THE ARCTIC SEAS.
Dangers peculiar to the Arctic Sea.--Ice-fields.--Hummocks.--
Collision of Ice-fields.--Icebergs.--Their Origin.--Their
Size.--The Glaciers which give them Birth.--Their Beauty.--
Sometimes useful Auxiliaries to the Mariner.--Dangers of anchoring
to a Berg.--A crumbling Berg.--The Ice-blink.--Fogs.--
Transparency of the Atmosphere.--Phenomena of Reflection and
Refraction.--Causes which prevent the Accumulation of Polar Ice.--
Tides.--Currents.--Ice a bad Conductor of Heat.--Wise Provisions
of Nature.
The heart of the first navigator, says Horace, must have been
shielded with threefold brass--and yet the poet knew but the sunny
Mediterranean, with its tepid floods and smiling shores: how, then,
would he have found words to express his astonishment at the intrepid
seamen who, to open new vistas to science or new roads to commerce,
first ventured to face the unknown terrors of the Arctic main?
In every part of the ocean the mariner has to guard against the perils
of hidden shoals and sunken cliffs, but the high northern waters are
doubly and trebly dangerous; for here, besides those rocks which are
firmly rooted to the ground, there are others which, freely floating
about, threaten to crush his vessel to pieces, or to force it along
with them in helpless bondage.
The Arctic navigators have given various names to these movable
shoals, which are the cause of so much delay and danger. They are
_icebergs_ when they tower to a considerable height above the waters,
and _ice-fields_ when they have a vast horizontal extension. A _floe_
is a detached portion of a field; _pack-ice_, a large area of floes
or smaller fragments closely driven together so as to oppose a firm
barrier to the progress of a ship; and _drift-ice_, loose ice in
motion, but not so firmly packed as to prevent a vessel from making her
way through its yielding masses.
[Illustration: 22. AMONG HUMMOCKS.]
The large ice-fields which the whaler encounters in Baffin’s Bay, or
on the seas between Spitzbergen and Greenland, constitute one of the
marvels of the deep. There is a solemn grandeur in the slow majestic
motion with which they are drifted by the currents to the south; and
their enormous masses, as mile after mile comes floating by, impress
the spectator with the idea of a boundless extent and an irresistible
power. But, vast and mighty as they are, they are unable to withstand
the elements combined for their destruction, and their apparently
triumphal march leads them only to their ruin.
[Illustration: 23. DRIFTING IN THE ICE.]
When they first descend from their northern strongholds, the ice of
which they are composed is of the average thickness of from ten to
fifteen feet, and their surface is sometimes tolerably smooth and even,
but in general it is covered with numberless ice-blocks or hummocks
piled upon each other in wild confusion to a height of forty or fifty
feet, the result of repeated collisions before flakes and floes were
soldered into fields. Before the end of June they are covered with
snow, sometimes six feet deep, which melting during the summer forms
small ponds or lakes upon their surface.
[Illustration: 24. FORMS OF ICEBERGS.]
Not seldom ice-fields are whirled about in rotatory motion, which
causes their circumference to gyrate with a velocity of several miles
per hour. When a field thus sweeping through the waters comes into
collision with another which may possibly be revolving with equal
rapidity in an opposite direction--when masses not seldom twenty or
thirty miles in diameter, and each weighing many millions of tons,
clash together, imagination can hardly conceive a more appalling scene.
The whalers at all times require unremitting vigilance to secure their
safety, but scarcely in any situation so much as when navigating amidst
these fields, which are more particularly dangerous in foggy weather,
as their motions can not then be distinctly observed. No wonder that
since the establishment of the fishery numbers of vessels have been
crushed to pieces between two fields in motion, for the strongest ship
ever built must needs be utterly unable to resist their power. Some
have been uplifted and thrown upon the ice; some have had their hulls
completely torn open; and others have been overrun by the ice, and
buried beneath the fragments piled upon their wreck.
[Illustration: 25. FORMS OF ICEBERGS.]
[Illustration: 26. FORMS OF ICEBERGS.]
