Vol. 62.] ORDOVICIAX OF WESTERN CAERMARTUEXSHIRE. 623 



About 100 yards south of Cefn-pant Chapel there is another 

 short outcrop let out by an east-and-west fault, seen in section in 

 Canerw Quarry. (The Didymograptus-JIurchisoni Beds are not 

 seen at the quarry.) This outcrop strikes into D.-bifidus Mudstone 

 at Trehir-isaf, and no more of it is seen farther west. 



There is yet another extensive, but much broken outcrop, let out 

 by the complicated faulting of Xant-yr-eglwys. The easternmost 

 exposure in this outcrop is seen in a field, at the end of the lane 

 south of Aiaencoch. The beds are also exposed in the lane itself, and 

 there is much debris in the soil for some distance south, but not in 

 line with the strike of the beds in the lane ; besides, the lane-beds 

 strike into Dicranograptus-Beds in the immediate neighbourhood. 

 [North-westward these beds are traceable to a point some little 

 distance south of Llain (Lleinau), where the lower division is seen 

 in a road-exposure, and the whole in the bed of the river to the 

 west. A small quarry has been opened in them south of Tre- 

 bleiddiau, and they are seen crossing the road close by. There is 

 no other exposure, but debris is traceable a Quarter of a mile farther 

 along the same strike, which euds abruptly in D.-bifidus Beds, the 

 D.-Murchisoni Beds being thrown about 200 yards to the north, 

 and cropping out in the lower part of Wern-berni farmyard. From 

 here they strike due westwards, and are seen again at Cwrtau-bach, 

 in the lane near the well; but here the beds are much cleaved, and 

 are disturbed by a fault which causes a slight displacement. A 

 quarter of a mile to the west they are faulted down, and pass under 

 higher beds. 



The ground round Llwynllwyd is very complicated, owing to 

 much faulting. Although lower and higher beds are abundantly 

 exposed, there is no well-defined outcrop of D.-Murchisoni Beds. 

 Slight traces of them have been detected in several localities, but 

 there is not a single exposure. A little farther north, however, 

 the whole series is again seen in the dingle north of Tycoed, and is 

 traceable westward to Abertigan, being faulted on the south against 

 DicranograpytasShales. The beds are well seen in the watercourses 

 south of Abertigan and on the road at Tigan, immediately north of 

 the ford near Llanglydwen Station. 



On the west of the river there is a complete section across them 

 near the bridge, where the three divisions are well represented. 

 The ash has been quarried here, just where the limestone-mark is 

 on the Survey-map. There are calcareous lumps in the ash, and 

 some attempts have been made to burn them. The kiln built for 

 that purpose was standing until very recently. It cannot be made 

 out, however, on what grounds it was thought that there are lime- 

 stone-rocks here in contact with a cupriferous vein. There are some 

 old workings a little distance to the south, but there are no limestone- 

 rocks, neither was any copper found. 



The Didymograptus-Murchkoni Beds run westward through the 

 * Castell ' and come out on the road near the mill, and at the junction 

 of the roads south of Pengawsai, where the ash is extensively quarried 

 for road-metal, and the striped beds are exposed in the roadway. 



