438 Dr. Mac Culloch on the Geology of 



Loch Lomond, 



The formation of a new road on the bank?, of this lake, has ex- 

 hibited some instances of the contortions of mica slate, which are 

 deserving of notice, I have attempted to give a notion of them 

 in the accompanying sketches (Pl. 31. fig. 1, 2. — PI. 31f, fig. 3.) 

 as it is not possible to procure specimens of the magnitude requi- 

 site for that purpose. 



It would be superfluous to add any thing to the observations on 

 the inflexion of strata, in the " Illustrations of the Huttonian theory," 

 where this subject is ably treated. But as they consist chiefly of re- 

 marks on the continuous inflexions of extensive strata, it will not be 

 useless to notice the more complicated curvatures which take place In 

 the smaller masses. In a brief notice on certain waving lines of colour 

 occurring in killas at Plymouth Dock, transmitted last year to the 

 Society, I suggested the difl^iculties which attended a solution of this 

 question, the disposition of the colour having no relation to the 

 lamiurT of the schist. But in the contortions of the mica slate, the 

 laminse themselves are waved, and we have only therefore to enquire 

 into the conditions requisite to the production of this appearance. 



It is evident on inspection of the sketches, and will be equally so 

 to those who shall inspect the rocks themselves, that, if the several 

 laminge which compose any given mass, were to be now rendered 

 flexible, they could not be reduced to continuous straight lines, 

 without materially changing the relations of their several lengths, and 

 thus altering the figures of the rocks which now contain them. 

 It is therefore evident, that no general force acting on a large mass 

 has been the cause of these curvatures, but that they have been pro- 

 duced by the application of numerous partial forces acting on different 

 parts, and capable of stretching those sets of lamina: on which the 



