302 Dr. Mac Culloch on the Geology ofGkn Tilt, 



minute, but well crystallized and dispersed throughout the stone. 

 It is by no means uncommon in similar rocks in Scotland, and oc- 

 curs, among other places, in Cri.fFel as well as in Braemar ; and I 

 may here add, that I have found it in specimens of Egyptian gra- 

 nite which contained no hornblende. I think it unnecessary to 

 enter into any further details of this nature. 



It is not far from the granite which I have now described, that 

 the quartz rock with the transition into granite which I have 

 already described, occurs, and it is not necessary to make any 

 further observations on it in this place. At Craig Crocha the gra- 

 nite again makes its appearance ; and here, as in other places, it 

 passes by a gentle gradation into syenitic granite, that is, it con- 

 tains crystals of hornblende. 



It is quite superfluous to continue the details of the structure of 

 this ridge with the same minute accuracy, a* they will be found 

 little else but a repetition of those which have preceded. It 

 is not however the less important to give a general vieM, of the 

 whole, and I shall therefore state it to as wide a range as is ne- 

 cessary for understanding the structure of Glen Tilt, and the true 

 nature of the interesting appearances there visible. 



Ben Dearg may properly be considered as the most conspicuous 

 portion of the granite which forms the basis of this range of hills. It 

 is connected with the right ridge of Glen Tilt which I have now 

 beea describing, by a succession of granite and quartz rock, exactly 

 similar to that already noticed. Pursuing the direction of the country 

 across the Tarflf to Cairnmuir and the head of Dee, the same succes- 

 sion gradually unites the granite of this tract to that which forms 

 Cairngorm and Ben Avon, the great central granite of the Grampiaa 

 hills, and the most extensive tract of thrSrock in Scotland. 



There is no reason then to doubt that the granite which forms the 



