﻿55B 



DE. T. GEOOM AND ME. P. LAKE ON THE [jS^OV. I908, 



fragments, many of which are volcanic: among these are well-banded 

 rhyolites. The very coarse tuffs are naturally variable in thickness 

 and local in occurrence, but everywhere the band is distinct!)' 

 stratified. The accompanying section (fig. 2) shows the succession 



in the southernmost crag. 



Fig. 2. — Section of the southernmost crag 

 on the banJcS of the Morda, south of 

 Llechrhydau, on the scale of 1 inch to 

 5 feet. 



Fine ash. 



3= Fine ash. 



4= Coarse agglomerate. 



5= Fine ash. 



6 = Coarse agglomerate. 



7 = Mudstone. 



i=Fiue and medium-grained ash, extend- 

 ing below the foot of the crag for some 

 20 or 30 feet. 



The ash now leaves the line of the Morda, and enters the wood of 

 Cefn-coch. It is well shown in the stream that runs along the 

 north-western boundary of that wood ; but in the wood itself its 

 course is indicated merely by loose blocks, and farther east the only 

 actual exposure is in the little valley south of ' The Springs.' The 

 outcrop of the band, as indicated on our map (PI. LIII), is inferred 

 from the distribution of the ash-blocks and the contour of the 

 ground. 



]!vowhere in the course of this band have we seen any evidence of 

 intrusion ; and the regular stratification, the frequent alternations 



