Ragnarok: The Age of Fire and Gravel | Page 6

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 Cyclop?dia," vol. vi, p. 112.]
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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 stri?, 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 stri?.
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 stri?; when the water was too shallow, the berg would not float at all, and there would be no stri?. The berg would mark the rocks only where it neither floated clear nor stranded. Hence we would find stri? 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.]
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universal within very large areas; they cover the face of continents and disappear under the waves of the sea.
It is simply impossible that the Drift was caused by icebergs. I repeat, when they floated clear of the rocks, of course they would not mark them; when the water was too shallow to permit them to float at all, and so move onward, of course they could not mark them. The striations would occur only when the water was; just deep enough to float the berg, and not deep enough to raise the berg clear of the rocks; and but a small part of the bottom of the sea could fulfill these conditions.
Moreover, when the waters were six thousand feet deep in New England, and four thousand feet deep in Scotland, and over the tops of the Rocky Mountains, where was the rest of the world, and the life it contained?
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CHAPTER V.
WAS IT CAUSED BY GLACIERS?
WHAT is a glacier? It is a river of ice, crowded by the weight of mountain-ice down into some valley, along which it descends by a slow, almost imperceptible motion, due to a power of the ice, under the force of gravity, to rearrange its molecules. It is fed by the mountains and melted by the sun.
The glaciers are local in character, and comparatively few in number; they are confined to valleys having some general slope downward. The whole Alpine mass does not move down upon the plain. The movement downward is limited to these glacier-rivers.
The glacier complies with some of the conditions of the problem. We can suppose it capable of taking in its giant paw a mass of rock, and using it as a graver to carve deep grooves in the rock below it; and we can see in it a great agency for breaking up rocks and carrying the detritus down upon the plains. But here the resemblance ends.
That high authority upon this subject, James Geikie, says:
"But we can not fail to remark that, although scratched and polished stones occur not infrequently in the frontal moraines of Alpine glaciers, yet at the same time these moraines do not at all resemble till. The moraine consists for the most part of a confused heap of rough angular stones and blocks, and loose sand and _débris_; scratched
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stones are decidedly in the minority, and indeed