﻿Vol, 64.] BALA AND LLANDOVERY ROCKS OF GLYN CEIRIOG. 



565 



sharp boundary-line can be drawn. A peculiar feature here, which 

 is also visible to some extent in Cae-Deicws Quarry, is that the 

 felstone is sometimes banded. Kear the fault the banding is ap- 

 proximately parallel to the plane of the disturbance ; but in some 

 cases the banding is nearly parallel to the jointing of the rock, and 



Pig. 9. — Section at the top of the Craig-y-Pandy Ash, in the China-clay 

 Quarry. (Scale : 1 inch = 4 f^^t-) 



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Blue shales 



and 



thin limestones 



with 



fossils. 



(Base of the 



Bryn Beds.) 



Fossiliferous false - bedded 

 tuif, with occasional large 

 fragments, together with 

 seams of slate (shown 

 in black). (Top of the 

 Craig-y-Pandy Ash.) 



Unfossiliferous tuff 

 with fragoients. 



occasional blocks show an appearance very similar to that of the 

 Moughton Whetstones. The bands differ one from the other in 

 no respect but colour, and are evidently of secondary origin. At 

 Craig-y-Pandy there is also a rudimentary attempt at the columnar 

 jointing which is so well displayed at Cae Deicws. 



The felstone has been extensively quarried, both at Pandy Quarry 

 and at Cae Deicws, for the manufacture of china-clay and for setts. 



(4) Bryn Beds. — Leaving out of consideration for the present 

 the intrusive sheet worked in Coed-y-glyn Quarry, and seen at 

 intervals throughout the district, the beds above the Craig-y-Pandy 

 Ash and below the fault consist mainly of sandstones and shales, 

 both of which are sometimes calcareous. Immediately above the 

 ash at the China-clay Quarry itself, they are especially charac- 

 terized by a great abundance of Bajinesquina itngula, while the 

 beds somewhat higher in the series are distinguished by the number 



