BENBECULA. GEOLOGY. 117 



modification was predominant. In one instance only I 

 perceived a rock traversed by minutely ramifying veins 

 of trap, of a compact basaltic nature like those before 

 described. The hornblende schist which appears, in a 

 geological sense, to belong to this rock, is found in very 

 distinct forms, and a bed of it on the summit of Benbecula 

 hill abounds in garnets. Some specimens are also cha- 

 racterized by containing greenish foliated talc. 



The exception above noticed is the following. At the 

 entrance of Loch Kyleswiaveg are some islands composed 

 of a schistose rock of a very peculiar character. It appears 

 at first sight to be an intermixture of common blue argilla- 

 ceous schist with grains of quartz and compact felspar ; a 

 more minute examination proves it to be an irregular and 

 very anomalous compound. But as this rock forms an 

 important feature of the adjacent land of North Uist, and 

 will require to be more fully considered hereafter, I shall 

 defer any further notice of it at present ; remarking only, 

 that it may possibly occupy some more of the outstanding 

 islands, or skirt some of the shores which I could not 

 inspect. 



