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As I contend that many tidal waves are caused by icebergs plunging into the ocean, let us see what grounds there are for that belief. First, something causes the waves: they do not start of their own accord. If an iceberg were to plunge into the ocean, a great commotion would be raised and several large waves would be started. But how far would they run? That would depend upon many different conditions--such as the size of the wave and the force that set it moving. A pebble falling five feet will make but a small ripple, while a rock ten feet in diameter, falling one hundred feet, will make a mighty wave. Then, if no obstructions be met, and the wind be favorable, that wave would go a long way. According to Wells's "Natural Philosophy," it might get larger instead of smaller. "This wave," says he, "propagates itself into the unmoved space adjoining, continually enlarging as it goes, and forming a series of undulations." Again: "When two systems of waves, coming from different centres, meet, some curious effects are produced. If like phases in both systems coincide, or if the crest of one system coincides with the crest of the other, the new wave will be equal to the sum of the two originals."
A wave is a form, not a thing; the form advances, but not the substance of the wave. Two icebergs might frequently plunge in from different directions, and send forth just such conditions as Wells writes about. Or the one plunging in first might be farther away, and as waves move comparatively slowly, they might frequently meet at some common centre, and be increased in size and force, as he suggests.
Could anything else produce so large a wave? If not, why should we not give the greatest cause credit for the greatest effect? The wonderful ice-pressure can be produced from different causes: winds, tides, currents, and tidal waves. The tidal wave, however, makes it puzzling; for it comes when there is no wind or current, and if the tidal-wave theory were excluded it certainly would be a hard proposition to answer. If the pressure occurred only when the current changed, or the wind blew, or the tides set in or out, the question of ice-pressure would never have been wondered at. In the absence of those natural causes, it was the pressure that set people thinking and wondering how such things could be. Any close observer who reads the reports of the different explorers will have noticed how mysterious are many things in the Arctic regions. If a musk-ox were found growing fast to a rock, I doubt whether such an occurrence would excite more wonder than many things in that wonderful country, hitherto unexplained. One meets, no doubt, with many radical changes and puzzling situations--such as a change from the interior of the earth to the exterior would necessarily produce; and when one takes into account that no one knew that the earth was hollow, and supposed that whatever brought about those strange conditions was to be accounted for in a few hundred miles' journey straight north to the pole, it is not to be wondered at that people called it "the mysterious land," especially when one saw the surface of the ice, water, and land reflected in the sky and could not see a great fire. If they did see it, they called it something else--the aurora, a mock sun, a double moon, or some other wonderful phenomenon; yet nothing is mysterious when fully understood.
The perplexing situations met with in the Arctic Circle, the grand scenes of every kind, and the things difficult to understand, remind one of the man reading the dictionary: the words were fine, but he couldn't make much of the story.
It is so with the explorers: everything is grand; the ice roars, and crushes when everything is calm; the heavens are lighted up most beautifully when there is no storm; the winds blow terribly out of the clear sky: none of these things can be understood.
Nansen's second volume, page 29, of "Farthest North" describes what that famous explorer experienced from ice-pressure--caused, doubtless, by tidal waves: "To-day, about 12.30 p. m., the Fram received another violent shock, even stronger than that we had experienced during the night. There was another shake a little later. I suppose there has been a pressure aft, but could hear nothing for the storm. It is odd about this pressure; one would think that the wind was the primary cause; but it recurs pretty regularly, not-withstanding the fact that the spring tide has not yet set in; indeed, when it commenced a few days ago, it was almost a neap tide. In addition to the pressure of yesterday and last night, we had pressure on Thursday morning, at half-past nine, and again at half-past eleven. It was so strong that Peter, who was at the sounding-hole, jumped up repeatedly, thinking that the ice would burst underneath him. It is very singular, we have been quiet for so long now that we feel almost nervous when the Fram receives these shocks; everything seems to tremble as if in a violent earthquake."
Nansen's remarks about the tide having nothing to do with ice-pressure, must be accounted for in some other way. That other way is a tidal wave.
In the same volume, farther on, he says: "The ice-pressure was not noticeable after 1 o'clock on Friday night until it suddenly recommenced last night. First I heard a rumbling outside, and some snow fell down from the rigging upon the tent-roof as I sat reading; I thought it sounded like packing in the ice, and just then the Fram received a violent shock, such as she had not received last winter. I was rocked backward and forward on the chest on which I was sitting. Finding that the trembling and rumbling continued, I went out. There was a loud roar of ice, packing to the west and northwest, which continued uniformly for a couple of hours or so. * * * Just after I had come on board again, shortly before noon, the ice suddenly began to press on again. I went out to have a look; it was again in the lane on the port side; there was a strong pressure, and the ridge was gradually approaching. A little later on Sverdrup went up on deck, but soon after came below and told us that the ridge was quickly bearing down on us."
