THEORY OF ORIGIN OF LAKES 361 



in his chain of argument, but he undoubtedly pro- 

 pounded a method whereby, if such questions are 

 capable of solution, they may most advantageously 

 be attempted. 



(3) It was in his researches among the traces of 

 ancient glaciers and ice-sheets that Sir Andrew accom- 

 plished his most original physiographical work. His 

 demonstration of the occurrence of evidence of two 

 glaciations in Wales was an important step in the 

 elucidation of the history of the Ice Age, for he showed 

 that after a general glaciation of the Welsh hills and 

 valleys, and the deposition of the drift upon them, a 

 later time came when the ice existed only as local 

 glaciers in the valleys among the higher mountains. 



But his name will be most widely known for his 

 theory of the Glacial Origin of certain Lake-basins. 

 This theory has been warmly attacked and as vigor- 

 ously defended. The contest regarding it still con- 

 tinues, though more than thirty years have passed 

 since it was published. This is not the place for a 

 review of the voluminous arguments that have been 

 adduced for and against the theory. If we look upon 

 the doctrine as promulgated by its author, and not in 

 the extravagant form in which it sometimes appears in 

 the hands of too zealous partisans, we must admit that 

 Ramsay was the first to call attention to the remark- 

 able fact that lakes are especially numerous in the 

 glaciated tracts of the northern hemisphere. Taking 

 the rock-basin lakes on which he based his doctrine of 

 glacial erosion, it is a fact that while they are prodigi- 

 ously abundant in glaciated tracts like the gneisses 

 of Canada, Scandinavia, Finland, and Scotland, they 

 either do not occur, or are excessively rare, outside of 

 ice- worn areas. It is likewise true that these rock- 



