Sir Charles Lyell shows[1] that glaciers do not cut out holes like the depressions in which the Great Lakes lie; he also shows that these lakes are not due to a sinking down of the crust of the earth, because the strata are continuous and unbroken beneath them. He also calls attention to the fact that there is a continuous belt of such lakes, reaching from the northwestern part of the United States, through the Hudson Bay Territory, Canada, and Maine, to Finland, and that this belt does not reach below 50° north latitude in Europe and 40° in America. Do these lie in the track of the great collision? The comet, as the striæ indicate, came from the north. The mass of Donati's comet was estimated by MM. Faye and Roche at about the seven-hundredth part of the bulk of the earth. M. Faye says: "That is the weight of a sea of forty thousand square miles one hundred and nine yards deep; and it must be owned that a like mass, animated with considerable velocity, might well produce, by its shock with the earth, very perceptible results."[2] We have but to suppose, (a not unreasonable supposition,) that the comet which struck the earth was much larger than Donati's comet, and we have the means of accounting for results as prodigious as those referred to. We have seen that it is difficult to suppose that ice produced the drift-deposits, because they are not found where ice certainly was, and they are found where ice certainly was not. But, if the reader will turn to the [1. "Elements of Geology," pp. 168,171, _et seq_. 2. "The Heavens," p. 260.] {p. 97} illustration which constitutes the frontispiece of this volume, and the foregoing engraving on page 93, he will see that the Drift is deposited on the earth, as it might have been if it had suddenly fallen from the heavens; that is, it is on one side of the globe--to wit, the side that faced the comet as it came on. I think this map is substantially accurate. There is, however, an absence of authorities as to the details of the drift-distribution. But, if my theory is correct, the Drift probably fell at once. If it had been twenty-four hours in falling, the diurnal revolution would, in turn, have presented all sides of the earth to it, and the Drift would be found everywhere. And this is in accordance with what we know of the rapid movements of comets. They travel, as I have shown, at the rate of three hundred and sixty-six miles per second; this is equal to twenty-one thousand six hundred miles per minute, and one million two hundred and ninety-six thousand miles per hour! And this accords with what we know of the deposition of the Drift. It came with terrific force. It smashed the rocks; it tore them up; it rolled them over on one another; it drove its material _into_ the underlying rocks; "it _indented it_ into them," says one authority, already quoted.