various parts of Scotland. 447 



point in various places round by the east coast to Troup Head. It 

 is visible at the pass of Aberfoyle, and possesses a character and 

 situation similar to that which it exhibits at Drymen. 



A ridge, parallel to that of Ben Lomond, is separated from it by 

 the valley which includes the Forth. A second parallel valley con- 

 tains Loch Ard and Loch Chon, which pour into the Forth at Aber- 

 foyle a tributary stream of equal magnitude. To the east this is 

 again bounded by a second ridge, nearly parallel to the first, of 

 ■which Ben Venn is the principal elevation. The valley which lies 

 at the foot of this ridge, contains Loch Ketterin, having for its 

 eastern boundary a double ridge, of which Ben Ledi is the chief 

 eminence. These four ridges appear to ramify from a central point, 

 situated between the top of Loch Ketterin and that of Loch Lomond. 



The whole of this country has been supposed to be of the same 

 formation as Ben Lomond, namely micaceous schistus, a suppo- 

 sition which I have found to be groundless. I am ignorant of the 

 nature of the ridge which separates the vale of Loch Ard from that 

 of the Forth, the nearest in order to the ridge of Ben Lomond. 

 But on examining the vale of Aberfoyle, as far as from the breccia 

 to the bottom of Loch Chon, I found it to consist of alternations of 

 graywacke, and graywacke slate, with clay slate, similar to those I 

 have described as occurring at Crinan, and placed with equal ir- 

 regularity of alternation. The beds are also elevated to high angles, 

 but I believe that the positions are various. In traversing the ridge 

 which separates Loch Ard from Loch Ketterin, the same rocks 

 appear, and quarries of fine roofing clay slate are wrought in various 

 parts of it. These, I believe, are of the same class, and belong to 

 the transition clay slates, but the whole ridge is so extensive and 

 broken, that it is extremely difficult, if not impossible, to obtain 

 access to it, except in a few places. On reaching the shores of LocH 



