Meager as this information is, it is about all we know of the surface of the globe within the Antarctic circle; and it will be extremely difficult to learn much more. In a latitude much farther from the pole than that where in the north vegetation is abundant, and men and animals live all the year round, the severity of the Antarctic climate cuts off all life, and constantly seals the water under a cap of ice. The coasts and outlying islands thus far examined appear to be wholly volcanic, often composed of nothing but alternate layers of ashes and ice; but the _Challenger_ staff dredged up from the edge of the ice south of the middle of the Indian Ocean pieces of granite-like and other rocks, such as belong to land regularly formed; so that probably the whole uplift does not consist of volcanic materials; and, furthermore, rocks containing fossil plants have been found on some of the southernmost islands which show that in past ages—the period of the coal deposits—the climate of that end of the world was mild enough to support forests of trees and, doubtless, a large variety of herbage and animals. Now most of the coast is unapproachable on account of a border of sea-ice, or else cliffs of moving land-ice (glaciers) that give off the flat, table-topped icebergs characteristic of the south polar waters. No trace of any land animal—except visiting sea-fowl—has been found, and only a little of the simplest plants (lichens); nor is this surprising when we learn that the highest noonday heat of summer is only a little above the freezing-point. Why this intense cold and dreadful desolation exists so much farther from the pole in the southern than in the northern hemisphere, I need hardly explain to you; for you will recall that in the north the continents are so broad as to form almost an unbroken wall about the narrow polar sea, confining its cold waters, warming the air by wide radiation, and guiding the heated flood of the Gulf Stream straight into the northern sea. In the southern hemisphere, on the other hand, an immense breadth of ocean south of latitude 40° is broken by no land of any account, and the southward flowing warm water from the equator becomes spread out so thin upon the vast surface that it is rapidly chilled. It is now generally believed, as has been hinted, that the south polar region is a continental mass, deeply buried in an ice-sheet that is ever fed in the center as fast as it wastes away at the circumference; for the prevailing winds there tend toward the pole from all sides, and carry loads of moisture to be condensed and fall in ceaseless snows. [Illustration: ICE-CLIFFS AND TABLE-TOPPED BERGS, CHARACTERISTIC OF THE ANTARCTIC REGION.]