GEOLOGY OF PART OF SOUTH DURHAM. 



183 



Fig. 14. — Outcrop of Brockwell coal in Arnglll. 



To the south of Cockfield the outcrop of a thin coal may be 

 seen in a sandstone quarry near to Keverstone. The sandstone 

 is thick bedded, purple and yellowish, and irregularly stratified. 

 The coal beneath is rather over two feet thick, resting upon a 

 dark grey fireclay, and it dips with the sandstone to the north 

 and east. This coal is said to have been bored to further to the 

 west, near the Folly, in Raby Park. We look upon it as the 

 "Victoria" coal, lying from ten to twenty fathoms below the 

 Brockwell. 



We have not seen the outcrop of any coal so far south as 

 these just mentioned to the east of Keverstone, although some 

 beds occur on the road side near Hilton that apparently belong 

 to the lower part of the Coal Measures. A thin coal is also said 

 to have been seen in a well-sinking near Wackerfield. 



At Bolam the Cockfield Dyke cuts through a series of beds 

 which we take to be the Measures below the Brockwell. 



From the latter point the boundary of the Coal Measures ap- 

 pears to lie to the north of the Cockfield Dyke, trending in a 

 north and east line considerably north of Houghton-le-Side and 

 Heighington. 



There are old pits near Brussleton Folly which are said to 

 have worked a coal resembling the Brockwell ; and in a sand- 

 stone quarry a little to the north of the Royal Oak Inn, a two- 

 feet coal crops out to the south at a sharp angle. 



Further north-east, at East Thickley Quarry, some thick beds 

 of yellowish sandstone and shale belonging to the Coal Measures 

 are seen rising rapidly to the S.E., their edges abutting against 

 Magnesian Limestone lying unconformably over them. And at 