The icebergs, which, as their name indicates, rise above the water
to a much more considerable height than the ice-fields, have a very
different origin, as they are not formed in the sea itself, but by
the glaciers of the northern highlands. As our rivers are continually
pouring their streams into the ocean, so many of the glaciers or
ice-rivers of the Arctic zone, descending to the water-edge, are slowly
but constantly forcing themselves farther and farther into the sea.
In the summer season, when the ice is particularly fragile, the force
of cohesion is often overcome by the weight of the prodigious masses
that overhang the sea or have been undermined by its waters; and in
the winter, when the air is probably 40° or 50° below zero and the sea
from 28° to 30° above, the unequal expansion of those parts of the mass
exposed to so great a difference of temperature can not fail to produce
the separation of large portions.
Most of these swimming glacier-fragments, or icebergs, which are
met with by the whaler in the Northern Atlantic, are formed on the
mountainous west coast of Greenland by the large glaciers which
discharge themselves into the fiords from Smith’s Sound to Disco Bay,
as here the sea is sufficiently deep to float them away, in spite of
the enormous magnitude they frequently attain. As they drift along
down Baffin’s Bay and Davis’s Strait, they not seldom run aground on
some shallow shore, where, bidding defiance to the short summer, they
frequently remain for many a year.
[Illustration: 27. ICEBERGS AGROUND.]
Dr. Hayes measured an immense iceberg which had stranded off the little
harbor of Tessuissak, to the north of Melville Bay. The square wall
which faced toward his base of measurement was 315 feet high, and a
fraction over three-quarters of a mile long. Being almost square-sided
above the sea, the same shape must have extended beneath it; and
since, by measurements made two days before, Hayes had discovered that
fresh-water ice floating in salt water has above the surface to below
it the proportion of one to seven, this crystallized mountain must have
gone aground in a depth of nearly half a mile. A rude estimate of its
size, made on the spot, gave in cubical contents about 27,000 millions
of feet, and in weight something like 2000 millions of tons!
Captain Ross in his first voyage mentions another of these wrecked
bergs, which was found to be 4169 yards long, 3689 yards broad, and 51
feet high above the level of the sea. It was aground in 61 fathoms,
and its weight was estimated by an officer of the “Alexander” at
1,292,397,673 tons. On ascending the flat top of this iceberg, it was
found occupied by a huge white bear, who justly deeming “discretion the
best part of valor,” sprang into the sea before he could be fired at.
The vast dimensions of the icebergs appear less astonishing when we
consider that many of the glaciers or ice-rivers from which they
are dislodged are equal in size or volume to the largest streams of
continental Europe.
Thus one of the eight glaciers existing in the district of Omenak, in
Greenland, is no less than an English mile broad, and forms an ice-wall
rising 160 feet above the sea. Further to the north, Melville Bay and
Whale Sound are the seat of vast ice-rivers. Here Tyndall glacier forms
a coast-line of ice over two miles long, almost burying its face in
the sea, and carrying the eye along a broad and winding valley, up
steps of ice of giant height, until at length the slope loses itself in
the unknown ice-desert beyond. But grand above all is the magnificent
Humboldt glacier, which, connecting Greenland and Washington Land,
forms a solid glassy wall 300 feet above the water-level, with an
unknown depth below it, while its curved face extends full sixty miles
in length from Cape Agassiz to Cape Forbes. In the temperate zone it
would be one of the mightiest rivers of the earth; here, in the frozen
solitudes of the North, it slowly drops its vast fragments into the
waters, making the solitudes around re-echo with their fall.
As the Polar shores of continental America and Siberia are generally
flat, and below the snow-line, they are consequently deprived both of
glaciers and of the huge floating masses to which these give birth.
In a high sea the waves beat against an iceberg as against a rock; and
in calm weather where there is a swell, the noise made by their rising
and falling is tremendous. Their usual form is that of a high vertical
wall, gradually sloping down to the opposite side, which is very low;
but frequently they exhibit the most fantastic shapes, particularly
after they have been a long time exposed to the corroding power of the
waves, or of warm rains pelting them from above.
