266 Dr. Mac Culloch's Supplementary Observations 



to the neighbouring shepherds, who, still mindful of their ancient 

 allegiance, show the spot where, among many others, the unfortunate 

 Prince was for a time concealed. The minuter fragments of quartz 

 rock and granite have here formed themselves into angular conglo- 

 merates, which are in some instances perfectly compact, the smaller 

 cavities having been filled up by siliceous matter, while the larger 

 fragments, touching only by small surfaces, have left considerable 

 openings between them. Here then we have an example of a 

 breccia formed in times comparatively recent. The conglomeration 

 of the fragments is not the effect of the accidental presence of ironj 

 so commonly the cement of modern breccias, but is evidently the 

 result of a deposition of siliceous matter. This could only have 

 been brought into solution by the rains, or by the operation of com- 

 mon water, since the stones are out of the reach of other causes, 

 and it serves to prove that the -solution of silica in water, a circum- 

 stance which some have supposed limited to the ancient state of the 

 Globe, is a process still going on. I have indeed noticed in the 

 former remarks on quartz rock the same fact as proved by the ena- 

 melled and polished surface which its exposed parts so often assume. 

 We have no means from historical record of determining the anti- 

 quity of this slide , but as far as any conjectural evidence can be 

 adduced from the little accumulation of soil which has formed on 

 the horizontal surfaces, and the bare aspect of the faces, on which 

 scarcely a lichen has yet planted itself, it cannot be of very high 

 antiquity. The observation is further of importance as illustrating 

 the origin of the brecciated jaspers, as well as that of the other 

 breccias formed of angular fragments. 



From Loch Ericht the quartz rock branches away to the moun- 

 tains that skirt Ben Nevis and Glenco, as I noticed in the above 

 mentioned paper. I have already observed in that paper that it 



