Spitzbergen glaciers correspond to the upper part of the glaciers of
Switzerland; to so much, that is to say, as lies above the perpetual
snow-line.
Now, he says, the higher we ascend on an Alpine glacier, the more do
the lateral and medial moraines diminish in width and form, until
they taper away and finally disappear under the high _névés_ of
the amphitheatres from which the glacier issues, just as the mountain
torrents often take their rise in one or in several lakes terraced one
above the other.
[Illustration: GLACIER, BELL SOUND, SPITZBERGEN.]
For all these reasons, he adds, the medial and lateral moraines are
scarcely conspicuous on the glaciers of Spitzbergen; a number of stones
and boulders may be seen along their sides, and sometimes in their
centre, but the ice is never hidden, as in the Alps, under the mass of
débris accumulated upon it. As for the terminal moraines, they must be
sought at the bottom of the sea, since the terminal escarpment nearly
always overhangs it. Hence, the blocks of stone fall simultaneously
with the blocks of ice, and form a submarine frontal moraine, of which
the two extremities are occasionally visible upon the shore.
In a previous chapter we have alluded to the manner in which icebergs
are formed by the detachment from the seaward extremity of the glacier
of huge masses of ice, which the current carries out into the open
sea. To the description already given, we may here add that which
Charles Martins furnishes in his valuable and interesting record of
persevering scientific enterprise, “Du Spitzberg au Sahara”:--In
Spitzbergen, he says, the glacier, after a traject of more or less
considerable duration, reaches the sea. If the shore be rectilineal,
it advances no further; but, in the recess of a bay, where the shore
is curved, it continues its progression, supporting its bulk on the
sides of the bay, and advancing above the water, which it overhangs.
This is easily understood. In summer the sea-water at the bottom of
the bays is always at a temperature a little above 32°; on coming in
contact with this comparatively warm water the glacier melts, and, at
low tide, an interval is perceptible between the ice and the surface of
the water. The glacier being no longer supported, partially crumbles
and gives way; immense blocks detach themselves, fall into the sea,
disappear beneath the water, reappear revolving on their own axes, and
oscillate for a few moments until they have taken up their position of
equilibrium. The blocks thus detached from the floating masses, of all
sizes and shapes, are called icebergs.
[Illustration: STEAMER “CHARGING” AN ICEBERG, UPERNAVIK,
GREENLAND.]
Our traveller records that twice a day, in Magdalena Bay and Bell
Sound, he was an eye-witness of this partial ruin of the extremity
of the glaciers. Their fall was accompanied by a noise like that
of thunder; the swollen sea rushed upon the shore in a succession of
gigantic waves; the gulf was covered with icebergs, which, caught in
the swirl and eddy, issued out of the bay, like immense fleets, to gain
the sea beyond, or were stranded here and there at points where the
water was shallow. The icebergs seen by M. Martins were not, however,
of any surprising magnitude; he estimates their average height at
thirteen to sixteen feet. We have seen that those of Baffin Bay are
tenfold more considerable and imposing; but then, in that bay the
temperature of the sea is below 32°; the glacier does not melt when it
enters the water; it sinks to the bottom of the sea; and the portions
detached from it are all of greater height than even the submerged
part of the icebergs which drift to and fro in the bays and gulfs of
Spitzbergen.
* * * * *
We may follow up this description with some observations by Lieutenant
Bellot, the chivalrous young Frenchman who perished in one of the
expeditions despatched in search of Sir John Franklin and his
companions. He is speaking of the masses of ice his ship encountered
soon after doubling Cape Farewell, the south point of Greenland,
and he remarks, that as Baffin Bay narrows towards the south, the
icebergs, first set in motion higher up the bay by the northern gales,
necessarily tend to accumulate in the gorge thus formed, and so to
impede and block up Davis Strait, even when the higher waters are quite
free. It is only through a series of alternate movements of advance and
recession that the bergs finally pass beyond the barrier, and float out
into the Atlantic, to undergo a slow process of dissolution.
The mobility of the bergs, though necessary to navigation, forms at
the same time its peculiar danger, since a vessel is often placed
between the shore and the colossal masses driven forward by the wind,
or between these and the solid ice which as yet has not broken up. It
is useless to dwell upon the immense force possessed by masses which
are frequently several square leagues in extent, and which, once in
movement, cannot be stayed by any human resistance. A sailing-vessel
finds herself placed in conditions all the more unfavourable, because
the winds blow from the very direction which she is bound to take in
order to open up a way through the floes. Now, if the gale is violent,
it is perilous indeed to push forward in the midst of a labyrinth of
bergs, which form so many floating rocks; if a calm prevails, a ship
can move forward only by laborious hauling or towed by the boats.
