86 Mr. J. Bryce on the Lignites and Altered Dolomites 



worked to some extent by driving an adit inwards on the line 

 of the dip, which is about 20° to the westward; but the work- 

 ings have been for some lime abandoned, and the inner and 

 lower portions are now full of water. 



The floor of the coal has been already described. The 

 roof is a peculiar rock. It consists of a base or paste of an 

 ochreous steatite, with imbedded round pieces of the same 

 substance, and may hence be called a pisolitic ochre; it is S^ 

 yards thick. The bed above this is of the same character ; 

 but the base feels less unctuous, and with the imbedded stea- 

 tite it contains also imbedded calcareous spar. The base 

 effervesces briskly with an acid; and hence we may call the 

 rock a calcareous amygdaloid. The upper portion of this bed, 

 to the thickness of a few inches only, is very hard, and has a 

 semivitreous appearance, and thus closely resembles a por- 

 phyry. In common with the trap above, and, indeed, all the 

 beds in this locality, it contains much disseminated iron. The 

 rest of the cliff" is occupied by greenstone, which is the same 

 as the lower bed resting on the sandstone. 



Another bed of lignite occurs on the opposite, or north- 

 west side of the trap district, overlooking Ascog Lake. Tl)e 

 coal dips to the interior of the area, that is, nearly south. It 

 is of about the same thickness, and is accompanied by beds of 

 steatite and red ochre, very similar to those above described ; 

 but the nature of the ground is such that a complete section 

 cannot be had, and the precise number, therefore, and order 

 of the beds cannot be exactly stated. The association, how- 

 ever, of the lignite with ochres and steatites here also is suffi- 

 ciently distinct, and it is even probable that these beds are 

 persistent throughout the whole of this district. It is to these 

 ochreous and steatitic beds that Dr. MacCulloch refers, when 

 he says that he " has met with no similar substance among the 

 numerous trap rocks examined in the course of the survey of 

 the western islands." He has not indeed described any such 

 strata; yet casual mention is made (vol. i. p. 376) of an iron- 

 clay and jaspery substance, forming extensive beds in the trap 

 of the cliffs of Talisker, in Skye — the same in which the lignite 

 also occurs — and that these are often variegated with red, 

 gray, and purple colours. No further description is given, 

 nor is the precise position of the coal mentioned, the cliffs 

 being very difficult of access. 



But even by such a brief notice the steatitic beds and varie- 

 gated ochres are easily recognised ; and though these charac- 

 ters are not very distinctly marked in the beds we have been 

 describing in Bute, yet they apply exactly to the red and va- 

 riegated ochres, which occur as members of the trap series of 



