﻿156 ME. E. BATTERSBY BAILEY OJS T [vol. lxxii, 



Scarba occurs in this island in the midst of the conglomeratic 

 beds east of the Scarba Fault. 



The Conglomeratic Group, as developed in Scarba and the 

 islands on the north, is of exactly the same type as in Jura and 

 Islay, but with the conglomeratic tendency more marked. While 

 much of the deposit consists of coarse pebbly quartzite, it is 

 common to find beds containing unrounded blocks of pebbly 

 quartzite, black slate, and limestone — some of them several feet 

 long. There are no igneous boulders such as are commonly met 

 with in the Portaskaig Conglomerate, and the equally charac- 

 teristic white dolomite-pebbles of the latter are also absent. 



(3/) Port Ellen Phyllites. 



East Islay. — The prevalent rock-type is silvery-grey sandy 

 phyllite and slate, with some beds of flagstone. Certain members 

 of the group are calcareous. The metamorphism is rather higher 

 than in Central Islay. 



The Port Ellen Phyllites are the seat of an extraordinary 

 number of epidiorite sills, probably in some measure repeated by 

 isoclinal folding. 



South-East Jura.— The Port Ellen Phyllites of South-East 

 Jura are, for the greater part, an extremely sandy set of grey 

 phyllites, associated with many sheared grey sandstones. Purer 

 phyllites occur in bands, especially in the eastern portion of the 

 exposures, where they are much invaded by epidiorite-sills. Many 

 of the rocks are slightly calcareous, and a few seams of limestone 

 have been noted. Layers of black slate or phyllite are inter- 

 calated in the western part of the group. 



(3 g) Lapliroaig and Ardmore Quartzites, 



A quartzitic group, to which the above title ruay be applied, 

 follows south-east of the Port Ellen Phyllites. Epidiorite-sills are 

 common throughout, while the south-eastward dip which is charac- 

 teristic of the Port Ellen district is maintained very uniformly. 



The first oncomings of the group are best described as fine- 

 grained ' poor ' quartzites ( l Laphroaig Quartz-Schists ' of the 

 Geological Survey Memoir on Islay, p. 28). They are so much 

 interbedded with phyllitic material, that it is probably impossible 

 to map them out consistently. 



The portion of the group cropping out farther east consists 

 largely of pebbly quartzite, as at Ardmore and in Texa, the island 

 south of Laphroaig. 



There is a bed of conglomerate on the western shore of Loch 

 an-t-Sailein (3 miles east-north-east of Laphroaig), and a few 

 little bands of dolomite are interbedded with the quartz-schists a 

 short distance inland on the eastern shore of the same. These 

 rocks lie west of the pebbly quartzites of Ardmore type. . 



