﻿132 



ME. E. BATTEESBY BAILEY ON 



[vol. lxxii, 



8. The I slat Anticline (Inneb Hebeides). By Eb-waed 

 Batteesbt Bailey, M.C., B.A., F.G-.S., Lieut. R.G.A. 

 (Read January 5th, 1916.) 



[Plate XII — Geological Map.] 



Contents. 



Page 



I. Introduction 132 



II. Detailed Descriptions 135 



(1) Geology of Colonsay and Islay, West of the Loch Sker- 



rols Thrust 135 



(2) The Loch Skerrols Thrust 139 



(3) Rocks above the Loch Skerrols Thrust, as far East as 



Luing .* 140 



(3 a) Maol an Fhithich Quartzite 140 



(3 b) Mull of Oa Phyllites 140 



(3 c) Islay Limestone 141 



' (3 cl) Portaskaig Conglomerate 142 



Islay. 



The Garvellachs, or Isles of the Sea. 



(3 e) Islay Quartzite 145 



North Islay. 

 Jura. 



East Islay. 



Scarba, Lunga, etc. 

 (3/) Port Ellen Phyllites 156 



East Islay. 



South-East Jura. 



(3 g) Laphroaig and Ardmore Quartzites 156 



(3 7i) Scarba Transition Group 157 



(3i) Easdale Slates 157 



(4) Pocks of Degnish and Shuna 157 



(4 a) Degnish Limestone. 

 (4 b) Ardrishaig Phyllites. 



III. Conclusion 158 



IV. Bibliography 159 



I. Introduction. 



As compared with the publications of the Geological Survey, 1 the 

 present paper includes the following new features : — 



(1) Direct structural evidence is offered of the superposition of the Lower 

 Torridonian sediments of the Rhinns of Islay upon the Lewisian Gneiss of 

 the southern part of that peninsida. Dr. Peach and Mr. Wilkinson were 

 not apparently on the outlook for big inversions, apart from such as are 

 introduced by thrusts, and so their interpretation of the structure required 

 confirmation. 



(2) The Loch Gruinart Fault is recognized, and its possible correlation with 

 the Great Glen Fault discussed. No dislocation is suspected in this position 



1 See Bibliography, §IV, p. 159. 



