458 Climate of the Glacial Period. (October, 
The same latitudes that in the era of greatest cold were 
covered with continental ice, or bore just beyond the reach 
of the great glaciers the stunted Polar willow and a few 
Arctic mosses and lichens, where the musk-ox and the 
Greenland iemming found their northern limit in summer, 
were at the commencement of the Tertiary period covered 
with subtropical forests. Palm-trees—of types now restricted 
to the Moluccas, the Phillippine islands, and Bengal,—with 
custard-apples, melons, and many another tropical and sub- 
tropical plant, flourished in the neighbourhood of Paris and 
London. Huge animals, resembling but larger than tapirs, 
roamed in these forests; monkies chattered amongst the 
trees; great tortoises crawled beneath the rank herbage; 
sea-snakes, crocodiles, and enormous sharks tenanted the 
waters. If any of the mammalia had at that time become 
adapted to live in an Arctic climate, they must have retired 
to the very Pole to find it. 
It is these two extremes of heat and cold with which we 
have to deal. If we confine ourselves to the attempt of 
accounting for the cold of the Glacial period alone, we 
grapple with but half the problem. The climate of the 
Eocene period was apparently as much warmer as that of 
the great ice age was colderthan the present. The converse 
of the cause of the one extreme in all probability produced 
the other. It has been my fortune in other branches of 
enquiry to find in one hemisphere the solution of a question 
that had puzzled me in another. For instance, the origin 
of large masses of gold in the gravel-beds of Australia, in 
distri¢ts where the auriferous lodes contained only fine grains 
of gold, remained doubtful until I found nearly at the anti- 
podes of the first observation, in Nova Scotia, that the very 
highest parts of the lodes had in some cases been left un- 
denuded, and that there the gold occurred in large pieces, 
whilst deeper only fine grains were found. ‘The conclusion 
was obvious that in Australia the tops of the quartz veins 
containing the ‘‘nuggets” had been worn off and carried 
down into the valleys. And so, in studying the Glacial 
question, it was not until I occupied myself with the con- 
sideration of its antipodes, the climate of Early Tertiary 
times, that I laid hold of facts that left in my mind little 
doubt as to what had been the prime cause of the great 
oscillations of temperature. 
When the subtropical fauna and flora lived in Central 
Europe as far as 52° N. lat., still nearer the Pole vegetation 
flourished similar to that which now characterises the milder 
portions of the temperate zones, and the representatives of 
