SCALP A. GEOLOGY. 429 



and even if it should be found by a more careful search, 

 it cannot, from the nature of the ground, be discovered 

 to a depth and with a clearness sufficient to determine 

 satisfactorily the only point for which that knowledge 

 would be valuable, namely, the relative position of the 

 sandstone and limestone. This is a point of considerable 

 importance in taking an extended view of the structure 

 of the west coast of Scotland. 



Near the limestone, the dip of the sandstone beds is 

 conformable to it, namely, north-westerly, the direction 

 of the elevated edges of the strata being here, as in the 

 sandstone of Sky, N. E. There is however in this part 

 of the island some difficulty in ascertaining the quantity 

 of the dip, as there is an appearance of fracture and 

 confusion in many places ; it is not however greater than 

 the general average so often mentioned, namely, from 

 twenty to forty degrees; and rather seems to approach 

 to the lower than to the higher angles. 



Proceeding for some distance to the north-west, the 

 inclination of the strata changes to the reverse, namely, 

 the south-east, the direction continuing the same;* but 

 it is not possible to discover the gradations by which this 

 reversal takes place, as, between the two, there is inter- 

 posed 2^ mass of syenite which introduces an obscurity 

 into the whole arrangement. The same cause prevents 

 us from tracing the steps by which the sandstone is once 

 more reversed to its original position ; which, recurring 

 somewhere about the middle of the island, is afterwards 

 continued in an uniform north -westeni dip to its furthest 

 extremity. The mineral characters of the beds do not 

 so materially differ from those which occur in Sky as 

 to require a very detailed notice. Such particulars are 

 indeed so often trifling in themselves and so little con- 

 ducive to the illustration of the science, that I have on 

 many other occasions been induced to omit them, even 



* pi-ate xrn. %. i. 



