ICE SHEETS AND GLACIERS 



quite actively on Mount Cook and Ruapehu which are 

 intersected by this layer. The lower sloping line (on 

 the right) shows where this nivation layer was situated 

 in Pleistocene times. It had in fact descended about 

 one thousand five hundred feet below its present posi- 

 tion, and cirques were being actively cut on Kosciusko 

 and Mount Field at that period. It will be noticed that 

 neither of these "layers" intersects the Antarctic 

 mountains. But we have a good deal of evidence 

 that world temperatures were warmer in Pliocene times 

 than they are to-day. It is possible, therefore, that 

 the cirques of Antarctica were cut several million years 

 ago, possibly during late Pliocene times. ^ At any rate 

 the cirques high on the slopes of Mount Lister have 

 a present-day temperature of —25° F. On no theory 

 of glacier erosion can the cirques be due to the tem- 

 perature or snowfall conditions obtaining there to-day. 



Classification of Glaciers 



There have been a number of different categories 

 proposed for the differing types of glaciers. It is 

 quite clear, as Hobbs has pointed out, that classes 

 which depended on knowledge gained in the European 

 Alps were quite unsatisfactory. The Mer de Glace 

 is merely the dwindling relic of one limb of the mighty 

 glacier which formerly filled the huge Chamonix Val- 

 ley. Hobbs in his book, Existing Glaciers, produced 

 a useful classification which took into account the 



3 See the writer's paper on this aspect of glaciation in Proceed- 

 ings of the Pan-Pacific Scientific Congress (Tokyo, 1926) ; with 

 five block diagrams. 



