GARVELOCH ISLES. GEOLOGY. l6l 



any conjectures which might be offered respecting those 

 next in order, to the description of Isla, where the same 

 series occurs ; each place mutually throwing light on the 

 other. 



It only remains to mention the possible uses of this 

 limestone as an ornamental substance* 



The basis of the breccia is commonly of a slate blue 

 colour verging to purple, and is mottled or sprinkled with 

 the white or red spots derived from the calcareous matter ; 

 while the imbedded fragments being white, yellow, and 

 pink, a very ornamental marble is the result. It is 

 little if at all inferior to many of the Italian, or antique 

 breccias of popular celebrity. The veined specimens of 

 the simple limestone are, with a different character, equally 

 ornamental ; and, according to the direction in which the 

 veins are cut, produce varieties resembling in disposition 

 the well known marble of Sienna ; but differing from it in 

 colour, inasmuch as pink and dark red occupy the place of 

 yellow and brown. 



To these remarks I have only to add, that cubical 

 pyrites occurs in the schistose rocks, and that I found 

 a detached fragment of siliceous compact hematite ; pro- 

 bably a nodule detached from the conglomerate. 



As an appendage to this article it is proper to mention two 

 islands which bear the same name and lie between these 

 and Lunga ; Garveloch na skian and Garveloch na more. 

 They both resemble Lunga in composition, consisting of 

 quartz rock ; one of them being very conspicuous for a 

 large erect vein of white quartz resembling, at a distance, 

 the sail of a ship. 



VOL. II. M 



