258 PEOFESSOE JAMES GEIKIE, LL.D., D.C.L., F.E.S., ETC., ON 



question I have been discussing. The valleys were hollowed out 

 by running water when the land stood 3,000 to 4,000 feet higher 

 than now. Their excavation must necessarily have occupied a 

 prodigious time, yet throughout that protracted period, rivers and 

 not glaciers were their occupants. Clearly, then, if the fiord- 

 valleys were excavated in late Pliocene and early Pleistocene times 

 the land had then all the elevation required by Mr. Upham for the 

 production of great ice-sheets, and yet no general glaciation took 

 place until the hollowing out of the valleys had been practically 

 completed. All that the glaciers have done has been to grind out 

 hollows in the bottoms of the valleys, and to modify the general 

 contour of the ground. 



