At This Period, When The
Mountains Of Wales Were Full Of Glaciers, And The Mountainous
Parts Of Central Europe, And
Much of America north of the great
lakes, were covered with snow and ice, and had a climate
resembling that
Of Labrador and Greenland at the present day, an
Arctic flora covered all these regions. As this epoch of cold
passed away, and the snowy mantle of the country, with the
glaciers that descended from every mountain summit, receded up
their slopes and towards the north pole, the plants receded also,
always clinging as now to the margins of the perpetual snow line.
Thus it is that the same species are now found on the summits of
the mountains of temperate Europe and America, and in the barren
north-polar regions.
But there is another set of facts, which help us on another step
towards the case of the Javanese mountain flora. On the higher
slopes of the Himalayas, on the tops of the mountains of Central
India and of Abyssinia, a number of plants occur which, though
not identical with those of European mountains, belong to the
same genera, and are said by botanists to represent them; and
most of these could not exist in the warm intervening plains. Mr.
Darwin believes that this class of facts can be explained in the
same way; for, during the greatest severity of the glacial epoch,
temperate forms of plants will have extended to the confines of
the tropics, and on its departure, will have retreated up these
southern mountains, as well as northward to the plains and hills
of Europe.
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