366 Mr. Weaver's Geological Observations on 



and the western side of the vale that winds past Chew Magna, Chew Stoke, 

 and Sutton, toward the vale of Harptree. In that vale, a coal tract is found ; 

 while the low straggling hills on the east, which intervene between the vale 

 and the vicinity of Bath, appear to be composed of the new red sandstone 

 formation, supporting lias partially surmounted by oolite ; and on the west also, 

 in the Dundry range, a portion of the lower oolite is superadded, constituting 

 its upper part throughout. 



§ 46. The Broadfield Down range is a vaulted inflection of limestone, 

 nearly flat on the top, and inclined on the northern side, near Dundry, 25° to 

 the north-east, and on the southern, at the brow of Red Hill, 25° to the 

 south-west. This form is probably derived from that of the subjacent old red 

 sandstone, which, however, 1 have no where seen within this range : but the 

 limestone of Leigh Down range, which ascends to the north on the opposite 

 side of the vale of Ashton, reposes distinctly on the sandstone, as is well shown 

 in the course of the river Avon through those rocks. Broadfield Down is 

 furrowed on the western side by Brackley and Gobble combs ; and near the 

 mouth of the latter, the strata are gently undulated on the large scale in an 

 easterly and westerly direction. The limestone of both combs declines at an 

 angle of 15° to 20°, into the vale which contains the Nailsea coal-field. The 

 organic remains found in the carboniferous limestone of Broadfield Down are 

 analogous to those of Mendip. 



Local detached patches of the calcareous conglomerate occur also high up 

 on the limestone, as in the upper part of the defile that proceeds from Brackley 

 comb ; and here it partly supports shelly has limestone, similar to that of the 

 top of Aldwick hill. 



§ 47. The Bedminster coal-field on the south-western side of Bristol 

 (Section, No. 5), is overlaid by the second series of the sedimentary class, no 

 part of the coal formation coming out to the surface. But its immediate foun- 

 dation appears to be the same quartzy iron-shot sandstone as that of Brandon- 

 hill ; which reposes on the carboniferous limestone of Clifton and Leigh Down, 

 dipping 30° toward the east of south, and corresponding in this respect 

 with the broad belt of sandstone near Cromhall, of which it maybe considered 

 as the south-western continuation. In the Bedminster colliery are three seams 

 of good bituminous coal, two of which are wrought, namely the deepest and 

 the uppermost; the former being three feet four inches, and the latter two and a 

 half to three feet thick, while the middle seam has a thickness of one foot only. 

 The interval between the two principal seams is twenty-three fathoms. The 

 roof of the coal is shale, and the floor indurated clay. The dip of the coal beds 

 is, throughout this part of the vale, toward the east of south, at an angle of 20°. 

 This cofliery is at present worked by means of three shafts, of which the north- 