A number of icebergs floating in the sea is one of the most magnificent
spectacles of nature, but the wonderful beauty of these crystal cliffs
never appears to greater advantage than when clothed by the midnight
sun with all the splendid colors of twilight.
[Illustration: 28. ICEBERGS AND GLACIER, FROBISHER BAY.]
“The bergs,” says Dr. Hayes, describing one of these enchanting nights,
“had wholly lost their chilly aspect, and glittering in the blaze of
the brilliant heavens, seemed in the distance like masses of burnished
metal or solid flame. Nearer at hand they were huge blocks of Parian
marble inlaid with mammoth gems of pearl and opal. One in particular
exhibited the perfection of the grand. Its form was not unlike that
of the Colosseum, and it lay so far away that half its height was
buried beneath the line of blood-red waters. The sun, slowly rolling
along the horizon, passed behind it, and it seemed as if the old Roman
ruins had suddenly taken fire. In the shadow of the bergs the water
was a rich green, and nothing could be more soft and tender than the
gradations of color made by the sea shoaling on the sloping tongue of
a berg close beside us. The tint increased in intensity where the ice
overhung the water, and a deep cavern near by exhibited the solid color
of the malachite mingled with the transparency of the emerald, while in
strange contrast a broad streak of cobalt blue ran diagonally through
its body. The bewitching character of the scene was heightened by a
thousand little cascades which leaped into the sea from these floating
masses, the water being discharged from lakes of melted snow and ice
which reposed in quietude far up in the valleys separating the high icy
hills of their upper surface. From other bergs large pieces were now
and then detached, plunging down into the water with deafening noise,
while the slow moving swell of the ocean resounded through their broken
archways.”
[Illustration: 29. GLACIER, BUTE INLET.]
A similar gorgeous spectacle was witnessed by Dr. Kane in Melville Bay.
The midnight sun came out over a great berg, kindling variously-colored
fires on every part of its surface, and making the ice around the ship
one great resplendency of gemwork, blazing carbuncles and rubies, and
molten gold.
In the night the icebergs are readily distinguished even at a distance
by their natural effulgence, and in foggy weather by a peculiar
blackness in the atmosphere. As they are not unfrequently drifted
by the Greenland stream considerably to the south of Newfoundland,
sometimes even as far as the fortieth or thirty-ninth degree
of latitude (May, 1841, June, 1842), ships sailing through the
north-western Atlantic require to be always on their guard against
them. The ill-fated “President,” one of our first ocean-steamers, which
was lost on its way to New York, without leaving a trace behind, is
supposed to have been sunk by a collision with an iceberg, and no doubt
many a gallant bark has either foundered in the night, or been hurled
by the storm against these floating rocks.
But though often dangerous neighbors, the bergs occasionally prove
useful auxiliaries to the mariner. From their greater bulk lying below
the water-line, they are either drifted along by the under-current
against the wind, or, from their vast dimensions, are not perceptibly
influenced even by the strongest gale, but, on the contrary, have the
appearance of moving to windward, because every other kind of ice is
drifted rapidly past them. Thus in strong adverse winds, their broad
masses, fronting the storm like bulwarks, not seldom afford protection
to ships mooring under their lee.
Anchoring to a berg is, however, not always unattended with danger,
particularly when the summer is far advanced, or in a lower latitude,
as all ice becomes exceedingly fragile when acted on by the sun or by
a temperate atmosphere. The blow of an axe then sometimes suffices to
rend an iceberg asunder, and to bury the careless seaman beneath its
ruins, or to hurl him into the yawning chasm.
[Illustration: 30. SCALING AN ICEBERG.]
Thus Scoresby relates the adventure of two sailors who were attempting
to fix an anchor to a berg. They began to hew a hole into the ice, but
scarcely had the first blow been struck, when suddenly the immense mass
split from top to bottom and fell asunder, the two halves falling in
contrary directions with a prodigious crash. One of the sailors, who
was possessed of great presence of mind, immediately scaled the huge
fragment on which he was standing, and remained rocking to and fro
on its summit until its equilibrium was restored; but his companion,
falling between the masses, would most likely have been crushed to
pieces if the current caused by their motion had not swept him within
reach of the boat that was waiting for them.
