ROCKS OP THE NORTHERN HIGHLANDS. 401 



dolomite of Camas-an-Duin, the strikes passing below the waters of 

 the bay ; and we know that the quartzite of Druim-an-tenigh is on 

 the strike of the quartzite of the ridge above Camas-an-Duin. The 

 northern section differs only in the apparent absence of the Brown 

 Flags and Salterella-grit. There is, however, a considerable breadth 

 of covered ground at the Heilem isthmus ; and as the Flags and 

 associated beds reappear on the strike further north, it is reasonable 

 to infer that they are present in the isthmus beneath the super- 

 ficial deposits. It is, however, possible that they may, in part 

 at least, have been crushed or faulted out. 



Section in the Ravine above the Free Church. — Following the 

 dark Dolomite at the west end of the Camas-an-Duin section along 

 the loch to the south, we find it overlain by the white variety, as in 

 Assynt. The dip gradually sinks to the horizontal. Then there is 

 sudden contortion and crush, and the dip changes to E.S.E., the 

 same inclination being continued as far as the Erriboll ferry. 

 Here I turned up the slope to the south-east, which is occupied by 

 dolomite up to about 400 ft. It is seen dipping south-easterly at a 

 moderate angle, and is, in the ravine above the church, overlain by 

 fossiliferous S alter ella-o^mYtzite and grit, succeeded by the Flags 

 (50 ft.) and the Annelidian Quartzite. The last is not more than 30 

 or 40 feet thick ; and as it is broken and squeezed, there is no doubt 

 that the Seamy Quartzite is faulted out against the Caledonian. 



A little further to the south the folding-back of the Dolomite is 

 very clearly seen. At first it dips easterly at a low angle ; then, 

 within a few yards, it is bent right up to the vertical, and thrown a 

 little over, the Salterella-grit, Brown Flags, and Quartzite cropping 

 out on the eastern side in regular sequence. 



Section above Ei^riboll House. — The Dolomite, with an easterly 

 dip, occupies the lower slopes from the loch upwards. It is over- 

 lain regularly by inverted Salter ella-grit and quartzite, Brown 

 Flags, and Quartzite, precisely as in the last section. 



The so-called " Upper Limestone " comes in here between the 

 Quartzite (inverted) and the gneiss of the Hope series. It is a mass 

 of dolomite about 100 yds. long and 50 ft. thick. The gneiss, where 

 it comes down to the Quartzite at each end, is contorted. These 

 facts strongly suggest that this mass is merely a wedge of dolomite 

 let down into the fault between quartzite and gneiss. 



It would be superfluous to multiply sections in this area. The 

 facts described are seen, with immaterial variations, wherever the 

 rocks are clearly exposed. Having visited the district in two 

 successive years, and traversed the ground over and over again, I can 

 unhesitatingly affirm that all along the steep slopes which overlook 

 the eastern side of Loch Erriboll between the north end of Druim- 

 an-tenigh and the road to Altnaharra, a distance of nearly three 

 miles on the strike, the members of the Assynt series, dipping 

 easterly in inverted order, are bent back upon the same series 

 dipping in the same direction and uninverted. 



Section at Craig -na-faolin. — lhave not examined the rocks on the 

 strike to the south-west of the Altnaharra road ; indeed the ground 



