Dr. Mac CutLOCH on Qjtartz Rock, 4^1 



member among them. In the former notices I have already in 

 some measure described its general aspect and connections, although 

 the limited extent of my researches prevented me at that time from 

 pronouncing decisively as to the latter. I am now, from more 

 recent observations, enabled to confirm the suppositions there made 

 'with regard to its place among the older rocks, and to add such a 

 further description of its mineralogical character as to include many 

 more varieties. I shall content myself with merely pointing out 

 its geographic situation in those places which I was prevented from 

 examining more particularly, in the hope that some future observer 

 may direct his attention to them, and ascertain that which I have 

 left undone. 



This rock may be seen in Mar accompanying the Dee during 

 part of its course through a country consisting of granite, followed 

 by the usual covering of micaceous and clay slate, a country even in 

 the Wernerian use of the term, primitive. It appears to be stratified, 

 but of its more immediate connexion with the schistus I can say 

 nothing, as I had no means of examining into It. Following the 

 military road which extends from Braemar to Tomantoule it may 

 be observed in various places, and appears to form the whole or 

 eonsiderable portions of the hills which, declining from the granite 

 ridge of Cairn Gorm, accompany the courses of the Don and 

 the Avon, and are principally constituted of different kinds of 

 schistus. Pursuing this line northwards, it occurs more sparingly, 

 but may still be occasionally observed, together with the schist, till 

 the hills decline into the plain country about Fochabers. I can pro- 

 duce no observations through any part of this course to prove that 

 it is a member of this class of schistose rocks ; but from its mine- 

 ralogical character and general appearance, and from the resemblance 

 which it bears to those quartz rocks whose connexions with the 



