78 Prof. Forbes on the Topography and Geology of the 



a want of success appears incredible, if the Doctor had been 

 at all serious in his intention ; but every one who has stu- 

 died his indisputably valuable work just cited, must perceive 

 that his favourite method of studying geology was from a 

 boat, and that of the interior even of Skye (which he so often 

 visited) he knew comparatively little. On every one of three 

 visits which I have made to Skye, opportunity was not awant- 

 ing for ascending the CuchuUins. 



The mountainous part of Skye, between Broadford and 

 Loch Brittle (a distance of eleven miles), comprises two very 

 distinct groups of hills, as distinct in arrangement and exter- 

 nal form as in geological composition. The group of the Red 

 Hills (to the east) is distinguished by rounded forms, consist- 

 ing of a group of dome-shaped masses crowded together, and 

 composed of a kind of syenite, in which felspar predominates. 

 The Cuchullin range constitutes a more connected chain of 

 craggy peaks, whose fantastic outlines, in certain positions, 

 may perhaps vie with any in the whole world. They may be 

 compared to those of the granite mountains of Dauphine ; 

 and one part, in particular, resembles the Montague de la 

 Grave, aptly likened, by M. Elie de Beaumont, to " a gigan- 

 tic nut-cracker, menacing heaven with its open jaws." This 

 group, as we shall see, is more compact and less straggling 

 than the other ; its colour too is in singular contrast, varying 

 from brown to deep green on the one side, to purple on the 

 other, particularly after rain. Its composition is principally 

 of hypersthene rock, which was discovered here by Dr Mac- 

 CuUoch, of which the excessive toughness, and its resistance 

 to every kind of external action, whether from violence or 

 from weather, gives much propriety to the name. The moun- 

 tain of Ben Blaven stands beyond the proper limit of the 

 CuchuUins, but in form, and evidently also in composition, it 

 must be classed with them. 



The appearance of the Eed hills, as first seen after pass- 

 ing the Kyles of Skye, recalls, in almost every detail, the 

 groups of Buys of Auvergne. The absence of craters does 

 not altogether destroy the analogy ; for such mountains as 

 Ben na Cailleach and Glamich may be perfectly compared to 

 the Puy de Dome which has no proper crater, and of which 