The application of the screw-propeller to steam-ships has given to
them a great superiority, because they are not liable to any accident
to paddle-wheels, exposed as such must be to collision with the
floating ice. It is recorded that, on one occasion, a screw-steamer,
near Upernavik, on the coast of Greenland, actually _charged_
an iceberg, and drove right through it, as a railway-engine might
crash through a fence or hurdle. Of course, the berg was of no great
elevation; but its solid mass yielded to the immense force of the
steamship, and split into large fragments.
In the convulsions caused by furious tempests, which are far from
being so rare within the Arctic Circle as is popularly supposed, the
shape of the bergs becomes very irregular, and the configuration of
the ice-fields is constantly undergoing modification. Hence it often
happens that the voyager sees before him an open basin of water of
greater or less extent, from which he is separated only by a narrow
strip of ice. In such a case he endeavours to effect an opening, either
by driving his ship at full speed against the weakest part of the ice,
or with the help of immense saws, twenty feet in length, which are
worked with a rope and pulley placed at the top of a triangle formed
of long poles; or, finally, by exploding a mine. When the ice is not
very solid, the ship is forced into the opening, against the sides of
which it acts like a wedge. It will sometimes occur, in the course of
the operation, that the ice-fields, set in motion by the wind or the
currents, close in together, after having treacherously separated for
a moment, and the vessel is then subjected to a dangerous pressure.
Unhappy the mariner who does not foresee or sufficiently note the
warning signs of this accident, which is almost always accompanied
by fatal consequences. The ice, which nothing can check, passing
underneath the ship, capsizes it,--or, if it resists, crushes it.
* * * * *
We have alluded to the colossal bergs of Baffin Bay. These are thrown
off from the northern glaciers, and particularly from the enormous
ice-river named after Humboldt, which cumbers the declivities of the
Greenland Alps, beyond the 79th parallel. It has been a frequent
source of surprise to navigators that these mighty masses should
float in a contrary direction to that of the ice-fields which descend
with the Polar current towards the Atlantic. They reascend with such
rapidity that they shatter the so-called “ice-foot,” or belt of ice,
still adhering to the shore. Captain Maury has collected numerous
observations on this important subject, and he quotes the case of a
ship which was being laboriously hauled against the current, when an
enormous floating mountain coming up from the south steered against
it, but fortunately did not come into collision with it, and forging
ahead, very quickly disappeared. How is such an incident to be
explained? By the existence of a submarine counter-current, acting on
the lower extremity of the submerged portion of the berg, which, as
we have stated, is always seven or eight times larger than the bulk
_above_ the surface of the waves.
Our whalers, in their hazardous expeditions, often derive assistance
from these moving islands. They seek shelter under their lee when
sudden storms arise; for the huge bergs are scarcely affected by the
most violent gales. They find their shelter valuable also during
certain operations of the fishery for which rest and quiet are
necessary. Yet it is not absolutely exempt from danger. The seeming
friend may prove to be a concealed foe. The iceberg may collapse,
or be capsized; or formidable fragments, loosened from their sides
or summits, may topple headlong and threaten to overwhelm the ship
beneath: but as on these and other accidents we have already dwelt at
length, we refrain from wearying our readers with a twice-told tale.
The repetition in which, to some extent, we have indulged, was needful,
in order to show the reader in what way the dissolution of the lower
extremity of the glaciers is effected in the Arctic world.
* * * * *
In the neighbourhood of Cape Alexander, one of the headlands of Smith
Strait, Dr. Hayes met with a glacier, of which he gives an interesting
description in his narrative of an “Arctic Boat Journey,” (1854):--
It was the first, protruding into the ocean, which he had had an
opportunity of inspecting closely; and though small, compared with
other similar formations, it had nevertheless all their principal
characteristics. It presented to the sea a convex mural face, seventy
feet in height and about two miles in length, its centre projecting
into the water beyond the general line of the coast to the east and
west of it. The surface rose abruptly to the height of about two
hundred feet, and, sloping thence backward with a gentle inclination,
seemed to be connected with an extensive _mer de glace_ above.
