And it appears from the geographical explanations given in preceding pages of the general movements of the winds and currents of the sea how impossible it is for heat to be conveyed to the antarctic latitudes sufficient to prevent the growth of glaciers on their lands while the Cape Horn channel is in possession of its present capacity. For, as has been shown, this channel furnishes opportunity for the westerly winds to impel the surface waters of the great southern ocean constantly around the globe, and so largely turns away the tropical currents from the high southern latitudes. Consequently, there seems to be no method yet devised through nature’s mode of action that can carry sufficient heat into the antarctic latitudes to melt the ice-sheets from the southern continent, or even arrest their growth, while the Cape Horn channel maintains its present width and depth. Therefore, the increase of glaciers and icebergs will slowly continue until a glacial epoch is perfected. And it seems that this arrangement for bringing about a frigid age made slower progress in its early stage than at this date, owing to there having been a lack of glacial ice in the polar regions to produce icebergs for cooling the ocean waters. But the independent circulation of the great southern ocean, after turning away the tropical currents from the high southern latitudes for thousands of years, did at length cause glaciers to form on the antarctic lands, which have been slowly, but constantly increasing; and, consequently, the cooling of the ocean has been accelerated proportionate to the increase of ice-sheets. Therefore, with the cooling process so well advanced as it now appears to be, it seems that more than half of the time required to bring a frigid age to perfection has been expended since ice-sheets began to gather on the antarctic shores. For, when we realise how the facilities for making ice have advanced through the increase of glaciers in both hemispheres, and how large a portion of the ocean waters have been cooled below a temperate or tropical temperature even in the torrid latitudes where the warm upper waters of the ocean have been reduced to a comparatively thin stratum when compared to the vast bulk of the cooled under-waters, it appears that the cold will increase at a faster rate for the next thousand years than was the case during the last ten centuries. Therefore, the climate will be less favorable for plants and animals existing on lands in the high latitudes for the next thousand years than during the ten centuries preceding; and, when we take into consideration the accelerative growth of a frigid epoch, it seems that the increasing cold will in a few thousand years drive the greater portion of both plants and animals from the now temperate latitudes to maintain an existence in the tropical zone, where a large part of the existing species of such life must have taken refuge during the last ice period.