90 Prof. Forbes on the Topograph}/ and Geology of the 



described. In the heart of the chain at Loch Coruisk, the 

 veins are extensively parallel, and dip to the N. (at least so 

 I find it stated in my notes made on the spot), or more pro- 

 bably NW., forming, doubtless, a triple system of cleavage 

 to the two seen in Fig. 3, of which the vertical ones may be 

 considered as running parallel to the strike of the bed. 



These dykes aiford no conclusive evidence as to the rela- 

 tive age of the hypersthene and surrounding trap ; for, as 

 has been already said, they traverse both, though I do not 

 recollect to have seen one and the same vein pass the junc- 

 tion. A more critical phenomenon would be the occurrence 

 of a hypersthene vein in the surrounding trap. Such an oc- 

 currence is not recorded : but I believe that I have detected 

 such an one on the extreme north-eastern acclivity of the 

 Cuchullins, below the spur of rock of which I do not know 

 the name, but which bounds the Feu-na-Corry on the east. 

 It is unfortunately covered by vegetation ; but, as far as I 

 could make out, there is a dyke of hypersthene, 20 yards wide, 

 running through the syenite, and itself traversed by clay- 

 stone veins running NNW. I am not prepared, however, 

 to affirm positively so important a fact without a second 

 examination.* 



On the Traces of Ancient Glaciers in the Cuchullin Hills^ 



I cannot close this paper without referring to a class of 

 facts which have struck me more than almost any others 

 during my late survey ; I mean the evidence for the former 

 existence of glaciers in the mountains of Skye. Having 

 hitherto taken no share in the discussions raised as to the 

 proofs of glacial action in this country, and being as much 

 indisposed as ever to embark in a theory which offers such 

 evident difficulties, I yet feel it to be a duty to make known 

 what I have observed in connection with it among the Cu- 

 chullin Hills ; phenomena so singular and well marked as to 

 require a steady and patient consideration in whatever way 

 they may be attempted to be explained, and which I am com- 



* What Dr MacCulloch says on the subject of veins, may be found 

 in his Description, pp. 370, 386, 390. 