Several fissures or crevasses, apparently of great depth, struck
vertically through its body, and extended far up into its interior;
and others, more shallow, which seemed to have been formed by the
streams of melted snow that poured in cataracts down into the sea. Dr.
Hayes remarks that he was impressed by its viscous appearance; but we
have shown that a certain amount of viscosity naturally appertains to
glacier ice.
[Illustration: FORCING A PASSAGE THROUGH THE ICE.]
Parallel with its convex face ran a succession of indistinctly marked
lines, which gave it the aspect of a semi-fluid mass moving downward
upon an inclined surface; and this idea was confirmed by its appearance
about the rocks on either side. Over these it seemed to have flowed;
and, fitting accurately into all their inequalities, it gave the effect
of a huge moving mass of partially solidified matter suddenly congealed.
* * * * *
Of still greater interest is the same adventurous explorer’s
description of the great Arctic _Mer de Glace_ which lies inland
from Rensselaer Bay, in about lat. 79° N., and long. 68° W.
Dr. Hayes and his party had set out on an expedition into the interior,
and after passing through a really picturesque landscape, enriched with
beds of moss and turf, patches of purple andromeda, and the trailing
branches of the dwarf-willow, they emerged upon a broad plain or
valley, in the heart of which reposed a frozen lake, about two miles in
length by half a mile in width. They traversed its transparent surface.
On either side of them rose rugged bluffs, that stretched off into long
lines of hills, culminating in series in a broad-topped mountain-ridge,
which, running away to right and left, was cut by a gap several miles
wide that opened directly before them. Immediately in front was a low
hill, around the base of which flowed on either side the branches
of a stream whose course they had followed. Leaving the river-bed
just above the lake, they climbed to the summit of this hillock; and
there a sight burst upon them, grand and imposing beyond the power of
words adequately to describe. From the rocky bed, only a few miles
in advance, a sloping wall of pure whiteness rose to a broad level
plain of ice, which, apparently without limits, stretched away toward
the unknown east. It was the great _mer de glace_ of the Arctic
continent.
Here then was, in reality, the counterpart of the river-systems of
other lands. From behind the granite hills the congealed drainings of
the interior water-sheds, the atmospheric precipitations of ages, were
moving in a mass, which, though solid, was plastic, moving down through
every gap in the mountains, swallowing up the rocks, filling the
valleys, submerging the hills: an onward, irresistible, crystal tide,
swelling to the ocean. The surface was intersected by numerous vertical
crevasses, some of considerable depth, which had drained off the melted
snow.
It was midnight when the explorers approached this colossal reservoir.
The sun was several degrees beneath the horizon, and afforded a faint
twilight-gleam. Stars of the second magnitude were dimly perceptible in
the cold, steel-blue Arctic heavens. When they were within about half
a mile of the icy wall, a brilliant meteor fell before them, and, by
its reflection upon the glassy surface beneath, greatly increased the
magical effect of the scene; while loud reports, like distant thunder
or the roll of artillery, broke at intervals from the depths of the
frozen sea.
On closer inspection it was found that the face of the glacier ascended
at an angle of from 30° to 35°. At its base lay a high bank of snow,
and the wanderers clambered up it about sixty feet; but beyond this
their efforts were defied by the exceeding smoothness of the ice.
The mountains, which stood on either hand like giant-warders, were
overlapped, and to some extent submerged, by the glacier. From the
face of the huge ice-river innumerable little rivulets ran down the
channels their action had gradually excavated, or gurgled from beneath
the ice; forming, on the level lands below, a sort of marsh, not twenty
yards from the icy wall. Here, in strange contrast, bloomed beds of
verdurous moss; and in these, tufts of dwarf-willows were wreathing
their tiny arms and rootlets about the feebler flower-growths; and
there, clustered together, crouching among the grass, and sheltered
by the leaves, and feeding on the bed of lichens, flourished a tiny,
white-blossomed draba and a white chickweed. Dotting the few feet of
green around might be seen the yellow flowers of the more hardy poppy,
the purple potentilla, and saxifrages yellow, purple, and white.
* * * * *
The great glacier of Sermiatsialik is one of the arms, or outlets, of
this immense reservoir of ice. It occupies the bed of a valley, varying
from three and a half to five miles in width, and attaining at certain
points a depth of upwards of three hundred and seventy feet. This
valley opens upon the fiord of Sermiatsialik, which is separated from
that of Julianshaab by the range of mountains culminating in the peak
of Redkammen.
