South-western Coal District of England . 257 



heathj forming a broad band through the parishes of Iron Acton^Winterbourn, 

 Stoke, Mangotsfield and Westerleigh *. On the south-east of Winterbourn 

 it rises into some broken hills, conspicuous in a country for the most part tame 

 and flat ; and along the course of the river Frome below Winterbourn, as far 

 as Frenchhay and Fishponds, it constitutes a defile, which occasionally as- 

 sumes a picturesque character. Along the southern edge of this zone, where 

 the Pennant rests on the basset of that coal-seam in the lower shale, called the 

 Cock-vein, it dips very rapidly to the north and north-west. This may be par- 

 ticularly observed in the defile of the Frome to the south-west of Fishponds ; 

 but on the opposite side of the river near Frenchhay, it rises at a very low 

 angle in an opposite direction ; that is, towards the limestone, which between 

 Henbury and Almondsbury forms the boundary of the coal-field ; though here 

 the interval between the Pennant and the limestone is concealed by red marl 

 and lias. It appears from the dip of the strata at Stoke and Mangotsfield, that 

 on approaching the ridge of K'ngswood they are bent round it in the manner 

 represented in the annexed figure. 



A, Stoh 



^inc/dfxfood 



In all other parts of the zone, the Pennant dips towards the centre of the 

 northern trough in Coal-pit heath, and usually at a considerable angle. To 

 the north and south of this zone, the lower coal-shale, as has been already 

 stated, may be traced beneath the Pennant ; but it is concealed to the east and 

 west by the red marl and lias, which overlie the exterior edge of the Pennant; 

 the shale however seems to have been proved at Pucklechurch beneath these 

 horizontal deposits. 



The zone of Pennant that encircles the upper coal-shale in the trough to 

 the south of Kingswood, is only very partially exposed. It is defined most 

 clearly along the banks of the Avon between Keynsham and Bristol, where it 

 forms a tract about three miles broad, traversed by a defile of that river and by 

 the precipitous valleys of some tributary streams. This elevated tract is sepa- 

 rated from the platforms of red marl and lias to the south of it by a broad val- 

 ley, raised about 50 feet above the level of the Avon at Keynsham, through which 

 the intended continuation of the Kennet and Avon canal was to have passed. 

 This valley appears at a little distance to be the only outlet through which the 



* At Oatley, to the S. W. of Westerleigh, a quarry of the Pennant is wrought for stone-tile. 



2l2 



