Ragnarok : the Age of Fire and Gravel. Ignatius Donnelly

Чтение книги онлайн.

СКАЧАТЬ it contains no marine fossils or relics."[1]

      Geikie says:

      "Not a single trace of any marine organism has yet been detected in true till."[2]

      Moreover, if the sea-waves made these great deposits, they must have picked up the material composing them either from the shores of the sea or the beds of streams. And when we consider the vastness of the drift-deposits, extending, as they do, over continents, with a depth of hundreds of feet, it would puzzle us to say where were the sea-beaches or rivers on the globe that could produce such inconceivable quantities of gravel, sand, and clay. The production of gravel is limited to a small marge of the ocean, not usually more than a mile wide, where the waves and the rocks meet. If we suppose the whole shore of the oceans around the northern half of America to be piled up with gravel five hundred feet thick, it would go but a little way to form the immense deposits which stretch from the Arctic Sea to Patagonia.

      The stones of the "till" are strangely marked, striated, and scratched, with lines parallel to the longest diameter. No such stones are found in river-beds or on sea-shores.

      Geikie says:

      "We look in vain for striated stones in the gravel which the surf drives backward and forward on a beach,

      [1. Dana's "Text-Book," p. 220.

      2. "The Great Ice Age," p. 15.]

      {p. 12}

      and we may search the detritus that beaches and rivers push along their beds, but we shall not find any stones at all resembling those of the till."[1]

      But we need not discuss any further this theory. It is now almost universally abandoned.

      We know of no way in which such waves could be formed; if they were formed, they could not find the material to carry over the land; if they did find it, it would not have the markings which are found in the Drift, and it would possess marine fossils not found in the Drift; and the waves would not and could not scratch and groove the rock-surfaces underneath the Drift, as we know they are scratched and grooved.

      Let us then dismiss this hypothesis, and proceed to the consideration of the next.

      [1. "The Great Ice Age," p. 69.]

      {p. 13}

      CHAPTER IV.

      WAS IT CAUSED BY ICEBERGS?

      WE come now to a much more reasonable hypothesis, and one not without numerous advocates even to this day, to wit: that the drift-deposits were caused by icebergs floating down in deep water over the sunken land, loaded with débris from the Arctic shores, which they shed as they melted in the warmer seas of the south.

      This hypothesis explains the carriage of enormous blocks weighing hundreds of tons from their original site to where they are now found; but it is open to many unanswerable objections.

      In the first place, if the Drift had been deposited under water deep enough to float icebergs, it would present throughout unquestionable evidences of stratification, for the reason that the larger masses of stone would fall more rapidly than the smaller, and would be found at the bottom of the deposit. If, for instance, you were to go to the top of a shot-tower, filled with water, and let loose at the same moment a quantity of cannon-balls, musket-balls, pistol-balls, duck-shot, reed-bird shot, and fine sand, all mixed together, the cannon-balls would reach the bottom first, and the other missiles in the order of their size; and the deposit at the bottom would be found to be regularly stratified, with the sand and the finest shot on top. But nothing of this kind is found in the Drift, especially in the "till"; clay, sand, gravel, stones,

      {p. 14}

      and bowlders are all found mixed together in the utmost confusion, "higgledy-piggledy, pell-mell."

      Says Geikie:

      "Neither can till owe its origin to icebergs. If it had been distributed over the sea-bottom, it would assuredly have shown some kind of arrangement. When an iceberg drops its rubbish, it stands to reason that the heavier blocks will reach the bottom first, then the smaller stones, and lastly the finer ingredients. There is no such assortment visible, however, in the normal 'till,' but large and small stones are scattered pretty equally through the clay, which, moreover, is quite unstratified."[1]

      This fact alone disposes of the iceberg theory as an explanation of the Drift.

      Again: whenever deposits are dropped in the sea, they fall uniformly and cover the surface below with a regular sheet, conforming to the inequalities of the ground, no thicker in one place than another. But in the Drift this is not the case. The deposit is thicker in the valleys and thinner on the hills, sometimes absent altogether on the higher elevations.

      "The true bowlder-clay is spread out over the region under consideration as a somewhat widely extended and uniform sheet, yet it may be said to fill up all small valleys and depressions, and to be thin or absent on ridges or rising grounds."[2]

      That is to say, it fell as a snow-storm falls, driven by high winds; or as a semi-fluid mass might be supposed to fall, draining down from the elevations and filling up the hollows.

      Again: the same difficulty presents itself which we found in the case of "the waves of transplantation." Where did the material of the Drift come from? On what sea-shore, in what river-beds, was this incalculable mass of clay, gravel, and stones found?

      [1. "The Great Ice Age," p. 72.

      2. "American Cyclopædia," vol. vi, p. 112.]

      {p. 15}

      Again: if we suppose the supply to have existed on the Arctic coasts, the question comes,

      Would the icebergs have carried it over the face of the continents?

      Mr. Croll has shown very clearly[1] that the icebergs nowadays usually sail down into the oceans without a scrap of débris of any kind upon them.

      Again: how could the icebergs have made the continuous scratchings or striæ, found under the Drift nearly all over the continents of Europe and America? Why, say the advocates of this theory, the icebergs press upon the bottom of the sea, and with the stones adhering to their base they make those striæ.

      But two things are necessary to this: First, that there should be a force great enough to drive the berg over the bottom of the sea when it has once grounded. We know of no such force. On the contrary, we do know that wherever a berg grounds it stays until it rocks itself to pieces or melts away. But, suppose there was such a propelling force, then it is evident that whenever the iceberg floated clear of the bottom it would cease to make the strive, and would resume them only when it nearly stranded again. That is to say, when the water was deep enough for the berg to float clear of the bottom of the sea, there could be no striæ; when the water was too shallow, the berg would not float at all, and there would be no striæ. The berg would mark the rocks only where it neither floated clear nor stranded. Hence we would find striæ only at a certain elevation, while the rocks below or above that level would be free from them. But this is not the case with the drift-markings. They pass over mountains and down into the deepest valleys; they are

      [1. "Climate and Time," p. 282.]

      {p. 16}

СКАЧАТЬ