A gentleman named Trimmer, who, alas! is now dead, was, I believe, the first to find it out.

He knew that along the coast of Labrador, and other cold parts of North America, and on the shores, too, of the great river St.Lawrence, the stranded icebergs, and the ice-foot, as it is called, which is continually forming along the freezing shores, grub and plough every tide into the mud and sand, and shove up before them, like a ploughshare, heaps of dirt; and that, too, the ice itself is full of dirt, of sand and stones, which it may have brought from hundreds of miles away; and that, as this ploughshare of dirty ice grubs onward, the nose of the plough is continually being broken off, and left underneath the mud; and that, when summer comes, and the ice melts, the mud falls back into the place where the ice had been, and covers up the gravel which was in the ice.

So, what between the grubbing of the ice-plough into the mud, and the dirt which it leaves behind when it melts, the stones, and sand, and mud upon the shore are jumbled up into curious curved and twisted layers, exactly like those which Mr.Trimmer saw in certain gravel-pits.

And when I first read about that, I said, "And exactly like what I have been seeing in every gravel-pit round here, and trying to guess how they could have been made by currents of water, and yet never could make any guess which would do." But after that it was all explained to me; and I said, "Honour to the man who has let Madam How teach him what she had been trying to teach me for fifteen years, while I was too stupid to learn it.
Now I am certain, as certain as I can be of any earthly thing, that the whole of these Windsor Forest Flats were ages ago ploughed and harrowed over and over again, by ice-floes and icebergs drifting and stranding in a shallow sea." And if you say, my dear child, as some people will say, that it is like building a large house upon a single brick to be sure that there was an iceberg sea here, just because I see a few curlicues in the gravel and sand--then I must tell you that there are sometimes--not often, but sometimes--pages in Madam How's book in which one single letter tells you as much as a whole chapter; in which if you find one little fact, and know what it really means, it makes you certain that a thousand other great facts have happened.

You may be astonished: but you cannot deny your own eyes, and your own common sense.