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GLEN-DOC HART. 297 



the low country, as a long serrated ridge, to the 

 west of Ben-Vorlich and nearly as high,) the 

 porphyritic mica-slate assumes a deep reddish 

 tinge from the oxidation of the iron it contains. 



Beyond the district of Loch-Earn -head, we 

 travel still through mica- slate, in which we ob- 

 serve considerable variety, both of structure and 

 of ingredients. Its colour in general, is greenish- 

 grey, and its lustre shining, or even sometimes 

 approaching to splendent. 



In the course of a few miles, the valley of Glen- 

 Dochart opens to view. At this place, in compa- 

 ring the high level we have now reached, with that 

 of the hollows left behind, we are naturally led to 

 remark, that the whole ascent from Callender to 

 Killin, illustrates beautifully the doctrine of the 

 water, in the progress of its gradual diminution, 

 descending from higher to lower valleys, through 

 the mountain hollows, which it has formed. 



The first example is the course of the Teath. 

 This is traced to the vale of Balquhidder, of which, 

 the waters, at the eastern point of the oval bason 

 that incloses them, bending southward, fall into 

 the mountain-hollow, or ravine, which forms Loch- 

 Lubnaig. There they had evidently, at a former 

 period, been pent up \ but at length, forcing their 



