282 Meports and Proceedings — Geological Society of London. 



an east-north-easterly to west-south-westerly direction, but frequently 

 branch and run together, thus enclosing lenticular masses. 



Much of the faulting is of pre-Carboniferous age, but that it 

 continued into Carboniferous times is shown by the manner iu -^vhich 

 the Carboniferous rocks of the district have been affected. 



2. " The Geological Structure of Central Wales and the adjoining 

 region." By Professor Owen Thomas Jones, M.A., D.Sc, F.G.S. 



This paper deals with the structure on a large scale of an area of 

 about 1,800 square miles, comprising the western portion of Wales 

 between the K-iver Dovey and South Pembrokeshire. In an historical 

 introduction the work of earlier observers, notably Sedgwick, Ramsay, 

 and Walter Keeping, is referred to. 



The paper is accompanied by a map whereon is indicated the 

 distribution of certain rock-groups : this map is based partly on 

 personal observations and partly on information gathered from 

 various publications. 



On the map the structure of the area is easily perceived. There 

 are two principal anticlinal axes which follow in the main the valleys 

 of the Teifi and the Towy, and are named after these rivers ; between 

 them is an important syncline (the Central Wales Syncline) whicli 

 coincides nearly with the px'incipal watershed of Central Wales. 



Both the anticlines can be traced towards Pembrokeshire, where 

 they appear as important structures; but they cannot be distinguished 

 beyond the northern boundary of the area. The syncline, on the 

 other hand, becomes more important in a northerly direction, but is 

 lost towards the south-west. These structures have a southerly pitch 

 at the northern end of the district, and a pitch in the opposite 

 direction at the southern end. The variation in the pitch accounts 

 for the form of the outcrops. 



The peculiar correspondence between the evenly curved courses of 

 these structures and the form of the coastline of Cardigan Bay, as 

 also the relation of the structures to the other physical featai'es, are 

 discussed. 



May 1, 1912.— Dr. Aubrey Strahan, F.R.S., President, in the Chair. 



The President referred to the loss which the Society had just 

 sustained in the decease of Mr. Joseph Dickinson, at the age of 93. 

 Mr. Dickinson had been a Fellow of the Society for no less than 

 seventy years, having been elected in 1842, and he had retained 

 undiminished to the last his keen and vigorous interest in geological 

 and mining matters. 



The following communications were read : — 



1. " On the Geology of Mynydd Gader, Dolgelly ; with an Account 

 of the Petrology of the Area between Dolgelly and Cader Idris." 

 By Philip Lake, M.A., F.G.S., and Professor Sidney Hugh Reynolds, 

 M.A., F.G.S. 



Mynydd Gader lies immediately south of the area described by the 

 authors in a previous paper (Q.J.G.S., vol. lii, pp. 511-21, 1896). 

 The Tremadoc Beds are here succeeded by a group of rocks which are. 



