ICEBERGS--THEIR APPEARANCE AND FORMS--THEIR CAUSE--GLACIERS--THEIR
NATURE AND ORIGIN--ANECDOTE OF SCORESBY--RISK AMONG ICEBERGS--MCCLURE'S
EXPERIENCE.
There are not only ice-fields, ice-floes, etcetera, in the polar seas,
but there are ice-mountains, or bergs.
It was long a matter of uncertainty as to where and how those immense
mountains, that are met with occasionally at sea, were formed. We are
now in a position to tell definitely where they originate, and how they
are produced. They are not masses of frozen sea water. Their
birth-place is in the valleys of the far north, and they are formed by
the accumulation of the snows and ice of ages. This is a somewhat
general way of stating the matter; but our subsequent explanations will,
we trust, make our meaning abundantly clear.
Icebergs are found floating in great numbers in the arctic seas. They
drift southward each spring with the general body of polar ice, and
frequently travel pretty far south in the Atlantic before the heat of
the water and atmosphere united accomplishes their dissolution. They
sometimes travel as far south as Florida with the southerly current that
flows along that coast; but the warm waters of the Gulf Stream, together
with its northerly flow, form an impassable barrier between these
ice-mountains and Europe.
Icebergs assume every variety of form, and almost every size. They
sometimes resemble castles, sometimes churches with glittering spires,
and sometimes the peaked and jagged mountains of Norway. They are also
frequently seen in the form of immense misshapen and top-heavy masses.
In size they vary from one hundred to seven or eight hundred feet in
height. One iceberg, seen by Ross in Baffin's Bay, was above two miles
in length, nearly the same in width, and fifty feet high. But in
stating this, we have not given the reader any idea of its vast
proportions; for it is well known that all icebergs, or masses of ice,
have a much greater proportion of their bulk under than above water--in
other words, they sink very deep. The relative proportion that sinks
depends on the nature of the ice. Of some kinds, there is usually ten
times as much below as there is above water; of other kinds, there may
be eight or five parts below. In all cases there is much more below
than above so that a mountain of a hundred feet high--if afloat--may be
safely calculated to be a mass of ice not far short of a thousand feet
thick.
As these bergs float southward with the currents, they melt very
rapidly. The heat of the sun and the action of the waves gradually
round off the sharp angles and topple down the spires that characterised
them in the land of their birth. The process of dissolution, too, is
carried on internally; for rain and melted water on the surface
percolates through the mass, rendering it porous. As the waves cut away
the base, the centre of gravity is thrown out, and the whole berg turns
over with a terrible crash. Sometimes loud reports like cannon-shots
are heard, and the huge mountain splits asunder; while, not
unfrequently, the whole berg falls into a heap of chaotic ruins, and
floats away in a mass of smaller pieces which disappear gradually in
their parent sea.
The formation of icebergs has, as we have said, puzzled mankind for many
years. Their existence has long been known: for, even before men dared
to venture their lives in the polar regions, navigators, in crossing the
Atlantic Ocean, frequently met with these marble-like mountains; and,
what is worse, sometimes ran at full speed against them, and were sunk
with all on board. Bergs are frequently enveloped in dense fogs, caused
by the cold atmosphere by which they are surrounded condensing the
moisture of the warmer atmosphere which they encounter on their voyage
southward; hence they are exceedingly dangerous to navigation. But now
to speak of their formation.
Many of the great valleys of the far north are completely filled up with
solid ice. Observe, we do not say that they are merely covered over
with ice; they are absolutely filled up with it from top to bottom.
Those ice-masses are known by the name of glaciers; and they are found
in most of the elevated regions of the Earth,--on the Alps and the
mountains of Norway, for instance,--but they exist in greater abundance
about the poles than elsewhere.
Glaciers _never_ melt. They have existed for unknown ages, probably
since the world began; and they will, in all likelihood, continue to
exist until the world comes to an end,--at least until the present
economy of the world terminates. They began with the first fall of
snow, and as falls of snow during the long winters of the polar regions
are frequent and heavy, the accumulated masses are many feet deep,
especially in places where drifts are gathered--sometimes fifteen,
twenty, thirty, and even forty feet deep. The summer sun could not melt
such drifts entirely. New snow was added each winter, until the valleys
of the far north were filled up; and so they remain filled up to this
day.
In order to understand the nature of glaciers clearly, let us turn back
to those remote ages that rolled over this Earth long before man was
created. Let us in spirit leap back to the time when no living creature
existed, even before the great mastodon began to leave his huge
foot-prints on the sands of time.
We have reached one of the large valleys of the arctic regions. It is
solemn, grand, and still. No merry birds, no prowling creatures, are
there to disturb the universal calm. The Creator has not yet formed the
living creatures and pronounced them "very good." It is the world's
first winter. As we look upward to the sky, we observe the first white
snow-flakes falling gently to the ground. They reach it, and, for the
first time, that valley is covered with a garment of virgin snow. The
valley is upwards of two miles broad. It rises from the sea, and goes
far back into the mountains, perhaps to the extent of ten or twelve
miles. The mountains that flank it are five or six thousand feet high.