We owe to Dr. Hayes a lively description of the Sermiatsialik glacier,
which he thinks must at some places be more than seven hundred and
fifty feet in depth, overflowing the borders of the valley like a
swollen torrent. For upwards of four leagues, the icebergs which throng
the fiord, or gulf, are those of the glacier itself, and terminating
in a wedge-like outline, disappear in the vast sea of ice expanding to
right and left above the loftiest summits, and drawing irresistibly the
eye to its rippled surface,--boundless, apparently, like that of ocean.
As the voyager sails up the gulf, he gradually loses sight of the
frozen slope, and then of the white line of the _mer de glace_:
he finds himself in front of an immense cliff, from one hundred to
two hundred feet in height, diaphanous as the purest crystals, and
reflecting all the hues of heaven.
One almost shudders as one approaches this vast domain of Winter.
Collecting in copious streams, the ice and snow melted on the surface
of the glacier pour over its brink, forming floating clouds of spray,
irradiated by rainbow colours. The din of these cascades fills the
air. At intervals, the loud reports of the internal convulsions of the
glacier are repeated by every echo.
The cliff is entirely vertical; but its face, far from being smooth,
is broken up into an infinite variety of forms: into unfathomable
cavernous hollows, symmetrical spires, ogives, pinnacles, and deep
fissures, where the eye plunges into a transparent blue, which changes
every second its fleeting, opaline tints; tints so soft, and yet so
vivid, that they defy the skill of the artist to reproduce them. The
lustre of the “dark eye of woman” is not more difficult to seize. A
deep dark green, less delicate but not less splendid, colours all the
recesses where the ice overhangs the waters. In the sunlight one sees
the surface of these huge crystals shining with the whiteness of the
purest snow; except, indeed, where recent fractures have taken place.
They suggest to the mind the idea of the gleams and reflections of
a piece of satin; the undulatory lustre and shifting sparkle being
produced by the different angles under which the light is reflected.
* * * * *
But let us suppose that we have landed; with much difficulty have
ascended the cliffs; and have clambered up the glacier to its very
summit. The scene before us, how shall we convey to the mind of the
reader?
[Illustration: THE GLACIER OF SERMIATSIALIK, GREENLAND.]
Imagine, if you can, the rapids of the Upper Niagara congealed even
to their lowest depths; imagine the falls, and the broad river, and
the great Lake Erie all frozen into solid ice; with bergs above the
cataract towering as high as the lower banks: suppose that you, the
spectator, having taken your stand upon the rapids, with the Erie so
near that you can see its crystallized surface, and you will have a
picture, on a reduced scale, of the sea of ice now spreading far before
us. The rapids will represent the glacier; the Great Fall the cliff
which it projects into the sea (only that the celebrated “horse-shoe”
is here turned outwards); the river which broadens into the Ontario
will be the fiord; and the Ontario, that dark grim ocean into which the
gigantic bergs detached from the mighty ice-cascade are slowly making
their way!
* * * * *
We must indicate, however, one remarkable dissimilarity, for which our
previous observations on the nature of glaciers will have prepared the
reader. From one bank to the other, the surface of a river is always
_horizontal_, but that of a glacier is slightly _convex_.
Through the narrow glen, or ravine, formed by this curvature of the
glacier, a kind of lateral trough or gully, bounded by the escarpment
of the soil, we reach the sea. The descent is not without its dangers,
for at every point crevasses open, separated by slippery projections.
These deep gashes, at some points, are only a few yards apart; and they
incessantly cross each other, and run into one another, so as to form a
perfect labyrinth, in the windings of which the adventurous traveller
is apt to feel bewildered.
The border of the glacier once crossed, the way becomes less difficult;
for a mile and a half the level is almost perfect, and the ice but
little broken up. The frozen desert, however, impresses us with
an almost solemn feeling, and there is something terrible in the
desolation of such a Sahara of snow!
Moreover, the traveller is irresistibly affected by the continual roar
or growling of the enormous mass, which seems to stir and shake under
our very feet. He would not be surprised if a vast chasm suddenly
yawned before him! These harsh deep voices of the glacier, however, are
not the only sounds we hear. On every side rises the murmur of brooks
which trace their furrows across the crystalline plain. Some of these
gradually converge, and, uniting, form a considerable torrent, which
leaps with a clang from icy crag to icy ledge, until it is lost in a
crevasse, or precipitated over the frozen cliff into the waters of
the fiord. The _solitude_ of the scene is complete, but not the
_silence_. The air is as full of “noises” as ever was Prospero’s
isle.
