LU1NG. GEOLOGY. 137 



elevations varying considerably, but generally, as far as I 

 could perceive, occupying high angles, namely, from fifty 

 to eighty degrees. In some places nevertheless, and par- 

 ticularly on the eastern shore, they diminish, and the 

 angles of twenty, thirty, and forty degrees, very com- 

 monly found in this group of islands, become the pre- 

 vailing. 



The mass of this island consists of clay slate, exactly 

 similar to that of Seil and of Kerrera ; being an obvious 

 prolongation of the beds that constitute the former. It 

 is unnecessary to enter into its mineral description 

 except where any peculiarities occur : these will be 

 noticed here ; many of the appearances equally common 

 to Seil having been referred to this place, on account of 

 their greater conspicuity or facility of access. But it is 

 first necessary to point out the alternations of the strata 

 as far as any differences are found in them. 



The westernmost, and therefore the lowest rocks, consist 

 of the clay slate already described, alternating with the 

 same sandy schist and graywacke already mentioned in. 

 Seil, and disposed in a manner so perfectly similar that the 

 one is a mere repetition of the other ; it should rather 

 be said that they are but different portions of one line 

 of strata. If the line of grey rock, which, in Seil, follows 

 next to the western portion of the slate in the order of 

 superposition, be also prolonged, it will be found equally 

 to follow the clay slate in Luing ; rising into that ridge 

 which forms the most considerable elevation in the 

 island.* 



The external aspect of this rock, the mode of weathering, 



* On the highest part of this ridge, the remains of one of those forts 

 commonly considered of Danish origin are still to be seen, and in a state 

 of tolerahle integrity as far as its figure is concerned; the walls having 

 only subsided into a ridge of loose stones, It is of an elliptical figure, 

 about twenty yards by fifteen in its relative diameters, and, from the large 

 quantity of materials in the work, the walls must have been of con- 

 siderable thickness. 



