Continental and Island Life [pp. 1-29]

CONTINENTAL AND ISLAND LIFE.
them some facts as to the present distribution of life and of the
agencies which influence it.
If we examine Petermann's map of the ice of the north and
south polar regions, reproduced by Wallace, we shall find a remarkable contrast. In the southern polar region a space extending in all directions twenty degrees, and in some directions twentyfive degrees, is occupied with permanent snow. Thus we have
a snow-clad continent, at the outer edge of which the stratum
of solid water is at least a mile in thickness, attaining a diameter
of over 2000 miles. Around this we have floating ice dispersed
in all directions, on the Atlantic side beyond the parallel of 40~0,
and on the Pacific side only a little short of this. In other
words, we have a distribution of floating ice, bearing with it
stones and other land material, over a radius of about 3000 nautical miles from the south pole. This is an extension of polar ice
nearly equal to that which occurred in the northern hemisphere
in the great glacial age, and as it evidently results from the existence of a compact mass of high land serving as a condensingground for the aqueous vapor of the surrounding ocean, we
have only to imagine a few spurs of high ground like Greenland
projecting from the antarctic continent to render the present
glacial age of the southern hemisphere even more severe than
that of the Pleistocene probably was in the north. As it now
is, Heard's Island, in south latitude 53~, is glaciated down to the
sea, and New Zealand, in south latitude 43~ 35', has a glacier
descending to within 705 feet of the sea.'
If we turn now to the north polar region, the case is very
different. Here the area of permanent ice is scarcely more than
half that of the south pole, and if we were to remove the exceptionally high and ice-covered tract of Greenland it would be
scarcely more than one third. The distribution of floating ice is
in like manner limited to a narrow belt along the west side of the
north Atlantic and to the coasts of the most northern part of
the Pacific. Geological facts indicate that within a comparatively recent period the state of matters in the north was much
less favorable as to temperature, but that previously to this for
1 It is a significant fact that while in latitudes lower than 40~ the southern
hemisphere is the colder, in higher latitudes it is the warmer. Thus a glacial age
may affect temperate latitudes more than those which are polar.
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