158 



DE. G. L. ELLES OX THE BALA COr^'TET : [vol. Ixxviii, 



puUisliecl regarding 

 disturbance has been 

 normal fault with a 



the nature of the Bala Fault ; this line of 

 held by Jukes, Eamsav, and others to be a 

 maximum downthrow to the north-west of 

 about 11,000 feet. The nature of 

 this displacement appears to be dis- 

 tinctly more complex when viewed in 

 the light of completer knowledge, 

 and instead of being continuous with 

 the Dee-Yalley Fault in the manner 

 shown on the 1-inch Greological Sur- 

 vey Map and accepted by Sir Aubrey 

 Strahan,! it runs up into the country 

 north of the lake ; there it appears 

 to have been profoundly affected by 

 later post- Carboniferous movements. 

 The evidence in the district as a 

 whole clearly points, however, to its 

 having been initiated as an im- 

 portant structural line in connexion 

 with the Caledonian System of 

 foldino:. 



The Bala district forms part of 

 the southern limit of the great S- 

 shaped buckle of rocks round the Har- 

 lech Dome, so beautifully brought 

 out by the outcrop of the volcanic 

 rocks ~ ; the trend-lines are in the 

 main those of the Caledonian System 

 of folds modified by local circum- 

 stances, the modification in this case 

 being primarily due to the presence 

 of the Harlech Dome. 



The whole country may be re- 

 garded as folded round and against 

 the Harlech Dome by pressure acting 

 from a general south-easterly direc- 

 tion : thus, in the area here de- 

 scribed, the primary folding appears 

 to follow north-east and south-west 

 trend -lines in those parts of tlie 

 district north and south where the 

 rocks escape more or less from the 

 influence of the Harlech Dome ; but 

 in the intervening area where that 

 influence is fully felt, the axes of 

 the folds run approximately north and 

 south. Neveitheless, it is the north- 



1 Pres. Address to Sect. C, Eep. Brit. Assoc. (Cambridge) 1904, p. 535. 

 - Geological Survey of England & Wales :^-inclL maps : New Edition, 

 Sheets 9 & 10. 