Such are the principal features of the glacier of Sermiatsialik.
* * * * *
About ninety miles north-east of Rensselaer Bay lies the great Humboldt
Glacier, which seems to serve as a connecting-link between the Old
World and the New.
It lies between the 79th and 80th parallels north, and between the 64th
and 65th meridians west, skirting the shore of Peabody Bay, which is a
bold indentation of the east coast of Kane Sea.
It was discovered in Dr. Kane’s expedition, and is probably one of the
grandest spectacles in the Arctic world. Dr. Kane acknowledges himself
unable to do justice to its magnificent aspect. He can speak only of
its “long, ever-shining line of cliff diminished to a well-pointed
wedge in the perspective;” of its “face of glistening ice, sweeping
in a long curve from the low interior, the facets in front intensely
illuminated by the sun.”
This line of cliff rises, like a solid wall of glass, three hundred
feet above the water-level, with an unknown, unfathomable depth below
it; and its curved face, _sixty miles in length_, disappears into
unknown space at not more than a single day’s railroad-travel from
the Pole. The interior with which it communicates, and from which
it issues, is an unexplored _mer de glace_, an ice-ocean, of
apparently boundless dimensions.
Such is the “mighty crystal bridge” which connects the two continents
of America and Greenland. We say, continents; for Greenland, as Dr.
Kane remarks, however insulated it may ultimately prove to be, is in
mass strictly continental. Its least possible axis, measured from Cape
Farewell to the line of the Humboldt Glacier, in the neighbourhood
of the 80th parallel, gives a length of upwards of twelve hundred
miles,--not materially less than that of Australia from its northern to
its southern cape.
Imagine the centre of such a continent, says Dr. Kane, occupied through
nearly its whole extent by a deep, unbroken sea of ice, that gathers
perennial increase from the watershed of vast snow-covered mountains
and all the precipitations of the atmosphere upon its own surface.
Imagine this, moving onward like a great glacial river, seeking outlets
at every fiord and valley, rolling icy cataracts into the Atlantic and
Greenland seas; and, having at last reached the northern limit of the
land that has borne it up, pouring out a mighty frozen torrent into
unknown Arctic space.
“It is thus,” remarks Dr. Kane, “and only thus, that we must form a
just conception of a phenomenon like this great glacier. I had looked
in my own mind for such an appearance, should I ever be fortunate
enough to reach the northern coast of Greenland. But now that it was
before me, I could hardly realize it. I had recognized, in my quiet
library at home, the beautiful analogies which Forbes and Studer have
developed between the glacier and the river; but I could not comprehend
at first this complete substitution of ice for water.
“It was slowly the conviction dawned on me that I was looking upon the
counterpart of the great river-system of Arctic Asia and America. Yet
here were no water-feeders from the south. Every particle of moisture
had its origin within the Polar Circle, and had been converted into
ice. There were no vast alluvions, no forest or animal traces borne
down by liquid torrents. Here was a plastic, moving, semi-solid mass,
obliterating life, swallowing rocks and islands, and ploughing its way
with irresistible march through the crust of an investing sea.”
* * * * *
When, at a later period, Dr. Kane made a closer examination of this
great natural wonder, he found that previously he had not realized
the full grandeur of the spectacle. He noted that the trend of the
glacier was a few degrees to the west of north; and he remarks, as the
peculiarity of its aspect, that it did not indicate _repose_, but
activity, energy, movement.
Its surface seemed to follow that of the basis-country over which
it flowed. It was undulating on and about the horizon, but as it
descended towards the sea it represented a broken plain with a general
inclination of some nine degrees, still diminishing toward the
foreground. Crevasses, which in the distance seemed like mere wrinkles,
expanded as they came nearer, and were intersected almost at right
angles by long continuous lines of fracture parallel with the face of
the glacier.
These lines, too, scarcely perceptible in the far distance, widened
as they approached the sea until they formed a gigantic stairway. It
seemed as though the ice had lost its support below, and that the mass
was let down from above in a series of steps; and such an action is
the necessary result of the heat thrown out by the soil, the excessive
surface-drainage, and the constant abrasion of the sea.
