all its
details upon our observation. In my present position, now that the lapse
of many years separates me from my personal investigations of the
ancient and modern glaciers, and I look back upon them from another
continent, it seems to me that I have, as it were, a bird's-eye view of
their whole extent; and I confess that this distant retrospect of the
subject has been to me almost as fascinating as were the researches of
my earlier years in the same direction. I wish that I could present it
to the minds of my readers with something of the attraction it possesses
for me. I trust, however, that I have made it plain to them that the
great mountain-chain of the Alps has been a central axis from which
immense glaciers at one time descended in every direction, not only to
its base, beyond which the lowlands extend in flat undulations, but to a
greater or less distance over the adjoining plains; while at present
they are confined to the higher valleys. So far, then, notwithstanding
the extraordinary difference in their dimensions, at the time they
reached the Jura and the plain of Northern Italy, when compared with
what they are now, they seem directly connected with the Alps, and the
mountains appear as their birthplace; so much so that the first attempts
at a generalization concerning their origin started from the assumption
that they must have been formed between the high ridges from which they
seem to flow down. These facts, then the only ones known concerning a
greater extension of the glaciers, naturally led to the views advocated
by M. de Charpentier. My own theory was also at first, that the upheaval
of the Alps must, in some way or other, have been connected with these
phenomena. But it soon became evident to me that these views were
inadequate to account for the former presence of extensive glaciers in
other parts of Europe; and even within the range of the Alps there were
insuperable objections to their final admission. If the ancient glaciers
had been first formed among the highest mountains, and extended
downwards into the plains, the largest and highest moraines ought to be
the most distant, and to be formed of the most rounded masses; whereas
the actual condition of the detrital accumulations is the reverse, the
distant materials being widely spread, and true moraines being found
only in valleys connected with great chains of lofty mountains.

Again, all these moraines are within one another,--the most distant