IN THE NOBTH-WEST HIGHLANDS OF SCOTLAND. 



413 



Pig. 8. — Diagrammatic Section in West Face of Glasven, near Loch 

 Gamnheach, to show Minor Thrusts or reversed Faults, Major and 

 Maximum Thrusts. (Horizontal distance IJ mile.) 



t A t 



t, Minor, T, major, T', maximum thrusts. T^. Glencoul Thrust. 



4. Features characteristic of the Maximum Thrusts. 



There are certain features characteristic of these maximum 

 thrusts which ought to be enumerated before proceeding to describe 

 the geological structure of the line of complication. 



a. The outcrops of these maximum thrust-planes resemble the 

 boundary lines between unconformable formations, because (1) there 

 is always a complete discordance between the strata lying above and 

 below the planes of disruption, and (2) each successive thrust may be 

 overlapped in turn by the higher one. In other words, the Glencoul 

 Thrust-plane may he overlapped by the Ben-More Thrust-plane, and the 

 Moine Thrust-plane may overlap both these and all major and minor 

 thrusts, till the materials lying above it rest directly on the undisturbed 

 Silurian strata. A remarkable example of the latter phenomenon 

 will be described in the sequel as occurring at Craig-a-Knockan, 

 south of Elphin. 



b. By means of denudation, outliers of the materials lying above 

 these planes are formed. Perhaps the most extraordinary instances 

 are the two prominent outliers, resting on the limestone-plateau at 

 Inchnadamff, of Archaean rocks with Cambrian and Silurian strata, 

 separated by two circular faults from the underlying limestones I 



c. The planes of these powerful thrusts along which the materials 

 have been driven are not always inclined at low angles, indeed they 

 are frequently very irregular. In some cases the thrusts may be 

 inclined at a gentle angle to the horizon and may suddenly become 

 vertical. 



d. Owing to the movements of the strata from east to west and 

 also to the friction along the unyielding lower plane or " sole " of 

 the thrust, there was a tendency in the materials to fold over and 

 curve under, thus producing inversion of the beds. As a result of 