When speaking of ice-pressure, nearly all explorers speak of great ridges. Melville calls it a "frozen wave." Bernacchi says the ice was lifted seventy, eighty, and ninety feet. Nansen termed it a ridge; and all agree that they look like great ridges, or waves, that can be heard for miles in the distance before they reach the ship, and for a long time after they have passed. If the descriptions given by the several explorers do not correctly represent a set of great waves, I do not know how to describe them.
Melville describes, in expressive manner, a scene in which ice-pressure played a part during his sojourn in the Arctic regions. "It was in one of these oppressive intervals succeeding a gale," says he, "when the roar and crash of the distant masses could be distinctly heard, that the floe in which the Jeannette was imbedded began splitting in all directions. The placid and almost level surface of ice suddenly heaved and swelled into great hills, buzzing and wheezing dolefully. Giant blocks pitched and rolled as though controlled by invisible hands, and the vast compressing bodies shrieked a shrill and horrible song that curdled the blood. On came the frozen waves, nearer and nearer. Seams ran and rattled across them with a thundering boom, while silent and awe-struck we watched their terrible progress." (Page 12.)
The reader will notice that these weird doings occurred after a storm; and during it the ice, as a whole, moved along with but slight disturbance. The swell that comes after a storm has no connection with it. If a storm raises no swell after raging continuously for ten to twenty-four hours, it would take a great deal to make me believe that after it had subsided it had anything to do with the swell that came later. Melville's description, just cited, proves to my mind that the whole affair arose from a series of tidal waves. The later storm had nothing to do with what he calls "frozen waves." They were caused by some tremendous agency, and I can conceive of nothing more powerful than the plunging of an iceberg into the ocean. Anyone knows that when an iceberg plunges into the sea it causes the greatest commotion imaginable, and as the tremendous swells referred to are constantly experienced, why should not the icebergs produce them? If, at a certain point on a river, laborers are engaged in rolling saw logs into the water from a high bank,--causing heavy swells to wash up against the opposite shore,--would it be a stretch of the imagination to say--if asked what caused the swells--that men were rolling logs into the water on the other side? On the contrary, it would be rather stupid on the part of the questioner if he knew what was being done. We know that icebergs plunge into the ocean, and we ought to know that when this happens they make the largest possible wave. As soon as anyone can show what becomes of those waves and that they are not the waves that tumble and crush the ice so terribly--and, at the same time, tell where those waves come from that do the damage--it will then be time to reconsider this statement; but not till then. Icebergs are very numerous; and so are those waves. Melville says, "one body of ice set in motion crowds on ice not in motion." That is true, but the wind does not need to stop to bring about that condition of things.
Nansen's accounts of this subject are most appropriate. On page 278 of Volume I, he says: "We had kept company quite long enough with the old--now broken-up--floe, so worked ourselves a little way astern after dinner, as the ice was beginning to draw together.
"Towards evening the pressure began again in earnest, and was especially bad around the remains of our floe, so that I believe we may congratulate ourselves on having left it. It is evident that the pressure here stands in connection with--is perhaps caused by--the tidal wave. It occurs with the greatest regularity. The ice slackens twice and packs twice in twenty-four hours. The pressure has happened about 4, 5, and 6 o'clock in the morning, and almost exactly the same hour in the afternoon, and in between we have always lain for some part of the time in open water. The very great pressure just now is probably clue to the spring tide; we had new moon on the 9th, which was the first day of the pressure. Then it was just after mid-day when we noticed it, but it has been later every day, and now it is at 8 p. m."
Farther on, in the same volume, we read: "For when the packing begins in earnest it seems as though there could be no spot on the earth's surface left unshaken. First you hear a sound like the thundering rumbling of an earthquake far away on the great waste; then you hear it in several places, always coming nearer and nearer. The silent ice world re-echoes with thunders; Nature's giants are awakening to the battle. The ice cracks on every side of you, and begins to pile itself up; and all of a sudden you, too, find yourself in the midst of the struggle. There are howlings and thunderings round you; you feel the ice tremble, and hear it rumbling under your feet; there is no peace anywhere. In the semi-darkness you can see it piling and tossing itself up into high ridges nearer and nearer you--floes ten, twelve, fifteen feet thick, broken, and flung on the top of each other as if they were feather-weights. They are quite near you now, and you jump away to save your life. But the ice splits in front of you, a black gulf opens, and water streams up. You turn in another direction, but there through the dark you can just see a new ridge of moving ice-blocks coming towards you. You try another direction, but there it is the same. All around there is thundering and roaring, as of some enormous waterfall, with explosions like cannon salvoes. Still nearer you it comes. The floe you are standing on gets smaller and smaller; water pours over it; there can be no escape except by scrambling over the rolling ice-blocks to get to the other side of the pack.
But now the disturbance begins to calm down. The noise passes on, and is lost by degrees in the distance."
