132 J)E. G. L. ELLES ON THE BALA COUNTRY : [vol. Ixxviil, 



3. The Bala Coujsttey : its Stetjctfee and Rock-Succession. 



B3- G-EETEUDE Lilian Elles, M.B.E., D.Sc, F.a.S. (Read 



March 9th, 1921.) 



[Plate II — Geological Map.] 



Contents. 



Page 

 I. Introduction 132 



II. General Physical Features 135 



III. The General Succession 136 



IV. Details of Special Sections 144 



V. Structure of the District 157 



VI. Palaeontology 162 



VII. Comparison with other Areas 166 



VIII. Faunal Lists 169 



I. Inteoduction. 



The district dealt with in the present paper lies all round Bala 

 Lake, though attention has been paid more particularly to the 

 ground Ij^ing south-east and east o£ the lake, as affording an 

 opportunity for the study of problems of special interest regarding 

 the succession and structure of the area. 



The whole district has been classic ground since the days of 

 Sedgwick, and its difficulties were vividly described later by Jukes ; 

 it is just these difficulties that make the area so intensely 

 interesting, and, largely owing to the more detailed mapping that 

 can be carried out in these days, it is now possible to suggest a 

 solution of some, at any rate, of the problems — more particularl}^ 

 those of a stratigraphical and structural nature. The palseonto- 

 logical problems are somewhat different, and will not be dealt with 

 in detail at present. 



Previous Work. 



B}^ far the most important contributions made to our general 

 knowledge of the district are those of Sedgwick, Jukes, and 

 Ruddy, though Ramsay and, in later times. Lake have dealt with 

 the question of the faulting as connected with the development 

 of the valle}^ in which the lake lies. 



Sedgwick made two important contributions to the study of 

 the area. In the earlier paper on the * Calcareous Slates & Lime- 

 stones of (xljai Dj^ffws on the Holj^head Road, west of Corwen, & 

 of Rhiwlas north-east of Bala,'i he gave Avhat he believed to be 

 the succession in the area, and illustrated it by sections made as 



1 Proc. Geol. Soc. vol. iv (1843) p. 252. 



