102 



dikes common to both granites, and newer than either of them ; and 

 a confirmation of the view already stated (Art. 46), that trap, and 

 not the fine-grained granite, is the newest rock in the island. It 

 seems highly probable, from the direction in which these and the 

 other dikes already mentioned range, that they are the same as 

 those which were found crossing the fine-grained granite tract on 

 the west side of the lorsa valley (Art. 46, p. 68). 



68. The jagged and notched character of the ridge makes it im- 

 possible for us to pass along it on our way to Cior-Mhor ; neither can 

 we safely cross the huge granite slabs at the back of the ridge, as 

 they are smooth, slippery, and considerably inclined. But below 

 these a safe, though rough and irregular pathway, will be found ; 

 and from this we can occasionally pass upwards towards the ridge, 

 along the clefts in which the dikes lie, to have a peep down into 

 Glen Rosa, or to scan the frowning cliffs on the north side of Ben- 

 Talshan. For the latter purpose a telescope will be useful. We 

 must be careful, however, to return by the cleft by which we came 

 up, till we reach the path. The granite sheets must not be attempted, 

 as a single false step upon them might hurl the tourist with fearful 

 velocity into the valley at their base, filled with blocks and debris. 

 The range, width, and structure of the dikes are well seen as we 

 pass along ; the width is various, in some 5 or 6 feet only, in others 

 10 to 12, and 15 to 18 feet. The broadest, being of this latter 

 width, is one on the south side of the col, between Glen Eosa and 

 Glen lorsa. It consists of a crumbling greenstone, and ranges 

 29 W. of N. The others have various ranges between W. 

 and N. Many small shining flakes of crystalline oxide of iron occur 

 in the trap of these dikes. The ridge of the Ceims is composed of 

 the coarse-grained granite ; but the path at its west base, along 

 which we have come, is partly on the fine-grained variety. This 

 appears generally at the height of about 1,600 feet on the cols, and 

 on the west side of the ridge, but is not seen in Glen Eosa nor on 

 Goatfell. It disappears on the ascent of Cior-Mhor, and is suc- 

 ceeded by the coarse-grained variety. The contrast is remark- 

 able. The rock has quite a different aspect, a different feel under 

 the hammer, and a peculiar style of disintegration, giving smooth 

 outlines, and an entire absence of the aiguille-like highly pic- 

 turesque forms, into which the coarse variety is resolved by the 

 action of the atmosphere. The decomposition of both rocks conceals 

 the contact, and we were not so fortunate as to discover anywhere 

 the actual junction of the two varieties. But the day is waning, 

 and we have yet to scale the lofty peak of Cior-Mhor, shooting 



