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These rounded rocks are called "roches moutonnees," because at the distance they look like sheep lying down. You have only to look at the stream flowing from the mouth of a glacier to see what a quantity of soil it has ground off from the bottom of the valley; for the water is thick, and coloured a deep yellow by the mud it carries.
Polished rocks, as distinct as possible; moraines continuous over large spaces; stratified drift, as on the borders of the glacier of Grindelwald; in short, all the usual accompaniments of the glaciers are there, and one may follow the "roches moutonnees" with the eye to a great distance. Albany is the seat of government of the State of New York.
As the forces both of pressure and propulsion are enormous, the sand acting like emery polishes the surface; the pebbles, like coarse gravers, scratch and furrow it; and the large stones scoop out grooves in it. Lastly, projecting eminences of rock, called "roches moutonnees," are smoothed and worn into the shape of flattened domes where the glaciers have passed over them.
With the exception of the rounded surfaces so well known in Switzerland as the roches moutonnées heretofore alluded to, which may be seen in many localities, and the boulders of Erreré, the direct traces of glaciers as seen in other countries are wanting here.
Fundamental Rocks, polished, grooved, and scratched. Abrading and striating Action of Glaciers. Moraines, Erratic Blocks, and "Roches Moutonnees." Alpine Blocks on the Jura. Continental Ice of Greenland. Ancient Centres of the Dispersion of Erratics. Transportation of Drift by floating Icebergs. Bed of the Sea furrowed and polished by the running aground of floating Ice- islands.
In fact, these low hills may be considered as a succession of roches moutonnées, trending in a continuous ridge from east to west, over which the masses of northern ice have moved unimpeded to the latitude of the Ohio.
It is not only, however, by tracking the boulders back to their origin in the North that we ascertain the starting-point of the whole mass; we have another kind of evidence to this effect, already alluded to in the description of the roches moutonnées.
There is, however, no decided modification of their general trend in consequence of the range of hills intersecting them at right angles for nearly the whole width of the continent between latitudes forty-six and fifty; indeed, the Canadian, or, as they are sometimes called, the Laurentian Hills, formed a no more powerful barrier to the onward progress of the immense fields of ice covering the continent than did the small hummocks, or roches moutonnées, in the Swiss valleys to the advance of the Alpine glaciers.
Frequently it has been worn to the smooth, rounded hummocks known as roches moutonnees, and even rocky hills have been thus smoothed to flowing outlines like roches moutonnees on a gigantic scale. The rock pavement beneath the drift is also marked by long, straight, parallel scorings, varying in size from deep grooves to fine striae as delicate as the hair lines cut by an engraver's needle.
Thus, a glacier is constantly breaking off blocks and making angular surfaces, and then grinding off the angles both of the fragments and the bed, and thus forming rounded bowlders and moutonnées surfaces. Its erosion is a constant process of alternate rough hewing and planing.
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