e areas above the line of perpetual snow; that {97} about the
same time Scandinavia, the Alps, and the Pyrenees received a similar
increase of altitude; and that, almost simultaneously, Eastern North
America, the Sierra Nevada of California, the Caucasus, Lebanon, the
southern mountains of Spain, the Atlas range, and the Himalayas, were each
some thousands of feet higher than they are now; for all these mountains
present us with indications of a recent extension of their glaciers, in
superficial phenomena so similar to those which occur in our own country
and in Western Europe, that we cannot suppose them to belong to a different
epoch. Such a supposition is rendered more difficult by the general
concurrence of scientific testimony to a partial submergence during the
glacial epoch, not only in all parts of Britain, but in North America,
Scandinavia, and, as shown by the wide extension of the drift, in Northern
Europe; and when to this we add the difficulty of understanding how any
probable addition to the altitude of our islands could have brought about
the extreme amount of glaciation which they certainly underwent, and when,
further, we know that a phase of very high excentricity did occur at a
period which is generally admitted to agree well with physical evidence of
the time elapsed since the cold passed away, there seems no sufficient
reason why such an agency should be ignored.

No doubt a prejudice has been excited against it in the minds of many
geologists, by its being thought to lead _necessarily_ to frequently
recurring glacial epochs throughout all geological time. But I have here
endeavoured to show that this is _not_ a necessary consequence of the
theory, because a concurrence of favourable geographical conditions is
essential to the initiation of a glaciation, which when once initiated has
a tendency to maintain itself throughout the varying phases of precession
occurring during a period of high excentricity. When, however, geographical
conditions favour warm Arctic climates--as it has been shown they have done
throughout the larger portion of geological time--then changes of
excentricity, to however great an extent, have no tendency to bring about a
state of glaciation, because warm oceanic currents have a {98}
preponderating influence, and without very large areas of high northern
land to act as condensers, no perpetual snow is possible, and hence the
initial process of glaciation does not occur.

The t