who designated them by that name,
because, where they are numerous and seen from a distance, they resemble
the rounded backs of a flock of sheep resting on the ground. These
knolls are the result of the prolonged abrasion of masses of rocks
separated by deep indentations wide enough to be filled up by large
glaciers, overtopping the summits of the intervening prominences, and
passing over them like a river, or like tide-currents flowing over a
submerged ledge of rock. It is evident that water rushing over such
sunken hills or ledges, adapting itself readily to all the inequalities
over which it flows, and forming eddies against the obstacles in its
course, will scoop out tortuous furrows upon the bottom, and hollow out
rounded cavities against the walls, acting especially along preexisting
fissures and upon the softer parts of the rock,--while the glacier,
moving as a solid mass, and carrying on its under side its gigantic file
set in a fine paste, will in course of time abrade uniformly the angles
against which it strikes, equalize the depressions between the prominent
masses, and round them off until they present those smooth bulging
knolls known as the "_roches moutonnees_" in the Alps, and so
characteristic everywhere of glacier-action. A comparison of any
tide-worn hummock with such a glacier-worn mound will convince the
observer that its smooth and evenly rounded surface was never produced
by water.

Besides their peculiar form, the _roches moutonnees_ present all the
characteristic features of glacier-action in their polished surfaces
accompanied with the straight lines, grooves, and furrows above
described. But there are two circumstances connected with these knolls
deserving special notice. They frequently present the glacial marks only
on one side, while the opposite side has all the irregularities and
roughness of a hill-slope not acted upon by ice. It is evident that the
polished side was the one turned towards the advancing glacier, the side
against which the ice pressed in its onward movement,--while it passed
over the other side, the lee side as we may call it, without coming in
immediate contact with it, bridging the depression, and touching bottom
again a little farther on. As an additional evidence of this fact, we
frequently find on the lee side of such knolls accumulations of the
loose materials which the glacier carries with it. It is only, however,
when the knolls are quite high, and abrupt enough