Or, on the other hand, the comet may, as described in some of the legends, have struck the earth, head on, amid-ships, and the shock may have changed the angle of inclination of the earth’s axis, and thus have modified

[1.  Schellen, “Spectrum Analysis,” p. 392.]

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permanently the climate of our globe; and to this cause we might look also for the great cracks and breaks in the earth’s surface, which constitute the fiords of the sea-coast and the trap-extrusions of the continents; and here, too,

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THE GREAT COMET OF 1811.

might be the cause of those mighty excavations, hundreds of feet deep, in which are now the Great Lakes of America, and from which, as we have seen, great cracks radiate out in all directions, like the fractures in a pane of glass where a stone has struck it.

The cavities in which rest the Great Lakes have been attributed to the ice-sheet, but it is difficult to comprehend how an ice-sheet could dig out and root out a hole, as in the case of Lake Superior, nine hundred feet deep!

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And, if it did this, why were not similar holes excavated wherever there were ice-sheets—­to wit, all over the northern and southern portions of the globe?  Why should a general cause produce only local results?

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.]