212 DISCUSSIONS IN CLIMATOLOGY. 



merchant ships for one vessel belonging to the Navy. 

 And perhaps not one out of every ten thousand mer- 

 chantmen has ever fallen in with one of the great 

 ice islands we now speak of. 



The testimony from icebergs may therefore be 

 regarded as decisive against the opinion that the 

 Antarctic ice cannot be more than 1400 feet thick. 



That 1000 or 2000 feet cannot be the limits of 

 thickness attained by continental ice is amply proved 

 by the geological evidence, which goes to show that 

 during the Glacial Epoch the ice in some places much 

 exceeded 1400 feet. Professor Dana has proved 

 that during the period in question the thickness 

 of the ice on the American continent must in many 

 places have been considerably above a mile. He has 

 shown, that over the northern border of New England, 

 the ice had a mean thickness of 6500 feet, while its 

 mean thickness over the Canada water-shed, between 

 St. Lawrence and Hudson's Bay, was not less than 

 12,000 feet, or upwards of 2 J miles.* Professor 

 Erdmann and Mr. Amund Helland have shown that 

 the ice in some parts of Scandinavia was at least 6000 

 feet thick. It has been proved by M. Guyot and others, 

 that the great valley of Switzerland was formerly 

 filled with a mass of ice between 2000 and 3000 feet 

 in thickness. Mr. Jamieson found that the isolated 

 mountain of Schiehallion, in Perthshire, 3500 feet high, 

 is marked near its top as well as on its flanks, and this 

 not by ice flowing down the side of the hill itself, but 

 by ice passing over it from the north. Dr. James 

 Geikie has shown -j* that the ice between the mainland 

 and the Outer Hebrides was as much as 3700 feet in 

 thickness. The great mass of ice from Scandinavia, 



* See "American Journal of Science and Arts," March, 1873. 

 f " Quart. Journ. Geol. Soc," vol. xxxiv., p. 861. 



