MULL. GEOLOGY. 573 



I need not add to the few remarks already made on the 

 versatile outline of the trap rocks. Instances of diversity 

 which do not require enumeration, are known to all those 

 who have examined this country with the eye of an artist 

 and the hammer of a geologist. It is enough to have 

 pointed out the fallacy of the rule as a caution to the 

 observer ; who should convince himself, if he is not 

 already convinced, that he can be certain of nothing 

 which he has not touched. But to return to the descrip- 

 tion of the trap which forms the southern district of 

 Mull. 



The most striking of the exposed rocks in this part of 

 the island, are those which form the high cliffs of the 

 southern shore and stretch in a mural line from Inimore 

 towards Loch Speliv. These are of considerable altitude, 

 as already noticed, varying apparently from 300 to 600 feet. 

 Most of the various forms of trap, and, among others, 

 the columnar, are to be seen ranging along the cliffs in 

 a stratified disposition, incumbent, and occasionally al- 

 ternating, as already mentioned, with the secondary 

 strata. In passing Loch Buy towards the east, the alti- 

 tude of these cliffs diminishes, and at length gradually 

 subsides into the low shores which extend from Loch 

 Don to Duart bay, and beyond that towards Scallasdale. 

 Throughout this latter tract the external character of the 

 rock is changed, but I need add nothing to that which 

 has already been said respecting it. I may merely remark 

 that the hardest kinds contain abundant amygdaloidal no- 

 dules of the different zeolites ; substances in general much 

 less frequent in the hard than in the soft varieties of this 

 extensive family. 



Every geologist who is familiar with countries formed 

 of stratified trap, must have been struck with the general 

 horizontality and evenness of the strata that enter into 

 their composition. This is remarkable in Sky ; it is even 

 more so in Mull, where high mountains, as those of Gribon 

 may be called, are formed by the repeated superposition 



