Yol. 57.] SILUKIAN [?j ROCKS IN POEFAESHIRE, ETC. 341 



newer rocks composing the lenticles here described; just as the 

 Lewisian gneiss has been forced over the Torridonian and Cambrian 

 rocks in the North-western Highlands. 



In the Southern Highland area, owing to the faintly marked 

 crystalline character of the older rocks, an apparent order of succes- 

 sion has been produced that is far more deceptive than is usually the 

 case in the Durness-Erribol area. Indeed, in the case of the North 

 Esk section I was at first completely deceived by it, and it was only 

 on mapping out the ground in minute detail that the deception was 

 exposed. 



Pig. 6. — Enlargement of a portion of fig. 5, p. SJfO. 



stream 



Scale: 20 inches = 1 mile. 

 Green Slates V//////M Greta Rock BB Jaspecs 



Margie Limesloae 



E^SHighlandSeries^^ Margie Series I '' ' ' . 'l 



[The complicated folding of the lenticle A of the Margie Series, seen in the 

 former map (fig. 5, p. 340) between the major and minor thrusts, is well 

 fihown in the above enlargement.] 



There is, moreover, another deception even more difficult to 

 detect. Owing to the slightly crystalline condition of the Highland 

 rocks we seem to see a perfectly gradual transition, through the 

 greatly crushed newer rocks of these lenticles into the highly 

 crystalline schists of the Southern Highlands. In reality, however, 

 no such transition exists. Under the microscope the clastic micas 

 can be recognized in nearly all the newer sedimentary rocks, even 

 when close to the thrust-plane. No such clastic micas have ever 

 been detected even in the least altered Highland rocks. 



The facts and inferences set forth in the foregoing pages have a 

 very important bearing on a matter of controversy. In the area here 