The indication of a great propelling agency seemed to be just
commencing at the time that Dr. Kane visited the great glacier. The
split-off lines of ice were evidently in motion, pressed on by those
behind, but still broadening their fissures, as if the impelling action
grew more and more energetic nearer the water, till at last they
floated away in the form of icebergs. Long files of these detached
masses might be seen, like the ranks of a stately armada, slowly
sailing out into the remote sea, their separation marked by dark
parallel shadows; broad and spacious avenues near the eye, but narrowed
in the perspective to mere furrows. A more impressive illustration of
the forces of nature it would be difficult to conceive.
Dr. Kane’s view of the formation of icebergs differs considerably from
that which most physicists entertain.
He does not believe that the berg falls into the sea, broken by its
weight from the parent glacier; he is of opinion that it _rises
from_ the sea. The process is at once gradual and comparatively
quiet. “The idea of icebergs being discharged, so universal among
systematic writers, seems to me at variance with the regulated and
progressive actions of Nature. Developed by such a process, the
thousands of bergs which throng the Polar seas should keep the air
and water in perpetual commotion, one fearful succession of explosive
detonations and propagated waves. But it is only the lesser masses
falling into deep waters which could justify the popular opinion. The
enormous masses of the great glacier are propelled, step by step and
year by year, until, reaching water capable of supporting them, they
are floated off to be lost in the temperatures of other regions.”
The Humboldt Glacier did not differ in structure from the Alpine
and Norwegian ice-growths; and its face presented nearly all the
characteristic features of the latter. The _overflow_, or viscous
overlapping of the surface, was very strongly marked. “When close to
the island rocks,” says Kane, “and looking out upon the upper table of
the glacier, I was struck with the homely analogy of the batter-cake
spreading itself out under the ladle of the housewife, the upper
surface less affected by friction, and rolling forward in consequence.”
* * * * *
The crevasses bore the marks of direct fracture, as well as of the
more gradual action of surface-drainage. The extensive watershed
between their converging planes gave to the icy surface most of the
hydrographic features of a river-system. The ice-born rivers which
divided them were margined occasionally with spires of discoloured
ice, and generally lost themselves in the central areas of the glacier
before reaching its foreground. Occasionally, too, the face of the
glacier was cut by vertical lines, which, as in the Alpine examples,
were evidently outlets for the surface drainage.
The height of this ice-wall at the nearest point was about three
hundred feet, measured from the water’s edge; and the unbroken
right line of its diminishing perspective showed that this might be
regarded as its constant measurement. It seemed, in fact, a great icy
table-land, abutting with a clean precipice against the sea. This,
indeed, is the great characteristic of all those Arctic glaciers which
issue from central reservoirs or _mers de glace_ upon the fiords
or bays, and is strikingly in contrast with the dependent or hanging
glacier of the ravines, where every line and furrow and chasm seem to
indicate the movement of descent and the mechanical disturbances which
have impeded and delayed it.
Dr. Kane named this monster glacier after Alexander Von Humboldt,
to whose labours Physical Science is so largely indebted; and the
cape which flanks it on the Greenland coast after the distinguished
naturalist, whom the world has so recently lost, Professor Agassiz.
The point at which the Humboldt Glacier enters the “Land of Washington”
affords even at a distance very clear indications of its plastic or
semi-solid character. The observer finds it impossible to resist the
impression of fluidity conveyed by its peculiar markings. Dr. Kane
very appropriately named it Cape Forbes, in honour of the illustrious
son of Scotia who contributed so largely to our true knowledge of the
structure and mode of progression of glaciers.
As the surface of the glacier, adds its discoverer, receded to the
south, its face seemed broken with piles of earth and rock-stained
rubbish, until far back in the interior it was concealed from view by
the slope of a hill. But even beyond this point its continued extension
was shown by the white glare or ice-blink in the sky above.
Its outline to the northward could not be so easily traced, on account
of the enormous discharges at its base. The talus of its descent from
the interior, looking far off to the east, ranged from 7° to 15°; so
interrupted by the crevasses, however, as only in the distance to
produce the effect of an inclined plane. A few black protuberances rose
above the glittering surface of the snow, like islands in a foamy sea.
It could be seen, from the general inequalities of its surface,
how well the huge mass adapted itself to the inequalities of the
basis-country beneath. The same modifications of hill and dale were
discernible as upon land. Thus grand and various in its imposing
aspect, it stretches to the north until it touches the new Land of
Washington, cementing together by an apparently indissoluble tie the
Greenland of the Norse Vikings and the America of the Anglo-Saxon
colonists.