70 GENERAL COMPARISON OF 



it is not here succeeded by the sandstone, it must be 

 recollected that this stratum is also frequently wanting 

 in that district. 



The limestone of the southern shore is presented in a 

 very unquestionable form, since, as in Morven, it is suc- 

 ceeded by sandstone including coal. Its peculiar characters, 

 and the absence of organic remains, offer no argument 

 against this view of its nature : as in similar circum- 



O ' 



stances, where trap rocks interfere, the same changes are 

 found to occur in the conchiferous limestones. The occur- 

 rence of coal is here peculiarly important, as it identifies 

 these strata with those of Morven, of which this sub- 

 stance forms in many places an integrant, though a small 

 portion.* 



The circumstances under which the calcareous sand- 

 stone occurs on the western shore of Mull, are such 

 that it is impossible to trace its connexions with the 

 strata of the eastern and southern shores. From this, 

 and from the deficiency of the calcareous strata which 

 ought to follow it in order of subjacence, it might be 

 questioned whether these arenaceous beds were the upper 

 portions of the same set of strata. This is however 

 rendered probable, partly by the identity of their compo- 

 sition with the sandstone of Morven, and partly by the 

 analogy of Rasay ; where, in a similar manner, the strata 

 above the lias, which resemble these, are found in contact 

 with the primary rocks ; the intermediate members being 

 absent. Should this be the case, it will appear that the 

 limestone has here also, as in Rasay, been extenuated 

 until it has vanished. That conclusion follows from the 

 structure of Inch Kenneth. It has been shown that in 



* The situation of this coal in Morven is on certain occasions very 

 remarkable, and capable indeed of startling a geologist nearly as much 

 as a coal surveyor, since it occurs on the summits of primary mountains 

 exceeding 2000 feet in elevation. The explanation of this appearance is 

 easily derived from the preceding statements, and it is also indicated in 

 the accompanying section. 



