362 SUMMARY OF CAREER CHAP, xi 



basins have once been filled with ice, for roches 

 moutonndes occur round their margins and rise from 

 their bottoms. There can be no doubt also that the 

 ice which filled them was in motion, for the rocks that 

 enclose them are scored and polished, and the direc- 

 tion of the striae shows that the ice descended into 

 the basins at their upper end and ascended from them 

 at the lower. Ramsay went farther, and insisted that 

 the hollows themselves had actually been dug out by 

 the moving ice. I have myself no doubt that he was 

 essentially right in this contention. That there may 

 be difficulty in the universal application of his doctrine 

 will be readily admitted, and was fully recognised by 

 himself. He carefully guarded himself by the very 

 title of his original paper, * On the Glacial Origin of 

 Certain Lakes/ from being supposed to have one 

 explanation for all sheets of fresh water over the surface 

 of the globe. But that the lakes in glaciated regions 

 are connected in origin with the general denudation 

 of the regions in which they lie is a fact which few 

 geologists who have carefully mapped the rocks around 

 these water-basins will dispute. And the only agent 

 known to us to be capable of the kind of erosion which 

 would produce such basins is land-ice. On any other 

 hypothesis yet proposed the lake-basins are not only 

 unintelligible, but contradictory to all that is now well 

 ascertained regarding the progress of denudation and 

 the influence of geological structure upon topography. 

 In connection with Sir Andrew Ramsay's glacial 

 work, reference should be made here to his papers on 

 the evidence for the existence of ice in Palaeozoic time. 

 The Permian examples cited by him were certainly 

 striking, but the general feeling among geologists 

 seems to be that the evidence is not convincing. The 



