After reaching the edge of 

 the scarp dominating the road 

 the ground rises gradually 

 eastwards from 1000 to about 

 1500 feet. The surface pre- 

 sents a succession of long 

 rocky ridges with intervening 

 hollows, which are usually 

 covered with peat. These 

 features are due to the folding 

 of the rocks, their direction 

 being that of the anticlinal 

 and synclinal axes. There 

 is no definite correspondence 

 between the position of 

 the axes and the ridges or 

 hollows, for in some cases an 

 anticlinal axis occupies the 

 crest and a synclinal axis the 

 hollow ; but more often these 

 relations are reversed, while 

 in other cases an axis runs 

 along one of the bounding 

 slopes. Also the hollows not 

 unfrequently coincide with a 

 belt of compression, where 

 two or three sharp folds 

 rapidly succeed one another. 

 All that can safely be said is 

 that the undulation of the 

 ground is an indication of 

 folding in the rocks, and that 

 the strike of the ridges and 

 hollows defines the direction 

 of the folding axes. 



The rocks are monotonous 

 in the extreme, in their 

 regular alternation of pale 

 greenish flags with thin gritty 

 bands. On this moorland 

 tract any soft shale-beds that 

 they may contain are masked 

 by superficial accumulations, 

 and consequently there is 

 little chance of obtaining 

 fossils. 



On the steep slope from 

 Banc Tymawr into the Myhe- 

 rin Valley exposures are more 

 continuous, and bands of 

 dark ironstained shale with 



