606 ME. D. C. EVANS ON THE ORD0VICIAN [Nov. I906,, 



neighbourhood, however, where some members of the series are 

 found, fossils are very common. These beds, which here consist of 

 bands of grit alternating with shales, are well seen striking across 

 the road immediately north of the farm, and trilobite-fragments 

 and Orthis are fairly abundant both in grits and shales. Heads 

 and tails of Ogygia marginata are met with, and OriJiis Carausii 

 (Salt.) is common. 



There are apparently three isolated patches of these grits in the 

 neighbourhood of Pound-glas and Llwyngwydd, in which several 

 small quarries have been opened. Their presence is indicated by 

 the abundant loose debris and the character of the soil. The small 

 quarry in tbe wood north-east of Llwyngwydd shows these grits 

 dipping under higher beds. 



Another isolated patch of these grits caps the hill south of Pass- 

 by, and a quarry has been opened in them at Pencilpost. The 

 coarsest bed here has yielded an Orthis ; a few trilobite-fragments 

 and bits of dendroid graptolites have also been found here. Some 

 of the beds crop out with a southerly dip, ar, the bend in the old 

 lane north of Pencilpost, and here they are fairly crowded with fossils, 

 including a large Lingula, Ogygia cf. marginata, Crosf. & Skeat, 

 Trinucleus cf. SedgwicJcii, Salt., Orthis Carausii, Salt., 0. Menapice, 

 Hicks, etc. 



The hollow between this section and Pass-by Cottages is in shale;, 

 but immediately north of the Cottages the grits are again seen 

 striking across the road with a northerly dip, and containing fossils 

 of the usual type. The abundant debris along the crest of the hill 

 to the north, extending from Cwmfelin-boeth to JS'ant-clomendy 

 Dingle, indicate their presence and strike, and small quarries have 

 been opened in these grits in several places. They are seen passing 

 under higher beds at Cwmfelin, where they have been considerably 

 disturbed. A fault of some magnitude is seen in a quarry on the 

 west of the valley, and its effects are shown behind a cottage on the 

 east side also. This fault probably accounts for the non-appearance 

 of the grits in the JNant-clomendy dingle. 



Farther north are two outcrops of the same series of beds. One 

 extends from a point a little north of Aberdauddwr, where it is 

 exposed in a small quarry in gorse-grown ground, to another point 

 a little west of Pantyffynnon. They are seen crossing the stream 

 by the Old Cottage in the dingle — east of Blaenweneirch, and passing- 

 westward they form the feature south of that place. They also form 

 the hog-backed ridge west of Pantyffynnon. Some of them are seen 

 in the yard at that place, where they and their associated beds show 

 signs of considerable disturbance. North of Aberdauddwr they 

 have yielded Orthis Carausii, Salt., and Dendrograjptus-fiagments. 

 South of Blaenweneirch similar fossils occur. 



The other and northernmost outcrop, a little farther north, is 

 more extensively developed, and is slightly different in character. 

 The beds are exposed in the dingle east of Blaencediw — 200 yards 

 or so below the springs. Many small quarries have been opened 

 in them in the immediate neighbourhood — one at the bend in the 