We have seen such valleys in Norway, within the arctic circle. Before
that first winter has passed, many and many a fall of snow has thickened
and pressed down that first coat; and many a furious storm has caught up
the snow from the mountain-tops and swept it into the valley, adding to
and piling up the mass, and packing it firmly down.
Spring arrives. The short but warm arctic summer bursts upon that vale,
melting the surface of the snow; and the water thus produced sinks
through the mass, converting it into a sort of thick slush--half snow,
half water,--not liquid, yet not solid; just solid enough to lie there
apparently without motion; yet just liquid enough to creep by slow,
absolutely imperceptible degrees, down the valley. The snow in all the
mountain gorges is similarly affected: it creeps (it cannot be said to
flow) out and joins that in the vale. But we cannot perceive any of the
motion of which we are writing. The mass of snow seems to be as still
and motionless as the rocks on which we stand; nay, if we choose we may
walk on its hard surface almost without leaving the slightest print of
our foot. But if we throw a large stone on the surface of the snow and
mark the spot, and return again after many days, we shall find that the
stone has descended the valley a short distance. We shall also observe
that the snow has now a variety of markings on its surface; which might
lead us to fancy, had we not known better, that it had once been a
river, which, while raging down to the sea with all its curling rapids
and whirling eddies, had been arrested in all instant by the ice-king
and frozen solid,--in fact, it has all the graceful lines and forms of
fluidity, with all the steady, motionless aspect of solidity. It really
moves, this vast body of snow; but, like the hour hand of a watch, its
motion cannot be recognised, though we should observe it with prolonged,
unflagging attention. We have called it a vast body of snow, but this
is only comparatively speaking. It will be vaster yet before we have
done with it. At present it is but a thick semi-fluid covering, lying
at the bottom of this ancient arctic vale.
The brief summer ends. Much of the winter snow has been melted and
returned to the sea; but much, very much more, is still lying deep upon
the ground. The world's second winter comes. The first frost
effectually puts a stop to all the melting and moving that we have been
describing. The snow-river no longer moves--it is arrested. The water
no longer percolates through the snow--it is frozen. The mass is no
longer semi-fluid--it is solid ice; and the first step in the process of
a glacier's formation is begun.
Thereafter this process is continued from year to year, each winter
adding _largely_ to its bulk, each summer deducting _slightly_
therefrom. The growing mass of ice ascends the mountain-sides, swallows
the rocks and shrubs and trees in its progress, until its body becomes a
thousand feet thick: the extreme summits of the mountain-peaks alone
tower above the snowy waste, and the mass at the bottom is now, by the
pressure of superincumbent masses, pure ice, hard and clear as crystal.
When the great glacier grows old it still maintains its stealthy
downward motion during every summer. It has reached the shore, and has
been pushed, like a huge white tongue, out into the sea.
"But what has all this to do with icebergs?" it may be inquired. Much,
very much. It is common enough, in commenting on a child, to speak of
the parent. The glacier is the _mother_ of the iceberg.
When, in the world's early morning, the embryo glacier reached the sea,
its thin edges were easily broken off by the waves; but as it increased
and still further encroached, these edges became thicker and thicker,
until at last a wall of pure ice, several hundred feet high, presented
its glittering front to the ocean. It was hard and massive; the sun of
summer had little effect on its frigid face, and it seemed to bid
defiance to the sea itself. But things often are not what they seem.
Each billow sapped its foundation; it soon began to overhang its base.
At length the cohesion of the mass was not sufficient to sustain its
weight. A rending, accompanied by sounds like heaven's artillery, took
place; the crystal mountain bowed its brow and fell with thunderous
crash upon the water; then, rocking slowly under the impulse of its
dread plunge, the first iceberg floated off to sea!
It is right to remark here that this explanation is, to some extent,
disputed--at least there is a difference of opinion as to the _manner_
in which the iceberg leaves its parent glacier. There is no dispute as
to its origin. This difference will be explained shortly in a quotation
from Dr Kane's work; meanwhile, in support of the present theory, let
us listen to the words of one who saw with his own eyes something
similar to what has been described. Dr Scoresby, than whom a better
man never explored the arctic seas, says:--
"In July 1818, I was particularly fortunate in witnessing one of the
grandest effects which these polar glaciers ever present. A strong
north-westerly swell, having for some hours been beating on the shore,
had loosened a number of fragments attached to the iceberg, and various
heaps of broken ice denoted recent shoots of the seaward edge. As we
advanced towards it, with a view of proceeding close to its base, I
observed a few little pieces fall from the top; and while my eye was
fixed upon the place, an immense column, probably fifty feet square, and
one hundred and fifty feet high, began to leave the parent ice at the
top, and, leaning majestically forward, with an accelerated velocity
fell, with an awful crash, into the sea.
