228 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 16, 



Nor is the ascending order above the limestone to be seen in the 

 parish of Durness without the intervention of a great fault. For, 

 though the former section (fig. 6, p. 371, vol. xv.) is correct in 

 showing that the ilaglike rocks constituting the cliffs on which the 

 Old Bishop's Castle is placed are superior to the limestone, I did 

 not then show that the valley which separates the two rocks was 

 the line of a great dislocation. In truth, I had not sufficiently 

 examined, as I have now done, the rock of the bold northern pro- 

 montory of the Farrid or Far-out Head. 



That promontory was erroneously referred to the old gneiss in 

 my former memoir, on conclusions drawn from a hasty visit of my 

 friend Mr. Peach, who brought to me specimens from one part of 

 the headland which had a gneissose aspect. Detailed examination, 

 in company with Prof. Ramsay, has, however, convinced me that 

 the whole of this headland, from its northern extremity to the 

 Bishop's Castle, a distance of several miles, is composed of the over- 

 lying flaggy quartzo-micaceous series. Owing to the great fault 

 which trends along the Bay of Balnakeale, the quartzose beds, which 

 in other places unite the limestones with the overlying series, are 

 not visible, — the lowest strata apparent on the sands of Balnakeale 

 being hard, dark-grey, flaggy, micaceous sandstones, in parts having 

 a flat-bedded and somewhat gneissic aspect. These graduate up- 

 wards into beds which are less micaceous, and become in parts 

 white and siliceous, with a slight greenish tinge. The whole of 

 these beds dip to the east at angles from 15° to 20°. From their 

 utility, the white flagstones have been quarried to some extent, and 

 here and there exhibit very broad masses, one of which, called 

 " the good wife's flag," projects seawards for several yards from the 

 lofty summit of one of the headlands. These flagstones closely re- 

 semble those of Melniss on the west side of Loch Tongue, to which 

 I last year called attention ; and I now repeat that no geologist who 

 ever looked at them could connect them with the old or funda- 

 mental gneiss of the West Coast. 



Their relative position at Melniss, where they overlie a vast mass 

 of the micaceous quartzose rocks, as well as the quartzose rocks and 

 limestone of Eriboll, was dwelt upon last year. 



The geologist who wishes to convince himself of the manifest 

 distinction between these upper flaggy rocks and that fundamental 

 gneiss which is seen on the west side of the Kyle of Durness, or 

 that which extends from the hill of Keannabin on the east to the 

 headland of Rispond, will at once see the distinction by passing 

 from thence to the promontory of the Farrid Head, and specially by 

 examining its eastern cliffs. 



Although this broad distinction is obvious, it is no easy matter to 

 define with accuracy all the dislocations within the limited Durness 

 basin until the country be well mapped. My note-books contain 

 many details showing the curvatures, metamorphism, and breaks in 

 the strata ; and in no part of the district are these phenomena 

 more striking than in the limited tract of Sangoe Bay and its 

 northern and southern extremities below Durine Inn. There hard 



