OF LOCHABEl'w 17 



den change of appearance and colour, from an extremely green 

 transparency, to a pitchy blackness, to become all at once of 

 an apparently unfathomable depth. This circumstance, which 

 I remarked at a moment when I had not even a thought of 

 Glen Roy, struck me very forcibly. But I had afterwards oc- 

 casion to notice, during the remainder of the same tour, that 

 such was almost invariably the case with those lakes having 

 steep shores of the same description. In Loch Lochy, Loch 

 Oich, and Loch Ness, wherever the mountains rose from a 

 depth with a sudden acclivity, the same appearances presented 

 themselves. And what appeared more extraordinary, and 

 what I scarcely expected, in sailing down the salt-water lake 

 or arm of the sea called Loch Linnhe, from Fort William to- 

 wards Coran Ferry, we even found the same kind of shelf in 

 similar circumstances on its southern side, though on a larger 

 and ruder scale. Since that time, I have had occasion to make 

 the same remark, where the hills rise abruptly from Loch Awe, 

 Loch Lomond, Loch Tay, and almost every other Highland 

 lake that I have visited. Most of the mountain lakes of Swit- 

 zerland and Italy, having sides of the same precipitous de- 

 scription, are surrounded by the same shelving margin ; and, 

 amongst many others, the lakes of Nemi and Albano were 

 particularized to me by an intelligent friend, as being both of 

 this character *. But I wish it to be always understood, that 

 the foregoing illustrations, as well as the diagram to which 

 I have referred, are merely applicable to the formation of 

 a shelf on the steep side of a mountain, where, though it 

 may not be found so broad as in other places, it will al- 

 ways be more sharply marked than when the waves are 

 VOL. IX. p. I. c expended 



* Since this paper was presented to the Society, I have had an opportunity of 

 satisfying myself of the accuracy of this remark \vith regai-d to these lakes, as 

 well as of adding to the examples of this general fact, from my own personal ob- 

 servations on the lakes of Maggiore, Lygano, and Como, as well as in the upper 

 part of the Lake of Geneva, and several other continental lakes, having precipitous 

 shores. 



