l as it moved over it, but bridging the opposite side in
its descent without coming into contact with it.[I] This is true, not
only of hills, but of much slighter obstacles which presented themselves
in the path of the ice. Even pebbles imbedded in masses of
pudding-stone, but rising sometimes above the level of the general
surface, often have their northern side polished and scratched, while
the southern one remains untouched.

Moraines are not wanting to complete the chain of evidence respecting
the ancient existence of glaciers in this country, although we cannot
expect to find them here so frequently as in Europe, where the many
local glaciers in circumscribed valleys afforded special facilities for
the building up of these lateral and transverse walls. Over the broad
expanse of the United States, on the contrary, with such slight
variations of level, the disappearance of the ice at its breaking-up
would naturally be more complete and continuous than in a country
intersected by frequent mountain-chains, where the ice would linger in
the higher valleys long after it had disappeared from the plains below.
Yet it is evident that here also in certain localities the boundary-line
of the ice underwent oscillations, pausing here and there long enough to
collect mounds of the same character as those spanning the valleys of
Switzerland and Great Britain. We have several of these mounds in our
immediate vicinity. The Waverley Oaks, so well known to all lovers of
fine trees in our community, stand on an ancient moraine, and there are
others in the neighborhood of the Blue Hills. In the southeastern parts
of Maine, also, I have observed very well-defined moraines. In Vermont,
the valley of the Winooski River retains ample traces of the local
glacier by which it was formerly filled; and, indeed, throughout the
Alleghany range, in its northeastern as well as its southern extension,
we have various evidences of localized glaciers, which must have
outlived the general ice-period for a longer or shorter time.

I am unwilling to weary my readers by dwelling upon appearances
identical with those already described; but I may state, for the
guidance of those who wish to investigate these traces for themselves,
that any recently uncovered ledge of rock in our neighborhood, the
surface of which has not been altered by atmospheric agencies, presents
the glacier-worn surfaces with the characteristic _striae_ and furrows.
These marks may be