ROCKS OF THE NORTHERN HIGHLANDS. 403 



Flags may crop out low down on the shore, or under water, from 

 beneath the Quartzite, and that the fragments have been thrown 

 up by the tremendous waves which operate with such energy along 

 this exposed coast. 



At Whitten Head the rock nearest the Caledonian is the Seamy 

 Quartzite. Fragments of the Annelidian variety are found lying 

 about ; but these towering precipices, rising absolutely vertical for 

 nearly 500 feet, forbid close investigation, though a good cragsman 

 might perhaps meet with some success. Something more might also 

 be done with boats ; but so heavy is the swell on these stormy shores 

 that little could be effected, save in exceptionally calm weather, such 

 as rarely occurs in the district. 



The region north of Hope Ferry is thus seen to confirm the clearer 

 sections further south, the upper division of the Quartzite being 

 regularly overlain by the lower. 



I claim, then, to have proved that the Assynt series is folded 

 back upon itself for a distance of several miles south of Heilem, and 

 to have shown it to be highly probable that the inversion occurs the 

 entire distance from Craig-na-faolin to Whitten Head, a distance 

 of nearly 12 miles. 



C. The Caledonian Gneiss brought over the inverted Assynt Series 

 by Earth-movements. 



Structure of Ben Arnaboll (756 ft.) (figs. 9 and 10). — Good 

 sections are exposed along the dip (W. to E.) and the strike (N. 

 to S.) — the former in the cliff south of the road from Heilem 

 to Hope ferry, the latter in the precipitous escarpment over- 

 hanging the valley which separates the hill from Druim-an- 

 tenigh. 



The dip-section (fig. 9) represents the gneiss clearly overlying the 

 Quartzite * for a breadth of over a quarter of a mile, the two series 



Fig. 9. — Section of the northern side of Ben Arnaboll. 



(Scale 4 inches to 1 mile.) 



e. w. 



°2 f 



being at first sight apparently conformable, dipping to S.S.E. A close 

 examination, however, shows that the conformity is not perfect. 

 in one place the gneiss dips down onto the quartzite at a higher 

 angle, and other beds of gneiss come into the angle between the 

 two. At another spot, further to the east, the gneiss does not keep 



* The baud of quartzite in contact with the gneiss is slightly altered (no. 99 

 p. 418). 



