496 Sir Henri/ Howorth — Replies to Criticisms. 



V. — Mr. Hakker and Mr. Deeley on the Scandinavian Ice-Sheet. 

 By Sir Henry H. Howoeth, K.C.I.E., M.P., F.R.S., F.G.S. 



ME. DEELEY tells your readers that he has recently been to 

 the summit of Mont Blanc, and has been studying the 

 difference between neve and glacier ice. This is interesting; but 

 we thought that a great many people had done the same thing during 

 the last hundred years, and we thought that one of them, Forbes, 

 had studied the famous Mountain and the phenomenon in question 

 to good effect, not in a casual visit to the Alps, but in the course of 

 many years of patient labour. Among other things we also thought 

 he had shown that in a viscous body like ice, the slope of the upper 

 surface necessary to make it begin to move is the same as the slope 

 which would be required to induce motion in the ice if its bed were 

 inclined at an angle. He further collected considerable evidence to 

 show what the least angle is upon which ice will begin to move. 

 This is the slope, the least slope, available. It is nothing less than 

 astounding to me that anyone should venture to postulate a Scan- 

 dinavian ice-sheet in the North Sea until he had considered this 

 necessary factor, and how it would operate. 



The Scandinavian ice-sheet was, I believe, the invention of 

 Croll, who, sitting in his arm-chair and endowed with a brilliant 

 imagination, imposed upon sober science this extraordinary postu- 

 late. He did not dream of testing it by an examination of the 

 coasts of Norway, or even of Britain, but put it forward apparently 

 as a magnificent deduction. All deductions untested by experiment 

 are dangerous. Thus it came about that the great monster which is 

 said to have come from Norway, goodness knows by what mechanical 

 process, speedily dissolved away on the application of inductive 

 methods. Of course it still maintained its hold upon that section 

 of geologists who dogmatise in print a great deal about the Glacial 

 period before they have ever seen a glacier at work at all ; but I 

 am speaking of those who have studied the problem inductively. 

 First Mr. James Greikie, a disciple of Croll, was obliged to confess 

 that this ice-sheet, which is actually said to have advanced as far as 

 the hundred-fathom line in the Atlantic, and there presented a cliff 

 of ice like the Antarctic continent, never can have reached the Faroes, 

 which had an ice-sheet of their own. Next Messrs. Peach and Home 

 were constrained to admit that no traces of it of any kind occur in 

 the Orkneys, or in Eastern Scotland. They still maintained its 

 presence in the Shetlands ; however, this was upon evidence which 

 is somewhat extraordinary. I do not mean the evidence as to the 

 direction of the striation, which was so roughly handled by Mr. 

 Milne-Home, but I mean the evidence they adduce that the boulders 

 found on the islands are apparently all local ones, and that, contrary 

 to the deposits of glaciers, they diminish in number as we recede 

 from the matrix whence they were derived. 



If we cross the North Sea we have the converging evidence of 

 Bonney and Matthew Williams in the Lofodens, of Pettersen in 

 Central Norway, and, may I add, of Kjerulf, whose splendid map of 