Frequently large pieces detach themselves spontaneously from an
iceberg and fall into the sea with a tremendous noise. When this
circumstance, called “calving,” takes place, the iceberg loses its
equilibrium, sometimes turns on one side, and is occasionally inverted.
Dr. Hayes witnessed the crumbling of an immense berg, resembling in
its general appearance the British House of Parliament. First one
lofty tower came tumbling into the water, starting from its surface an
immense flock of gulls; then another followed; and at length, after
five hours of rolling and crashing, there remained of this splendid
mass of congelation not a fragment that rose fifty feet above the water.
One of the most remarkable phenomena of the Polar Sea is the ice-blink,
or reflection of the ice against the sky. A stripe of light, similar
to the early dawn of morning, but without its redness, appears above
the horizon, and traces a complete aërial map of the ice to a distance
of many miles beyond the ordinary reach of vision. To the experienced
navigator the “blink” is frequently of the greatest use, as it not only
points out the vicinity of the drift-ice, but indicates its nature,
whether compact or loose, continuous or open. Thus Scoresby relates
that on the 7th of June, 1821, he saw so distinct an ice-blink, that
as far as twenty or thirty miles all round the horizon he was able to
ascertain the figure and probable extent of each ice-field. The packed
ice was distinguished from the larger fields by a more obscure and
yellow color; while each water-lane or open passage was indicated by a
deep blue stripe or patch. By this means he was enabled to find his way
out of the vast masses of ice in which he had been detained for several
days, and to emerge into the open sea.
The tendency of the pack-ice to separate in calm weather, so that one
might almost be tempted to believe in a mutual repulsive power of the
individual blocks, is likewise favorable to the Arctic navigator. The
perpetual daylight of summer is another advantage, but unfortunately
the sun is too often veiled by dense mists, which frequently obscure
the air for weeks together, particularly in July. These fogs, which
are a great impediment to the whaler’s operations, have a very
depressing influence upon the spirits; and as they are attended
with a low temperature, which even at noon does not rise much above
freezing-point, the damp cold is also physically extremely unpleasant.
At other times the sun sweeps two or three times round the pole without
being for a moment obscured by a cloud, and then the transparency of
the air is such that objects the most remote may be seen perfectly
distinct and clear. A ship’s top-gallant mast, at the distance of five
or six leagues, may be discerned when just appearing above the horizon
with a common perspective-glass, and the summits of mountains are
visible at the distance of from sixty to a hundred miles.
On such sunny days, the strong contrasts of light and shade between
the glistening snow and the dark protruding rocks produce a
remarkable deception in the apparent distance of the land, along a
steep mountainous coast. When at the distance of twenty miles from
Spitzbergen, for instance, it would be easy to induce even a judicious
stranger to undertake a passage in a boat to the shore, from a belief
that he was within a league of the land. At this distance the portions
of rock and patches of snow, as well as the contour of the different
hills, are as distinctly marked as similar objects in many other
countries, not having snow about them, would be at a fourth or a fifth
part of the distance.
Nothing can be more wonderful than the phenomena of the atmosphere
dependent on reflection and refraction, which are frequently observed
in the Arctic seas, particularly at the commencement or approach of
easterly winds. They are probably occasioned by the commixture, near
the surface of the land or sea, of two streams of air of different
temperatures, so as to occasion an irregular deposition of imperfectly
condensed vapor, which when passing the verge of the horizon apparently
raises the objects there situated to a considerable distance above it,
or extends their height beyond their natural dimensions. Ice, land,
ships, boats, and other objects, when thus enlarged and elevated, are
said to loom. The lower part of looming objects are sometimes connected
with the horizon by an apparent fibrous or columnar extension of their
parts; at other times they appear to be quite lifted into the air, a
void space being seen between them and the horizon.
A most remarkable delusion of this kind was observed by Scoresby while
sailing through the open ice, far from land. Suddenly an immense
amphitheatre inclosed by high walls of basaltic ice, so like natural
rock as to deceive one of his most experienced officers, rose around
the ship. Sometimes the refraction produced on all sides a similar
effect, but still more frequently remarkable contrasts. Single
ice-blocks expanded into architectural figures of an extraordinary
height, and sometimes the distant, deeply indented ice-border looked
like a number of towers or minarets, or like a dense forest of naked
trees. Scarcely had an object acquired a distinct form, when it began
to dissolve into another.
