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EECEXT WORK OP THE GEOLOGICAL SUEVET 



This powerful thrust can be traced northwards to the Chalda burn 

 and southwards across the Poll an Droighinn and Traligill burns to 

 the great plateau east of Stronechrubie. Following the line of 



Yig. 14. Horizontal Section from Loch Assynt, across the Silurian 



Limestones, to Cnoc an Droighinn. (About | mile in length.) 



crroe ah droichinm 



section east to Cnoc an Droighinn, various subdivisions of both the 

 lowest limestone groups with their dykes are repeated by reversed 

 faults, till they are overlapped by the " pipe-rock " above the Glencoul 

 Thrust-plane. 



Between Ardvreck Castle and Achumore the relations of the 

 strata are still more complicated. Briefly stated, the principles 

 involved in the structure are as follows : — (1) the occurrence of a 

 series of major thrusts running roughly parallel with each other, 

 producing great horizontal displacement ; (2) the piling up of the 

 limestones along the planes of these thrusts by minor reversed 

 faults ; (3) the subsequent arrangement of the strata in a series 

 of gentle arches and troughs, the axes of the folds heing quite 

 inclepenclent of the trend of the major thrust-planes. 



Precisely the same principles are illustrated in the broad plateau 

 east of Stronechrubie. The first great major thrust in the limestone 

 is well seen in dip-section in the great cliff about half a mile south 

 of the Inchnadamff Hotel, where it drives forward the Eilean Dubh 

 limestones, the latter dipping at a high angle to the plane. Again, 

 on the slope south of the Traligill burn at Glenbain about six 

 major thrusts are admirably seen in dip-section, the beds between 

 these planes being piled up by minor reversed faults. Occasionally 

 outliers of the " Pucoid-beds "' and Serpulite-grit are found, capping 

 the Eilean Dubh limestones in the north-east part of the plateau, se- 

 parated from each other by major thrusts. But subsequent to these 

 various displacements driving the strata together, the area along 

 the north-eastern and eastern margins of the limestone-plateau was 

 elevated in the form of a great dome ; and hence we find, at inter- 

 vals, various sections showing the natural passage from the " pipe- 

 rock " to the "Pucoid-beds," Serpulite-grit, and basal limestones, the 

 strata being inclined towards the west. This feature has given rise 

 to the belief, advocated by several observers, that the limestones 

 were arranged in a great synclinal fold. But the examination of 

 the great quartzite range of Braebag, to the east of the limestone 

 plateau, points to the conclusion that the quartzites were piled on 

 each other by numerous thrusts prior to the formation of the great 



