Mineralogy of Sky. 61 



stances is often found in the same place, but their order can never 

 be ascertained, for, the cliffs rising to a height of 500 feet or more, 

 they are so far out of reach as to prevent us from forming an accurate 

 judgment respecting the individual parts. It is only by examining 

 the fallen specimens that we can ascertain the number of the varie- 

 ties in any spot. They seem to me greater from Loch Bracadale 

 to Loch Brittle than elsewhere, but possibly this opinion may only 

 have arisen from the greater facility which I experienced in examin- 

 ing this line of the coast. I have in several places attempted to count 

 the number of strata, and they seem to vary from eight or nine to 

 twelve, fifteen, or even more, but it is not easy to define their 

 boundaries at the distance from which they must be viewed. The 

 way in which the several beds decompose often adds a very remark- 

 able feature to the cliffs : some become scoriform, others moulder 

 into large cavernous shapes, while a third set fall to powder ; and 

 these various appearances, combined with the colours of the iron clay, 

 give to the whole that aspect of having undergone the action of fire, 

 which strikes a common observer even more forcibly than a geolo- 

 logical one. 



I must now proceed to describe the trap which forms the moun- 

 tains, and which is not entirely limited to the Cuchullin hills, since 

 it is found constituting a great portion of Blaven, as well as parts 

 of the hill of Glamich, and of others whose names cannot be ascer- 

 tained, but of which the predominant parts are syenite and clink- 

 stone. I have no means of defining their limits with greater accu- 

 racy, partly because there is no sufficient map, and partly because the 

 country is nearly impassable in many places, and in others quite 

 inaccessible. 



I have attempted to trace at the foot of Garsven, the southern- 

 most of the Cuchullin, the point where the stratified trap ceases and 



