an.

Applying the data gathered by Dr. Croll for the Gulf Stream, it seems
likely that the average annual temperature induced in the Arctic Sea
by the free entrance of the Japan current would be between 20 deg. and 30 deg.
Fahr. This would convert this wide realm of waters into a field of
great evaporation, vastly increasing the annual precipitation. It
seems also certain that the greater part of this precipitation would
be in the form of snow. It appears to the writer that this cause alone
may be sufficient to account for the last Glacial period in the
northern hemisphere. As to the probability that the region about
Bering Strait may have been lowered in the manner required by this
view, it may be said that recent studies on the region about Mount St.
Elias show that during or just after the ice epoch the shores in that
portion of Alaska were at least four thousand feet lower than at
present. As this is but a little way from the land which we should
have to suppose to be lowered in order to admit the Japan current, we
could fairly conclude that the required change occurred. As for the
cause of the land movement, geologists are still in doubt. They know,
however, that the attitudes of the land are exceedingly unstable, and
that the shores rarely for any considerable time maintain their
position. It is probable that these swayings of the earth's surface
are due to ever-changing combinations of the weight in different parts
of the crust and the strains arising from the contraction of its inner
parts.

In the larger operations of Nature the effects which we behold,
however simple, are rarely the products of a single cause. In fact,
there are few actions so limited that they can fairly be referred to
one influence. It is therefore proper to state that there are many
other actions besides those above noted which probably enter into
those complicated equations which determine the climatal conditions of
the earth. To have these would carry us into difficult and speculative
inquiries.

As before remarked, all the regions which have been subjected to
glaciation are still each year brought temporarily into the glacial
state. This fact serves to show us that the changes necessary to
produce great ice sheets are not necessarily of a startling nature,
however great the consequences may be. Assuming, then, that relatively
slight alterations of climate may cause the ice sheet to come and go,
we may say that all the influences whic