The Scientific Advantages of an Antarctic Expedition. 435 



be cast by Antarctic exploration. Oceanic circulation ; meteorology ; 

 magnetism ; distribution of animal and vegetable life, not only in 

 tbe present but in the past ; geology ; mineralogy ; volcanic action 

 nnder special conditions — all of these are subjects on which the 

 phenomena of the Antarctic regions are sure to bear directly. 



If, however, I am asked to specify more particularly the question 

 on which I look for invaluable evidence which can be got nowhere 

 else, I must name, above all others, the most difficult questions 

 involved in quaternary geology. Geologists are nearly all agreed 

 that there has been, very recently, a glacial age — an age in which 

 glacial conditions prevailed over the whole northern hemisphere to 

 a much lower latitude than they prevail now. But geologists 

 differ widely and fundamentally from each other as to the form 

 which glacial agencies took during that period. In particular, many 

 geologists believe in what they call an " ice sheet" — that is to say,, 

 in the northern world having been covered by an enormous mass of 

 ice several thousand feet thick, which, as they assert, "flowed" over 

 mountain areas as well as over plains, and filled up the bed of seas 

 of a considerable depth. Other geologists disbelieve in this agency 

 altogether. They deny that even if such a body of ice ever existed, 

 it could possibly have moved in the way which the theory assumes. 

 They affirm, also, that the facts connected with glaciated surfaces 

 do not indicate the planing down by one universal sheet of 

 enormous weight and pressure; but, on the contrary, the action or 

 small and lighter bodies of ice, which have acted partially and un- 

 equally on different surfaces differently exposed. 



We might have hoped that this controversy could be settled by 

 the facts connected with the only enormous ice-sheet which exists 

 in the Northern Hemisphere, viz., that which covers the great con- 

 tinent of Greenland. But that ice-sheet, enormous though it be,, 

 does certainly not do what the ice-sheet of the Glacial Age is sup- 

 posed to have done. That is to say, it does not flow out from 

 Greenland, fill the adjacent seas, or override the opposite coasts, 

 even in so narrow a strait as Smith's Sound. But this evidence is 

 negative only. In the Antarctic continent we have reason tD believe 

 that there is a larger ice-sheet, and it certainly does protrude into 

 the adjacent seas, not merely by sending out vast floating frag- 

 ments, but in unbroken ice cliffs of great height. Now we want to 

 know exactly under what conditions this protrusion takes place. 

 Dr. Murray speaks of it as " creeping " seawards — a more cautious 

 word than " flowing." But is it certain that it does even creep ? 

 May it not simply grow by accretion or aggregation till it reaches a 

 depth of water so great as to break it off by floatation ? Does it, or 

 does it not, carry detritus when no detritus has been dropped on its 

 surface ? Or does it pick up detritus from its own bed ? Or does 



