96 



THE GEOLOGIST. 



upper-measure seam east of the Taff. The Mynyddswlyn- vein, three 

 feet thick, is the great vein from which the red ash, or home-burning 

 coal is sent to Newport and Cardiff. It occupies a rather narrow 

 tract of country, runing east and west from Pontypool to the Taff. 

 The railway which goes across Cwmhn Bridge takes us through the 

 very centre of this tract, which is very thickly studded with colleries, 

 and cut up with a number of small faults A good idea of it will be 

 gained from the horizontal section of the Government Survey, I^o. 

 12, as it runs through the Cefn Crib mountain to crop out at Cred 

 Colynos, above Pontypool. It usually consists of a top- and bottom- 

 coal, divided by a varying amount of rubbish, or parting — for instance, 

 at the south-east crop of this vein, which is to be found at the 

 Penner coUiery, near Newbridge, the division is thirty-three feet 

 thick ; but on the north crop, at Tophill, near Llancaiach, overlook- 

 ing the Taff Yale, it is only a foot and a-half ; so that the two veins 

 can be conveniently worked together. I append a section of this 

 coal as worked at the Mamhole-coUiery, in the Sirhowy YaUey, the 

 property of Sir. Thos. Phillips ; — 





Ft. 



in. 



Surface 



19 



6 



Rock 



33 



0 



Clod 



8 



0 



Thin coal (The Rider) 



1 



2 



Clod 



30 



0 



Rock 



64 



0 



Clod 



30 



0 



Coal (top) 



3 





Clod 



1 



i! 



Coal (bottom) 



2 





The clod soon begins to thicken, even in the space of a few 

 hundred yards, as does the coal itself. 



From the measures at Pontypool several coal-plants have been ob- 

 tained ; but the most interesting fossil there is found in the iron- 

 stone, just above the Meadow-vein. It is the Procludus scahriculus, 

 the only Productus ever found in the true coal-measures, and as far 

 as I have been able to ascertain, the only specimens as yet found 

 in the district. Here they are very plentiful. 



As wc follow up the Afon and Frwd valleys we successively arrive 



