of Secular Changes of Climate. 101 



they probably consist of low dismembered land or of groups 

 of flat islands little elevated above sea-level, but all fused 

 together by one continuous sheet of ice. In fact, it seems 

 highly probable that a very large portion of the ice rests on 

 a surface which is under the sea-level. Victoria Land is, of 

 course, certainly elevated and mountainous, but the character 

 of the Antarctic icebergs shows that this state of things must 

 be the exception and not the rule in those regions. 



If this be the case, the antarctic ice is just in the condition 

 admitting of its being easily modified by warm currents from 

 equatorial regions. In fact at the very present day, as Dr. 

 Neumayer has shown, the slight southward deflections of the 

 warm westerly drift-current caused by the projecting land- 

 masses of Australia,, Africa^ and South America, cut notches 

 in the ice. When the southern winter solstice was in peri- 

 helion during the glacial epoch, it is probable that the greater 

 part of the ice then disappeared. 



In fact this is a result which w r ould be even still more likely 

 to occur were the views held by Sir Joseph Dalton Hooker 

 and some others as to the nature of the antarctic ice proved 

 to be correct. Sir Joseph 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 

 infest the ocean between lat. 50° and 70°. If this theory 

 of Sir Joseph's 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. 



I think, however, that the whole of that enormous sheet 

 from which the icebergs are derived must be resting on the 

 ground, although it is very likely, as has been shown on a 

 former occasion *, that a very large portion of it may be on 

 the sea-bottom. The weight of evidence seems to favour 

 the assumption that probably the greater part of the Antarctic 

 regions, as has just been stated, consists of low flat groups of 

 islands separated by broad and shallow seas which have all 

 become filled with solid ice. It is quite possible that the ice 

 filling these seas may have originated in pack-ice, which ulti- 

 mately became converted into a solid and continuous sheet by 

 * Phil. Mag. November 1883, p. 357. 



