OF THE KERGUELEN REGION OE THE GREAT SOUTHERN OCEAN. 347 



deposit for the most part composed of the dead shells of pelagic Foraminifera — the 

 well-known Globigerina Ooze. This calcareous deposit appears to form a continuous 

 band rigdit around the world to the north of the Diatom Ooze. 



In great depths, however, as for instance to the west of Tasmania in 2600 fathoms 

 (4755 m.), a Eed Clay occupies the sea-bed. The peroxides of iron and manganese make 

 up a large part of this Eed Clay, and in it are embedded manganese nodules, zeolitic 

 crystals, magnetic spherules with metallic nuclei of extra-terrestrial origin, thousands of 

 sharks' teeth, ear-bones and other bones of whales or other Cetaceans. The Eed Clay 

 deposit with all these special characteristics is especially well developed on the northern 

 limits of the Great Southern Ocean in the Pacific. In the composition of all these 

 deposits the physical conditions of the surface waters are reflected. The Blue Muds 

 with abundant boulders indicate a sea very frequently covered with floating icebergs. 

 The Diatom Ooze indicates cold surface water of a low specific gravity, and with clayey 

 matter in suspension. The Globigerina Ooze indicates the warmer water of the temperate 

 regions with numerous pelagic organisms having calcareous shells and skeletons, such 

 as Coccospheres, Foraminifera and shelled Molluscs. 



Meteorology. — There is a wide range of temperature of both the air and sea-water 

 within the limits of the Great Southern Ocean. In the neighbourhood of the Antarctic 

 Circle the temperature of the air and sea-surface is, even in summer, at or below the 

 freezing-point of fresh water. Direct observations have, in these latitudes, only been 

 made during the summer, so that we have no certain knowledge of the air temperature 

 during the winter months, nor of the annual range of temperature. In all probability 

 the range of the water temperature at the Antarctic Circle throughout the year is not 

 greater than three or four degrees Fall, (about two degrees Cent.), and the sea in these 

 latitudes must always be burdened with floating ice. Indeed, with the exception of an 

 area to the south of Australia and New Zealand, the whole area of the Southern Ocean 

 may be occasionally affected with floating ice from the Antarctic Continent ; the extreme 

 limit within which drift ice has been observed extends to the north of the 40th parallel 

 of south latitude in the Atlantic, and nearly to this parallel at some points of the Pacific 

 and Indian Oceans. 



At the northern limits of the Southern Ocean on the 40th parallel south there is a 

 wide annual range of temperature, both of the air and of the sea-surface. At some points 

 the range is over 50° F. (about 28° C.) in the case of the air, and over 31° F. (about 

 17° C.) in the case of the water, for instance, off the Agulhas Bank. These great varia- 

 tions in the temperature of the sea-surface are brought about chiefly by a mixture of 

 oceanic currents from a tropical source on the one hand and from a south polar source on 

 the other. One result of this mixture of currents from different sources is the destruc- 

 tion of large numbers of pelagic organisms in the surface waters of the Southern Ocean, 

 and these, falling to the bottom, provide abundant food for the rich deep-sea fauna, which, 

 we shall see, lives on the sea-bed in this region of the ocean. 



One of the most remarkable features of the meteorology of the globe is the low r 