It is well known that similar causes produce similar effects in the
warmer regions of the earth. In the midst of the tropical ocean, the
mariner sees verdant islands rise from the waters, and in the treeless
desert fantastic palm-groves wave their fronds, as if in mockery of the
thirsty caravan.
When we consider the intense cold which reigns during the greatest part
of the year in the Arctic regions, we might naturally, expect to find
the whole of the Polar Sea covered, during the winter at least, with
one solid unbroken sheet of ice. But experience teaches us that this is
by no means the case; for the currents, the tides, the winds, and the
swell of a turbulent ocean are mighty causes of disruption, or strong
impediments to congelation. Both Lieutenant de Haven and Sir Francis
M’Clintock[1] were helplessly carried along, in the depth of winter,
by the pack-ice in Lancaster Sound and Baffin’s Bay. A berg impelled
by a strong under-current rips open an ice-field as if it were a thin
sheet of glass; and in channels, or on coasts where the tides rise to
a considerable height, their flux and reflux is continually opening
crevices and lanes in the ice which covers the waters. That even in
the highest latitudes the sea does not close except when at rest, was
fully experienced by Dr. Hayes during his wintering at Port Foulke;
for at all times, even when the temperature of the air was below the
freezing-point of mercury, he could hear from the deck of his schooner
the roar of the beating waves. From all these causes there has at no
point within the Arctic Circle been found a firm ice-belt extending,
either in winter or in summer, more than from fifty to a hundred miles
from land. And even in the narrow channels separating the islands of
the Parry Archipelago, or at the mouth of Smith Sound, the waters
will not freeze over, except when sheltered by the land, or when an
ice-pack, accumulated by long continuance of winds from one quarter,
affords the same protection.
[Illustration: 31. AN ARCTIC CHANNEL.]
But the constant motion of the Polar Sea, wherever it expands to a
considerable breadth, would be insufficient to prevent its total
congelation, if it were not assisted by other physical causes. A
magnificent system of currents is continually displacing the waters
of the ocean, and forcing the warm floods of the tropical regions to
wander to the pole, while the cold streams of the frigid zone are as
constantly migrating toward the Equator. Thus we see the Gulf Stream
flowing through the broad gateway east of Spitzbergen, and forcing out
a return current of cold water to the west of Spitzbergen, and through
Davis’s Strait.
[Illustration: 32. OPEN WATER.]
The comparatively warm floods which, in consequence of this great law
of circulation, come pouring into the Arctic seas, naturally require
some time before they are sufficiently chilled to be converted into
ice; and as sea-water has its maximum of density, or, in other words,
is heaviest a few degrees above the freezing-point of water, and then
necessarily sinks, the whole depth of the sea must of course be cooled
down to that temperature before freezing can take place. Ice being a
bad conductor of heat, likewise limits the process of congelation; for
after attaining a thickness of ten or fifteen feet, its growth is very
slow, and probably even ceases altogether; for when floating fields, or
floes, are found of a greater thickness, this increase is due to the
snow that falls upon their surface, or to the accumulation of hummocks
caused by their collision.
Thus, by the combined influence of these various physical agencies,
bounds have been set to the congelation of the Polar waters. Were it
otherwise, the Arctic lands would have been mere uninhabitable wastes;
for the existence of the seals, the walrus, and the whale depends upon
their finding some open water at every season of the year; and deprived
of this resource, all the Esquimaux, whose various tribes fringe the
coasts in the highest latitudes hitherto discovered, would perish in a
single winter.
If the Arctic glaciers did not discharge their bergs into the sea,
or if no currents conveyed the ice-floes of the north into lower
latitudes, ice would be constantly accumulating in the Polar world,
and, destroying the balance of nature, would ultimately endanger the
existence of man over the whole surface of the globe.
[Illustration: 33. GLACIER DISCHARGING.]