488 THE LIFE OF JAMES D. FORBES. [CHAP. 



him to wander, with more than a tourist's curiosity, 

 among the glaciers of Switzerland ; which first suggested 

 to him the idea of working out, by accurate observation, 

 the real cause of glacier-motion, still, in his opinion, 

 undiscovered, and which brought him back, year after 

 year, to these great mountains, where he toiled with a 

 devotion that told at last upon his physical frame. 



' The lessons which he had laboriously ]earnt among 

 the living ice-rivers of the Alps bore fruit when he came 

 again to wander among the more mountainous regions of 

 his own country. In the year 1840 Agassiz had made 

 the startling announcement that the British Islands had 

 once been deeply buried under a vast mantle of snow 

 and ice, and that the traces of its seaward motion were 

 yet fresh and clear upon the sides of the countless valleys 

 among the uplands. Following up the observations of 

 the Swiss naturalist, Buckland and Lyell had pointed out 

 the former existence of glaciers in the Highlands and 

 other parts of the country. When, however, we look 

 back upon the early discussion of this subject, we are 

 forced to admit that conclusions were often based upon 

 very hasty and imperfect observation. In particular, 

 glacier-moraines were often recognized in places where 

 no geologist would now be able to find them. Much as 

 Forbes knew of the geological effects of ice, his natural 

 caution kept him from taking part in this discussion for 

 a time, until he was able to produce more accurately 

 determined data than had, in many cases at least, been 

 available. In the year 1845 he visited the Isle of Skye, 

 and his eye, already trained to recognize the traces of 

 vanished glaciers in Switzerland, was at once struck by 

 the identity of the forms assumed by the rocks at Loch 

 Scavaig with the rochcs moutonntes of the Alps. Further 

 investigation led him to obtain complete demonstration 

 of the former presence of a group of glaciers descending 

 from the rugged scarps of the Cuchullin Hills. He 

 walked over mountain and glen, filling in a rough 

 sketch-map of the glacier valleys as he went along, and 

 in December of the same year he read a narrative of his 



