OF THE 0T7TER HEBRIDES. 



Pig. 8. — Section of Till, Fincastle Road, North Harris. 



ISM. S.E. 



83: 



a. Till, showing rude arrangement of stones in lee of rock. 

 Depth of section 12 or 15 feet. 



ments dislodged from them and enclosed in the superincumbent till 

 streamed away in the same direction. A good example of this is 

 shown in the annexed sketch section (Fig. 9), taken from a pit on the 



Fig. 9. — Section of Till, Fincastle Road, North Harris, 



N.W. S.E. 



a. Till ; v. Yein of felspar rock in gneiss, fragments of which are seen 



lying to north-west, enclosed in till at vvv. 



Depth of section about 10 or 12 feet. 



side of the Fincastle Eoad. A similar well-marked example occurs 

 close to the landing-stage at the Tarbert, where the debris derived 

 from a vein of pink felspar-rock and beds of dark hornblendic gneiss 

 and schist are seen enclosed in the drift and streaming away from 

 the parent rocks in a westerly direction. Of course, in very many 

 places, the gneiss shows a firm and glaciated surface under the till, 

 and in such cases we do not expect to meet with the appearances 

 just described. 



The only rock- fragment in the till which I took to be probably a 

 stranger to the island was a hard blue calcareous greywacke or sili- 

 ceous limestone. No rock of this kind, as far as I know, occurs in 

 the Long Island, but it closely resembles some of the impure lime- 

 stones or calcareous greywackes associated with the Silurian limestones 

 of the Northern Highlands. A limestone occurs at Obbe, in Harris; 

 but the boulder referred to bears no resemblance to it. I detected 

 it in a pit on the Fincastle Eoad. Stones foreign to the island ap- 

 pear to be so entirely wanting in all the other exposures of till * 



* Of course it is quite possible that some of the till stones may have been 

 derived either from the bottom of the Minch or from the mainland, One meets 

 with occasional fragments of syenite, boulders of basalt are not very un- 

 common, and some of these may not belong to Harris ; but as basalt-dykes 

 occur in the island, and the gneiss is occasionally syenitic, we cannot cite these 

 boulders as strangers. 



