504 
ISLAND LIFE. 
[part II. 
and that the radically different distribution of land and sea in 
the northern and southern hemispheres has generally led to 
great diversity of climate in the Arctic and Antarctic regions. 
The form and arrangement of the continents is shown to he 
such as to favour the transfer of warm oceanic currents to the 
north far in excess of those which move towards the south, and 
whenever these currents had free passage through the northern 
land-masses to the polar area, a mild climate must have pre- 
vailed over the whole northern hemisphere. It is only in very 
recent times that the great northern continents have become 
so completely consolidated as they now are, thus shutting out 
the warm water from their interiors, and rendering possible 
a wide-spread and intense glacial epoch. But this great 
climatal change was actually brought about by the high 
excentricity which occurred about 200,000 years ago; and 
it is doubtful if a similar glaciation in equally low latitudes 
could be produced by means of any such geographical com- 
binations as actually occur, without the concurrence of a high 
excentricity. 
A survey of the present condition of the earth supports this 
view, for though we have enormous mountain ranges in every 
latitude, there is no glaciated country south of Greenland in 
N. Lat. Gl°. But directly we go back a very short period, 
we find the superficial evidences of glaciation to an enormous 
extent over three-fourths of the globe. In the Alps and Pyre- 
nees, in the British Isles and Scandinavia, in Spain and the 
Atlas, in the Caucasus and the Himalayas, in Eastern North 
America and west of the Rocky Mountains, in the Andes, in 
the Mountains of Brazil, in South Africa, and in New Zealand, 
huge moraines and other unmistakable ice-marks attest the 
universal descent of the snow-line for several thousand feet 
below its present level. If we reject the influence of high 
excentricity as the cause of this almost universal glaciation, 
we must postulate a general elevation of all these mountains 
about the same time — for the close similarity in the state of 
preservation of the ice-marks and the known activity of denu- 
dation as a destroying agent, forbid the idea that they belong 
to widely separated epochs. It has, indeed, been suggested, 
