LLANDRINDOD WELLS— CEFN LLYS, ETC. 



329 



Cefn Llys and to numerous knolls around and north of the church of Llandrindod, the best of 

 which is seen at Cet tws, about one mile south-east of Llan badar n- f a vvr . The rock is here a light 

 grey greenstone, containing much carbonate of lime, in strings and in larger veins, evidently of con- 

 temporaneous origin. This rock is also penetrated by dark ferruginous, pyritous veins. To describe 

 all these knolls would be useless repetition, the phenomena being invariably the same as those de- 

 tailed on the eastern side of the main ridge. At Llanfawr, north of the Pump House, the rock is 

 well exhibited, being largely cut into for the use of the roads. It is here a highly crystalline 

 greenstone, composed of hornblende and grey felspar more or less crystallized. The same rock 

 appears also near the Wells. In the hillocks around Llandrindod church are amygdaloids with 

 kernels of quartz sometimes coated with anthracite. These and other varieties protrude in almost 

 countless bosses, the schist or flagstone between them being highly indurated, dislocated, and 

 always much contorted. The mineral water of Llandrindod issues from black shale near one of 

 these points of contact. (See the end of the Chapter.) To the west of the springs the dull 

 features of Llandrindod Common, Llanyre Rhos, and the banks of the Ithon, are relieved by the 

 rapidly undulating outline, due to the mixed nature of the rocks, the soft shales being excavated 

 into deep and narrow ravines between these protuberances of trap. Among the latter there is no 

 one more picturesque than the rock on which stood the ancient fortress of Cefn Llys. Here the 

 river Ithon, in its course from the north-west, suddenly deflects and follows the edge of the main 

 ridge of the trap hills in a sinuous channel excavated in the Lower Silurian Rocks, winding round 

 Cefn Llys, which is thus almost peninsulated. Cefn Llys is composed of a coarse felspar rock, 

 having a tendency to porphyritic structure, and on one hand passes into a fine granular rock, on 

 the other to compact hornstone, sometimes very thin-bedded and slaty. On the summit are the 

 remains of buildings and foundations, &C. 1 ; but towards the northern end of the hill the trap as- 

 sumes the bedded character so frequently observable in other parts of this district. The well- 

 wooded and deep valley near the little church is singularly beautiful ; where the Ithon emerging 

 from this volcanized region through a narrow gorge of trap rocks, passes between cliffs of about 

 forty feet in height, from the sides of which a single plank serves as a bridge over the stream 9 . 



The covered nature of most of the depressions in this disturbed tract renders it exceedingly difficult, 

 if not impossible, to mark the nature of all the rocks beneath the surface. These valleys are for the 

 most part loaded with thick accumulations of the detritus of the adjoining ridges of trap and altered 

 deposits, the harder varieties of which form large angular boulders associated with much cold, light 

 yellow clay, the residue of the decomposed felspar. On the flanks of this district it is not, how- 

 ever, difficult to nwk with precision that the valleys really consist of a subsoil of black shale, schist 

 and sandstone, forming the Lower Silurian Rocks, i. e., from the base of the Wenlock formation to 

 below the Elandeilo flags, including the Caradoc sandstone. The manner in which some of these 

 deposits are affected by the intrusive ridges of trap has already been pointed out. 



1 Cefn Llys is one of the Radnorshire boroughs. 



2 This repeated alternation of trap and stratified deposits renders it impracticable to lay down every such 

 occurrence except upon a map of very large scale. 



