POLAR ICE NOT DUE TO ELEVATION. 75 



the larger portion of the sheet rested on the bed of 

 the Baltic, German Ocean, and the seas around Great 

 Britain and Ireland and the Orkney and Shetland 

 islands. That the Antarctic ice was formed on low 

 and flat land, bordered for considerable distances by 

 shoal water, was the opinion also of Sir Wyville 

 Thomson. 



Sir Joseph Dalton Hooker thinks that much of the 

 Antarctic ice-sheet, thousands of feet in thickness as 

 it is, was formed by the successive accumulations of 

 snow year by year on pack-ice. The snowfall in the 

 Antarctic regions he believes to be enormous both 

 during summer and winter; and as but a very small 

 portion of it melts, the accumulated snow is perfectly 

 sufficient to form such a sheet. He does not consider 

 that there is land enough in the south-polar area to 

 supply the astounding number and gigantic size of the 

 icebergs that float in the ocean between lat. 50° and 70°. 

 If this theory be correct, and immense masses of the 

 ice are really afloat, we can easily understand how 

 the whole might, during a southern interglacial period, 

 be broken up, dispersed, and melted by an inflow of 

 equatorial water. 



It is quite possible that the ice filling these seas may 

 have originated in pack-ice, which ultimately became 

 converted into a solid and continuous sheet by long- 

 ages of successive snowfalls. As layer after layer, 

 converted into ice, was being heaped upon it year by 

 year, the mass would gradually sink until it rested on 

 the sea-bottom* After this it would assume all the 

 characteristics of continental ice. 



* In this opinion I am glad to find that Sir Joseph to a certain 

 extent concurs, for in a letter to me on the subject he says: — "I 

 cannot doubt but that the icebergs have originated from the ice of 

 the great southern barrier ; and what I suspect is, that much of this 



