THE GREAT ICE AGE 379 



sphere is at present emphatically the ocean hemisphere ; the 

 northern, the land hemisphere. Perhaps these conditions may 

 be capable of being reversed, in which case the periods of de- 

 pression in the south may have corresponded with those of 

 elevation in the north. One thing which we know is, that 

 there is a polar ice ring, not an ice cap, for we do not know 

 what is within its edges at the South Pole, about 2,000 miles in 

 diameter, and this in the only circumstances in which it can 

 exist, namely, surrounded by a vast ocean furnishing it with 

 abundant aqueous vapour. We also know that from this ice 

 ring radiate glaciers, carrying debris^ with which the sea bottom 

 is strown half way to the equator. If continents were elevated 

 out of the Southern Ocean, we should probably have on their 

 surfaces glacial deposits more widespread and continuous than 

 any remaining on the continents of the northern hemisphere, and 

 like some of them thinning out to a terminal edge or border, 

 instead of a terminal moraine like that of a glacier. ^ Thus we 

 may say wth some truth that the southern hemisphere is now 

 passing through one phase of the Glacial period. 



I have often thought that in the southern hemisphere the 

 condition of Kerguelen Island and Heard Island, as described 

 in the reports of the Challenger,^ must very nearly represent the 

 state of some mountain ranges and peaks in North America 

 in the Glacial age. Heard Island, in S. latitude 53° 2', is a 

 mountain peak 6,000 feet high, and 25 miles in length. It 

 sends down large glaciers to the sea. In its larger neighbour, 

 Kerguelen, the glaciers do not reach the sea ; but there is evi- 

 dence that at one time they did. It is still more curious that, 

 m Kerguelen the modern ice overlies late tertiary deposits, 

 holding remains of large trees, indicating a more continental 

 condition and mild climate at no very remote period. 



* This is now admitted by Chamberlain and others to be the case with 

 the oldest boulder clay on the American continent. 

 ' Vol. i. p. 370, etc. 