On page 383 Nansen begins other descriptions that are worth reproducing:
"Most violent pressures are beginning again. I must go on deck and look at it. The loud roar meets one as one opens the door. It is coming from the bow now, as well as from the stern. It is clear that the pressure ridges are being thrown up in both openings, so if they reach us we shall be taken by both ends and lifted lightly and gently out of the water. There is pressure near us on all sides. Creaking has begun in the old hummock on the port quarter; it is getting louder, and, so far as I can see, the hummock is slowly rising. A lane has opened right across the large floe on the port side; you can see the water, dark as it is. Now both pressure and noise get worse and worse; the ship shakes and I feel as if I myself were being gently lifted with the stern rail, where I stand gazing out at the welter of ice masses that resemble giant snakes writhing and twisting their great bodies out there under the quiet, starry sky, whose peace is only broken by one aurora serpent waving and flickering restlessly in the northeast.
"Saturday, January 27.--It is remarkable that we should have this strong pressure just now, with the moon in its last quarter and neap tide. This does not agree with our previous experiences; no more does the fact that the pressure the day before yesterday was from 12 a. m. to about 2 p. m., and then again at 2 a. m., and now we have had it from 7.30 to 10.30 p. m. Can land have something to do with it here, after all? The temperature to-day is 42 deg. Fahr. below zero (-41.4 deg.), but there is no wind, and we have not had such pleasant weather for walking for a long time; it feels almost mild here when the air is still.
"No, that was not the end of the pressure. When I was on deck, at a quarter to 12, roaring and trembling began in the ice forward on the port side; then suddenly came one loud boom after another, sounding out in the distance, and the ship gave a start; there was again a little pressure, and after that quietness. Strange to say, there has been no pressure since 12 o'clock last night; the ice seems perfectly quiet. The pressure ridge astern showed what violent packing yesterday's was; in one place its height was eighteen to nineteen feet above the surface of the water; floe-ice eight feet thick was broken, pressed up in square blocks, and crushed to pieces. At one point a huge monolith of such floe-ice rose high into the air. Beyond this pressure wall there was no great disturbance to be detected. There had been a little packing here and there, and the floe to port had four or five large cracks across it, which no doubt accounted for the explosion I heard last night. The ice to starboard was also cracked in several places. The pressure had evidently come from the North or N. N. E. The ridge behind us is one of the highest I have ever seen yet. I believe that if the Fram had been lying there she would have been lifted right out of the water. I walked for some distance in a northeasterly direction, but saw no signs of pressure there. When the ice has been set adrift in a certain direction by the wind blowing that way for some time, it gradually in process of drifting becomes more compressed, and when the wind dies away a reaction in the opposite direction takes place. Such a reaction must, I believe, have been the cause of Saturday's pressure, which stopped entirely as suddenly as it began. Since then there has not been the slightest appearance of movement in the ice. Probably the pressure indicates the time when the drift turned."
Concerning ice-pressure, Bernacchi, writing of his voyage in the Antarctic, on page 120, vividly conveys to the reader a picture of what he saw. "A deep sonorous roar was audible like the din of a battle; a battle indeed! A great battle of Nature was raging. We rushed down towards the shore from whence the noise came, and on reaching it a sight met our eyes which baffles description; a scene absolutely frightful in its grandeur. A moving mountain of ice had risen up; a sudden and terrible pressure had set in, was piling the ice on the shore. It extended for about eight hundred yards, and was on an average sixty feet high; the mass was moving the whole time and advancing upon the land. The grandeur of the spectacle was immense. There is nothing comparable to it, and words can in no degree convey an idea of the majesty of the scene.
"Huge blocks of ice, thousands and thousands of tons in weight, were lifted up seventy, eighty, and ninety feet with irresistible force to the top of the mount. They would totter for a few seconds, and then come crashing down with a reverberating roar; at times great yawning gaps would appear in the mount, and the whole side would bulge out until with a fearful crash it would burst, and great blocks of ice fly into the air like so many straws."
This great disturbance lasted a little more than an hour. There is no account of any storm or wind, so its cause must be accounted for in some other way. We will call it a set of mammoth waves started by the plunging of an iceberg into the ocean.
The indefatigable Peary, on page 30, describes the effect of ice-pressure: "One forenoon the barometer dropped rapidly, and in the afternoon the snow ceased, the clouds lifted, and a tremendous swell came rolling in from the southeast. Not a breath of wind disturbed the surface as the long, lazy swells, smoothed by the pressure of the ice through which they passed, came slipping noiselessly in, lifting and dropping the, huge bergs as if they were but corks."
Can anyone read the description of ice-pressure, as given here, and say it was not a set of tidal waves, or large waves, set in motion by some powerful influence? What is more irresistible than an immense iceberg plunging into the ocean--one, for instance, a mile long, a thousand feet thick, and half a mile wide, under fair speed when it strikes the ocean? Such a berg would go to the bottom unless there was a depth of many thousand feet. Imagine, if possible, the commotion produced.