Ragnarok : the Age of Fire and Gravel. Ignatius Donnelly

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СКАЧАТЬ red clays, which it laid down elsewhere, as the red clays are spread over that great stretch of fifteen hundred miles to which I have referred.

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      Can any one suppose that ice could so discriminate?

      And if it by any means effected this separation of the particles of granite, indissolubly knit together, how could it perpetuate that separation while moving over the land, crushing all beneath and before it, and leave it on the face of the earth free from commixture with the surface rocks?

      Again: the ice-sheets which now exist in the remote north do not move with a constant and regular motion southward, grinding up the rocks as they go. A recent writer, describing the appearance of things in Greenland, says:

      "The coasts are deeply indented with numerous bays and fiords or firths, which, when traced inland, are almost invariably found to terminate against glaciers. Thick ice frequently appears, too, crowning the exposed sea-cliffs, from the edges of which it droops in thick, tongue-like, and stalactitic projections, until its own weight forces it to break away and topple down the precipices into the sea."[1]

      This does not represent an ice-sheet moving down continuously from the high grounds and tearing up the rocks. It rather breaks off like great icicles from the caves of a house.

      Again: the ice-sheets to-day do not striate or groove the rocks over which they move.

      Mr. Campbell, author of two works in defense of the iceberg theory--"Fire and Frost," and "A Short American Tramp"--went, in 1864, to the coasts of Labrador, the Strait of Belle Isle, and the Gulf of St. Lawrence, for the express purpose of witnessing the effects of icebergs, and testing the theory he had formed. On the coast of Labrador he reports that at Hanly Harbor, where

      [1. "Popular Science Monthly," April, 1874, p. 646.]

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      the whole strait is blocked up with ice each winter, and the great mass swung bodily up and down, "grating along the bottom at all depths," he "found the rocks ground smooth, but not striated."[1] At Cape Charles and Battle Harbor, he reports, "the rocks at the water-line are not striated."[2] At St. Francis Harbor, "the water-line is much rubbed smooth, but not striated."[3] At Sea Islands, he says, "No striæ are to be seen at the land-wash in these sounds or on open sea-coasts near the present waterline."[4]

      Again: if these drift-deposits, these vast accumulations of sand, clay, gravel, and bowlders, were caused by a great continental ice-sheet scraping and tearing the rocks on which it rested, and constantly moving toward the sun, then not only would we find, as I have suggested in the case of glaciers, the accumulated masses of rubbish piled up in great windrows or ridges along the lines where the face of the ice-sheet melted, but we would naturally expect that the farther north we went the less we would find of these materials; in other words, that the ice, advancing southwardly, would sweep the north clear of débris to pile it up in the more southern regions. But this is far from being the case. On the contrary, the great masses of the Drift extend as far north as the land itself. In the remote, barren grounds of North America, we are told by various travelers who have visited those regions, "sand-hills and erratics appear to be as common as in the countries farther south."[5] Captain Bach tells us[6] that he saw great chains of sand-hills, stretching

      [1. "A Short American Tramp," pp. 68, 107.

      2. Ibid., p. 68.

      3. Ibid., p. 72.

      4. Ibid., p. 76.

      5. "The Great Ice Age," p. 391.

      6. "Narrative of Arctic Land Expedition to the Mouth of the Great Fish River," pp. 140, 346.]

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      away from each side of the valley of the Great Fish River, in north latitude 66°, of great height, and crowned with gigantic bowlders.

      Why did not the advancing ice-sheet drive these deposits southward over the plains of the United States? Can we conceive of a force that was powerful enough to grind up the solid rocks, and yet was not able to remove its own débris?

      But there is still another reason which ought to satisfy us, once for all, that the drift-deposits were not due to the pressure of a great continental ice-sheet. It is this:

      If the presence of the Drift proves that the country in which it is found was once covered with a body of ice thick and heavy enough by its pressure and weight to grind up the surface-rocks into clay, sand, gravel, and bowlders, then the tropical regions of the world must have been covered with such a great ice-sheet, upon the very equator; for Agassiz found in Brazil a vast sheet of "ferruginous clay with pebbles," which covers the whole country, "a sheet of drift," says Agassiz, "consisting of the same homogeneous, unstratified paste, and containing loose materials of all sorts and sizes," deep red in color, and distributed, as in the north, in uneven hills, while sometimes it is reduced to a thin deposit. It is recent in time, although overlying rocks ancient geologically. Agassiz had no doubt whatever that it was of glacial origin.

      Professor Hartt, who accompanied Professor Agassiz in his South American travels, and published a valuable work called "The Geology of Brazil," describes drift-deposits as covering the province of Pará, Brazil, upon the equator itself. The whole valley of the Amazon is covered with stratified and unstratified and unfossiliferous

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      Drift,[1] and also with a peculiar drift-clay (argile plastique bigarrée), plastic and streaked.

      Professor Hartt gives a cut from which I copy the following representation of drift-clay and pebbles overlying a gneiss hillock of the Serra do Mar, Brazil:

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      DRIFT-DEPOSITS IN THE TROPICS.

      a, drift-clay; f f, angular fragments of quartz; c. sheet of pebbles; d d, gneiss in situ; g g, quartz and granite veins traversing the gneiss.

      But here is the dilemma to which the glacialists are reduced: If an ice-sheet a mile in thickness, or even one hundred feet in thickness, was necessary to produce the Drift, and if it covered the equatorial regions of Brazil, then there is no reason why the same climatic conditions should not have produced the same results in Africa and Asia; and the result would be that the entire globe, from pole to pole, must have rolled for days, years, or centuries, wrapped in a continuous easing, mantle, or shroud of ice, under which all vegetable and animal life must have utterly perished.

      [1. "Geology of Brazil," p. 488.]

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      And we are not without evidences that the drift-deposits are found in Africa. We know that they extend in Europe to the Mediterranean. The "Journal of the Geographical Society" (British) has a paper by George Man, F. G. S., on the geology of Morocco, in which he says:

      "Glacial moraines may be seen on this range nearly eight thousand feet above the sea, forming gigantic ridges and mounds of porphyritic blocks, in some places damming up the ravines, and at the foot of Atlas are enormous mounds of bowlders."

      These mounds oftentimes rise two thousand feet above the level of the plain, and, according to Mr. Man, were produced by glaciers.

      We shall see, hereafter, that the sands bordering Egypt belong to the Drift age. The diamond-bearing gravels of South Africa extend СКАЧАТЬ