on Qiiartz Rock. 267 



constituted a portion of Schihallien and of the northern side of Glen 

 Lyon, terminating in the micaceous and chlorite schist of the ridge 

 of Ben Lawers. Taking it up now from Blair we shall find it 

 occupying a large proportion of the whole group of hills which lies 

 between the Bruer and the Tilt, lying over the granite and stretching 

 away towards Glen Dee, and thus uniting with that tract of it which 

 I also described last year as skirting the great granite mass of the 

 Grampians towards its eastern declivity. Returning again to Blair 

 it is found extending over the whole ridge of Ben Gloe, and here it 

 scarcely ever alternates with schist. From Ben Gloe it may be 

 traced over the Scarsough into Mar, forming at the same time Cairn 

 ree and a considerable extent of the hills which skirt Glen Fernat 

 and Strath Airdle to the eastward. From Mar it is then seen to 

 form a principal portion of the tract which bounds Glen Shee on 

 both sides, but further into the hills of Angus I have had no oppor- 

 tunity of following it. If the several spaces which I have described 

 here and in the former paper, be marked on the map, it will be seen 

 to occupy a very large portion of the country, and one which will 

 I doubt not be easily extended. I do not mean to lay it down as a 

 rule, (since the irregular position of this class of rocks is such that 

 they scarcely admit of any rule), but I think it will be found here 

 most abundant in the vicinity of the granite, while the micaceous 

 schist on the contrary lies at the greatest distance from it. A mine- 

 ralogical map of Scotland, a work as yet far distant, will probably 

 confirm the generality of this remark. 



I have but little to add to the particular description of the rock 

 and of its several varieties given in the above named paper, but 

 there are a few circumstances worthy of record. 



In Ben Gloe it is found incurvated and contorted in the manner 

 of micaceous schist, a proof that, like all the other schistose rocks 



