Part of Gloucestershire and Somersetshire. 345 



1. At topj — strata of sandstone conglomerate. 



2. A bed of limestone^ 2 to 3 feet in thickness. 



3. Fine-grained reddish sandstone. 



4. Thin beds of quartzy sandstone^ with slight layers of slaty sandstone. 

 The limestone No. 2. contains numerous entrochites^ and also some turbi- 



nites. The subjacent red sandstone No. 3. is^, in the line of contact^ firmly 

 adherent to and incorporated with the limestone^ and contains casts of tere- 

 bratulites and entrochites, composed of calcareous spar ; but at a greater 

 depthj the carbonate of lime disappears^ and there is left a porous^ easily fran- 

 gible sandstone^, bearing the impressions of those remains. The quartzy 

 sandstone beneath. No. 4, exhibits casts and straight and curvilinear protu- 

 berances, apparently referable to coralloid or vegetable remains ; and also 

 casts and impressions of Cacti, analogous to those described by Martin in the 

 Petrijicata Derhiensia. The Rev. Mr. Woollcombe, in excavating for his 

 cellar at the Rectory, found in the sandstone impressions of caryophyllites, of 

 productilites, and other bivalves. 



From this spot, the sandstone extends uninterruptedly to a dell or hollow, 

 that borders on the coal-field, and which seems, in a manner, to form its 

 natural boundary. On the south side of the dell, the sandstone, which thus 

 immediately underlies the coal-field, dips in the northern quarter 16" toward 

 the west of south, and in the western quarter 20" to the south, 20" east, being 

 gently undulated both in the line of range and dip. It is composed of white 

 or gray fine-granular quartz, with a few minute scales of silvery mica, and 

 contains in some places compact brown ironstone, and hsematite, in slight 

 [(interrupted layers, or in disseminated portions ; and it is traversed by slight 

 fissures, the surfaces of which are coated with oxide of iron of a deep red 

 colour. Impressions and casts of stems and branches of plants are not un- 

 frequent in this sandstone. 



§ 24. The coal formation near Cromhall, forms the northern extremity of 

 an extensive coal tract, which passing to the south toward the Bristol Avon 

 diverges thence into the vales of Somersetshire. Of the coal tracts of Glouces- 

 tershire and Somersetshire, we are promised a detailed account from the 

 joint researches of Professor Buckland and the Rev. W. D. Conybeare; and 

 the subject being in such able hands, I shall confine myself to such notices as 

 are immediately connected with the lines of section which I have given, of 

 certain portions of those tracts. 



The Cromhall coal-field has been partially explored on its northern and 

 north-western edge, by means of pits and shallow levels connected with the 

 dell mentioned in the last section. But the principal work was established about 



2y 2 