"The water into which it plunged was converted into an appearance of
vapour or smoke, like that from a furious cannonading. The noise was
equal to that of thunder, which it nearly resembled. The column which
fell was nearly square, and in magnitude resembled a church. It broke
into thousands of pieces. This circumstance was a happy caution, for we
might inadvertently have gone to the very base of the icy cliff from
whence masses of considerable magnitude were continually breaking!"
Now, this incident suggests the probability, that, had the face of the
glacier projected into deep water, the mass which broke off might have
fallen into the sea without being broken to pieces, and might have
floated away as a berg. We confess, however, to be partial to the view
expressed by some writers, that the great glaciers continue year by year
to thrust their thick tongues out to sea, until the projecting masses
reach water sufficiently deep to float them, when they are quietly
cracked off from their parent and carried away without any fall or
plunge. The following remarks by Dr Kane will make this more clear.
Writing of the iceberg, he says:
"So far from falling into the sea, broken by its weight from the parent
glacier, 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, and so recently admitted by myself,
seems to me at variance with the regulated and progressive action of
nature. Developed by such a process, the thousands of bergs which
throng these 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
[of Greenland] 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 height of the 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 is, indeed,
characteristic of all those arctic glaciers which issue from central
reservoirs, or _mers de glace_, upon the fords or bays, and is
strikingly in contrast with the dependent or hanging glacier of the
ravines."
Elsewhere the same writer speaks of this glacier as a line of cliff,
rising in a solid glassy wall to a height of three hundred feet above
the water-level, and with an _unfathomable_ depth below it; and its
curved face, sixty miles in length, from Cape Agassiz to Cape Forbes,
vanished into unknown space at not more than a single day's rail-road
travel from the pole. The interior with which it communicated, and from
which it issued, was an unsurveyed _mer de glace_, or sea of ice, of
apparently boundless dimensions; and from one part of this great cliff
he _saw_ long lines of huge bergs floating slowly away.
Here, we think, is ice enough and of sufficient dimensions to account
for the largest bergs that were ever beheld.
It will be at once seen, then, that icebergs, though found floating in
the sea, are not necessarily of the sea. They are composed entirely of
fresh water, and arctic ships can at any time procure a plentiful supply
of good soft drinkable water from the pools that are formed in the
hollows of the bergs.
The risk of approaching icebergs in the arctic regions is not so great
as when they are found floating further south; because when in their
native regions they are comparatively tough, whereas on their southern
journeys they become more or less disintegrated--in fact, the blow of an
axe is sometimes sufficient to cause a rent, which in its turn will
induce other rents and failings asunder, so that the whole mass runs the
risk of being entirely broken up. Hence the danger of ships, in certain
circumstances, venturing to anchor to them. Nevertheless this is a
common practice--sometimes a necessity--among discovery ships and
whalers. It is a convenient practice too; for many a vessel has been
saved from absolute destruction by getting under the lee of a good sound
iceberg, where she has lain as safely, for the time being, as if in a
harbour.
When Captain McClure was endeavouring to make the north-west passage in
1851, he was saved, from what appeared to be at least very probable
destruction, by a small iceberg. On the 17th of September he writes:
"There were several heavy floes in the vicinity. One, full six miles in
length, passed at the rate of two knots, crushing everything that
impeded its progress, and grazed our starboard-bow. Fortunately there
was but young ice upon the opposite side, which yielded to the pressure;
had it otherwise occurred, the vessel must inevitably have been cut
asunder. In the afternoon we secured to a moderately-sized iceberg,
drawing eight fathoms, which appeared to offer a fair refuge, and from
which we never afterwards parted."
To this lump of ice the ship clung with the tenacity of a bosom friend,
and followed it, literally, through thick and thin! There is something
almost ludicrous, as well as striking, in McClure's account of their
connection with this bit of ice. It conveyed them to their furthest
north-east position, and back round the Princess Royal Islands--passed
the largest within five hundred yards--returned along the coast of
Prince Albert's Land--and finally froze in at latitude 70 degrees 50
minutes north, longitude 117 degrees 55 minutes west, on the 30th
September; during which circumnavigation they received many severe
"nips," and were frequently driven close to the shore, from which their
dear friend the iceberg, small though he was, kept them off.
Icebergs assume almost every conceivable form, and are seen of every
size--sometimes, also, in great numbers. Scoresby mentions one occasion
on which he was surrounded by bergs to the number of several hundreds.
Now, all this ice that we have been speaking of, besides being, in a
secondary way, a passive agent in the affairs of man (chiefly in barring
his progress northward), is one of the most potent agents in the economy
of nature. It is the means by which the world is kept cool enough for
man and beast to dwell in. The polar regions--north and south--are, as
it were, the world's refrigerators; tempering the heated air of the
south, and, in connection with the torrid zone, spreading throughout the
Earth those beneficial influences which gladden the sphere of man's
temporal existence.