Mr. De la Beche on the Geology of Southern Pembrokeshire. 19 



Miner's Names. 

 Rock 



Section at Begelly Collieries, from the Surface downwards. 



Thickness. 

 Ft. In. 

 variable according to the 

 situation of the pit. 



Upper or Rock Vein 



Dunstone 



Binder 



Rock 



Slate 



Siliceous grit 



{ 



} • 



from 1ft. 



6in. to 



} 



3 



6 



9 







9 







3 



6 



6 







1 



10 



7 







2 







3 







4 







15 



Stone-coal 

 Shale 

 Shale 



Siliceous grit 



Slaty shale, with abundance 

 of ironstone nodules 

 Low Fein .... Stone-coal 

 Dunstone .... Shale 



Slate ..... Slaty shale 

 Rock ..... Siliceous grit 



Binder Shale 



Slate ..... Slaty shale, with abundance 



of ironstone nodules 

 Timber Vein, so called from the ^ Stone-coal, with abundance "\ 



quantity of timber required to p> of mineral charcoal at the > from 5ft. Oin, to 6 

 support the roof . . J bottom ... J 



Dunstone .... Shale .... 30 



Rock ..... Siliceous grit . . . unknown. 



Upon a flat between the villages of Begelly and Jefferston there are some 

 singular basin-shaped masses of stone-coal. The easternmost was discovered 

 in 1818. It resembles in shape a semi-oval, the section passing through the 

 longer axis. Its length from east to west is about one hundred and forty 

 yards ; its breadth from north to south, forty yards ; its depth, ten yards. This 

 mass of stone-coal is covered to the depth of two feet by yellow clay, contain- 

 ing rounded pieces of compact siliceous grit : it rests also upon clay. 



At the distance of twenty yards to the west-north-west of the above, a simi- 

 lar basin of stone-coal is now worked, which is probably of nearly the same 

 dimensions with the former; but its limits are not yet exactly ascertained. 

 Three similar basins, though very small, are found to the west and north of 

 the second. All these are covered by clay containing rounded pieces of grit. 

 It is difficult to account for these basins, since in their immediate neighbour- 

 hood the strata dip gently to the south-west. 



At several places on the southern and northern limits of the basin the lowest of 

 the coal-measures are very thick, and consist of a very compact quartzose sand- 

 stone, equivalent probably to the millstone grit of other coal-fields. A bed of 

 this rock occurs above the limestone at Gouldtrop Road ; large blocks of it are 



D 2 



