38o THE GREAT ICE AGE 



The glaciers of Heard Island and Kerguelen have, no doubt, 

 been carrying down moraine material into the sea, and this is 

 certainly done on a still greater scale by those of the Antarctic 

 continent. This sends off bergs which fill the whole ocean 

 south of 60°, and float much farther north. Some of them have 

 been seen 2,000 feet long and 200 high, and though most of 

 the boulders they contain are necessarily concealed, yet masses 

 of rock, supposed to weigh many tons, have been seen on 

 them. The whole sea bottom off this continent, as far south 

 as 64°, consists of ^blue mud, with boulders and pebbles, some 

 of them glaciated, and farther north there is, as far as 47 

 degrees of latitude, a considerable percentage of drift material, 

 and this sometimes in depths of 1,950 fathoms. It is evident 

 that, if large areas of the southern hemisphere were elevated 

 into land, we should have phenomena to deal with not much 

 unlike those of North America at present. 



Perhaps no discussion carries with it more of warning to 

 geologists to exercise caution in framing theories than this of 

 the great ice age ; and if the collapse of extreme views on 

 this subject shall have the effect of inducing geologists to keep 

 within the limits of well-ascertained facts and sound induction, 

 to adhere to the Lyellian doctrine of modern causes to ex- 

 plain ancient phenomena, and to bear in mind that most great 

 effects involve not one cause, but many co-operating causes, it 

 may lead to consequences beneficial to science ; and so, emerg- 

 ing from the cold shadows of the continental glacier, we may 

 find ourselves in the sunshine of truth. 



References: — "Acadian Geology," ist ed., 1855; 4th ed., 1892. Ice- 

 bergs of Belle-Isle, and Glaciers of Mont Blanc, Canadian Naturalist, 

 1865. "Notes on Pleistocene of Canada," Montreal, 1871. Papers at 

 various dates in the Canadian Naturalist and Canadian Record of 

 Science. "The Ice Age in Canada," Montreal, 1893. Canadian Pleis- 

 tocene, London Geological Magazine, March, 1883. Flora of the 

 Pleistocene, Bulletin of Geological Society of America, vol. i., 1890, 

 p. 311, Dawson and Penhallow. 





