As limits; but in none of these schemes has the coast of Antarctica been adequately considered, and they have all been too much influenced by the Mercator map. Each of the three oceans, Atlantic, Indian and Pacific, possesses an Antarctic facies in the southern part and a tropical facies between the tropics, and the Atlantic and Pacific an Arctic facies in their northern parts.
Modern naturalists consider that many of the problems of Australia's remarkable fauna and flora can be best explained by the following hypothesis: - The region now covered by the antarctic ice-cap was in early Tertiary times favoured by a mild climate; here lay an antarctic continent or archipelago.
The voyage of Drake across the Pacific was preceded by that of Alvaro de Mendana, who was despatched from Peru in 1567 to discover the great Antarctic continent which was believed to extend far northward into the South sea, the search In Pacific. for which now became one of the leading motives of Pacific. exploration.
The north to south distance from Bering Strait to the Antarctic circle is 9300 m., and the Pacific attains its greatest breadth, 10,000 m., at the equator.
The west wind drift sends a stream northwards along the west coast of Australia, the West Australia current, the homologue of the Benguela current in the South Atlantic. The principal feature in the circulation in the depths of the Indian Ocean is a slow movement of Antarctic water northwards along the bottom to take the place of that removed from the surface by evaporation, and by currents in the lower latitudes.
It is not to be supposed that this antarctic element, to which Professor Tate has applied the name Euronotian, entered a desert barren of all life.
For purposes of measurement the polar boundaries are taken to be the Arctic and Antarctic circles, although in discussing the configuration and circulation it is impossible to adhere strictly to these limits.
It must be remembered that the Arabs, who inhabit an extremely hot country, are very fully clothed, while the Fuegians at the extremity, of Cape Horn, exposed to all the rigours of an antarctic climate, have, as sole protection, a skin attached to the body by cords, so that it can be shifted to either side according to the direction of the wind.
Cook's second voyage was mainly intended to settle the question of the existence of such a continent once for all, and to define the limits of any land that might exist in navigable seas towards the Antarctic circle.
On the other hand, recent Antarctic exploration makes it practically certain that a great continent surrounds the south pole with a total area considerably more than Sir John Murray's estimate in 1894, when he assigned to it an area of 9,000,000 sq.