.532 



JPROF. W. J. PUGH ON THE GEOLOGY OF THE [vol. lxxix, 



until along the outcrop of the Narrow Vein it may he as much as 

 70° : as, for instance, at Aherllefenni. This steep clip is normally 

 maintained or even increased, until the outcrop of the Derwen Beds 

 is reached : for example, the Cwmere Beds at Brynlhvyd Quarry, 

 south of Corris, dip south-eastwards at 88°. The dip then gradually 

 decreases as we come upon the outcrops of the Ystwyth Stage. 



Just as the Harlech Dome itself is crossed by folds minor in 

 comparison with that great anticlinal structure itself, so in the 



Fig. 4. — Diagrammatic sketch of the Corris Anticline, as seen in 

 the southernmost quarry at Braich-goch, Corris. 



approximately 25 yards 



l=Narrow slate-vein. 2 = Garnedd-wen Beds (mudstones 

 with thin grit-bands). 



Corris area there are folds which trend transversely to the normal 

 strike of the beds, and cause considerable deviations in the general 

 direction of the outcrops. 



The area is crossed by two important anticlinal structures, one 

 in the west which Ave may call the Corris Anticline, and the 

 other farther east which we may call the Aherllefenni 

 Anticline. The axes of these two folds trend north-north-east 

 and south-south-west, and in some places approximate]}^ north and 

 south. 



