FRESHWATER LIMESTONE. 



83 



lowest of these, or the thin coal, being from about fifteen to eighteen inches thick. 

 The works at both these places are abandoned, those at Coedway having been wrought 

 during a period of twenty years. At Braggington a good deal of capital was recently 

 expended, but the thinness of the beds, their dislocations and high inclination, (close 

 to the edge of the trappean rocks of the Breidden Hills,) and their distance from any 

 good market, led to their abandonment. It appears, however, that the works were 

 conducted in an unscientific manner ; for there can be no doubt, that these beds of coal, 

 though thin, might, if well managed, prove of considerable use in this district in burn- 

 ing the contiguous limestone of the dolomitic conglomerate. (PI. 29. fig. 9.) The pre- 

 sent success of the pits at Westbury is indeed a proof of how much may be done by 

 spirit and assiduity. 



" Freshivater Limestone." 



The most remarkable feature in this coal-field, and one quite new to geologists when 

 I announced the discovery, is a .band of limestone, varying in thickness from three to 

 eight feet, which lies between the seams of coal. The following shaft section of the strata 

 at Pontesford shows its exact position, and explains the nature of the associated beds in 

 a part of the coal-field where they are perhaps most developed. 



ft. in. 



a. Gravel and detritus, thickness variable. 



b. Various overlying strata of variegated shale, sandstone, clods, &c, with traces of lime 



and ironstone. These are the beds of transition or passage from the Lower New 



Red Sandstone. (See better detail of these beds at Wellbatch, p. 91.) 90 0 



c. 1st or half-yard Coal, of good quality in some places near the outcrop, but generally 



more pyritous and sulphureous on the dip 1 6 



d. Poundstone and Crundall, i. e. variegated sandy shale, with traces of coal plants ... 60 



e. Sandstone, in beds of from three to four feet ; a good building-stone 27 0 



/. Reds, (stiff shale) , 6 0 



g. White Clumpitty (whitish shale) 12 0 



h. Lower Reds (mixed shale) 6 0 



i. Limestone, in two beds, the lower one adhering tenaciously to underlying sandstone . 7 0 



j. White Row I, yellowish white sandstone, with clods (clumpitty), &c 33 0 



k. Mush, a coal smut of varying thickness 3 0 



I. Black Clods, or finely laminated coal shale, with abundance of impressions of plants . 6 0 



m. 2nd, or Yard Coal, usually termed u Stinkers ", being highly pyritous and impure . . 3 0 



n. Clods, Sfc. as above, with a few thin laminae of coal and smut 54 0 



Oc 3rd, or Thin Coal, the hardest and purest coal in the shaft , 1 4 



255 10 



The limestone, as appears by this section, is here about seven feet thick, and is divided 

 into two beds, the uppermost of which is a compact cream-coloured rock, slightly 

 argillaceous, with a splintery conchoidal fracture and dull lustre. The lower, though 

 essentially the same limestone, is cellular, the cavities being filled with crystallized 

 carbonate of lime and black bitumen, both viscous and compact, and veins of calcareous 

 spar and sulphuret of iron are also disseminated through it. On the first examination 



