Fearnsides, Elles, Smith — Talceozolc Rocks of Fomeroy. 115 



relation now remains undisturbed is a matter open to doubt. In the 

 district south-east of Craig Bardahessiagh, we believe that it is main- 

 tained ; but in the western areas it would seem that the Bardahessiagh 

 beds were involved with the rest, were faulted in addition to being 

 folded, and have been driven forward along the depression deter- 

 mined by the Pre-Silurian outcrop of hornblendic rocks. In this 

 western district, also, as about Lough Bracken, and perhaps further to 

 the north, small areas of Graptolite-bearing shaly drift seem to indicate 

 the former existence of detached patches of true Silurian rocks, which, 

 in the absence of any representative of the Desertcreat rocks once 

 underlying them, must have been thrust forward in advance of the 

 latter, and so have rested directly on the hornblendic rocks. In this 

 connexion it is interesting to note that such faulted shale patches 

 occur only upon the Hornblende schist areas, which, from their 

 nature, determined the existence of hollows in the surface topography 

 in Ashgillian times, as well as at the present day ; it may therefore be 

 inferred that a topography, somewhat resembling that at present 

 characterizing the crystalline schist area to the north, dates back to 

 Pre-Silurian times. 



Of faulting unassociated with folding we have little evidence ; all 

 the faults observed seem only to occupy the place of the middle limb 

 of an unusually sharp isoclinal fold. The most striking example of this 

 is the overthrust fault, which follows, and to some extent determines, 

 the course of the Little River from our most easterly exposures, up 

 to and beyond the MuUagnabuoyah farm. This fault seems to be 

 the result of the breaking-away of a fold somewhat larger than the 

 others, and hading almost horizontally with a slight southern dip, 

 brings up older beds, and allows them to transgress over two or 

 possibly three of the northern synclines. The beds over which 

 the older beds have been pushed are crumpled up into little folds a 

 foot or two in amplitude. Quite near the fault the secondary folds 

 become overturned ; and some of the beds take on the appearance of a 

 slate, showing false cleavage or pseudo-stromatism, as viewed under the 

 microscope. Other small faults similar in character are comparatively 

 unimportant, and need not be further discussed here. 



As to the age of the folding we have little evidence ; but such as 

 we have points to the conclusion that it is at least to some extent 

 Post-Devonian. The Dingle beds appear to share the folding of the 

 older beds, though so brittle that faults often replace folds of the latter; 

 and it is possible that all the folding, as now seen, belongs to the same 

 period, though the existence of an unconformity at the base of the 



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