Now, good reader, we have reasoned together up to this point. To be sure, I have done most of the talking, while you have indulged in what the Rev. Sydney Smith called, speaking of Lord Macaulay, "brilliant flashes of silence."
But I trust we agree thus far that neither water nor ice caused the Drift. Water and ice were doubtless associated with it, but neither produced it.
What, now, are the elements of the problem to be solved?
First, we are to find something that instantaneously increased to a vast extent the heat of our planet, vaporized the seas, and furnished material for deluges of rain, and great storms of snow, and accumulations of ice north and south of the equator and in the high mountains.
Secondly, we are to find something that, coming from above, smashed, pounded, and crushed "as with a maul," and rooted up as with a plow, the gigantic rocks of the surface, and scattered them for hundreds of miles from their original location.
Thirdly, we are to find something which brought to the planet vast, incalculable masses of clay and gravel, which did not contain any of the earth's fossils; which, like the witches of Macbeth,
Look not like th' inhabitants of earth,
And yet are on it; "
which are marked after a fashion which can not be found anywhere else on earth; produced in a laboratory which has not yet been discovered on the planet.
Fourthly, we are to find something that would produce cyclonic convulsions upon a scale for which the ordinary operations of nature furnish us no parallel.
Fifthly, we are to find some external force so mighty that it would crack the crust of the globe like an eggshell, lining its surface with great rents and seams, through which the molten interior boiled up to the light.
Would a comet meet all these prerequisites?
I think it would.
Let us proceed in regular order.