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MESSRS. KIRKBY AND DUFF ON THE 



a new colliery lately sunk near New Shildon, on the south of 

 the Stockton and Darlington Railway, the Brockwell coal has 

 been reached at forty-six fathoms from the surface, rising quickly 

 to the south. 



We have no observation of our own from which to speak of 

 the southern limits of the coal-field still further eastward ; but 

 at Thrislington, Cornforth, and South Wingate, which may be 

 said to mark the extreme points at which coal has been wrought 

 to the south in that district, the coal seams are described as ter- 

 minating " by passing upward at a considerable angle into the 

 unconformable Magnesian Limestone beds."* So far as this 

 evidence goes it is in harmony with the idea of the coal-field 

 ending as a whole, as it is observed to end in part at its south- 

 western extremity. 



In the comparatively low country lying to the south of the 

 high ground above Raby, and south of Wackerfield, Hilton, and 

 Bolam, the prevailing Carboniferous rock is a coarse grained 

 sandstone or grit, of purple, grey, or yellow hue, with many 

 white quartz pebbles, and which is sometimes micaceous and 

 often false bedded, but which invariably dips a little to the west 

 or east of north. This rock may be seen at Langton, High Hal- 

 lam, Morton Tinmouth, Houghton Bank, Dun House, and near 

 Park House, and we have no hesitation in identifying it with 

 the Millstone Grit. 



To the south and west of the rock just noticed a series of 

 arenaceous strata, associated with a few calcareous beds full of 

 brachiopod shells and other marine fossils put in, which we take 

 to be the Yoredale rocks of Phillips.! 



* Wood, Taylor, and Marley, in Indus. Resour. of Tyne, Wear, and Tees, p. 6. 



t We were told more than once of coal having been wrought in former times near to 

 Winston ; and we met with one old collier who said that many years ago he helped to bore 

 to a four feet coal on the south bank of the Tees, opposite the church at Winston. The bor- 

 ing took place from the delivery drift of an old pit that had previously been sunk to the seam 

 and abandoned. The depth of the coal from the surface was twenty fathoms. 



We were also informed by Mr. George Graham that, near Gainford, he sunk seventeen 

 fathoms through grit to a coal two feet and a half thick ; a black band, one and a half feet 

 thick, was worked along with the coal. This Teesside coal does not appear to have been 

 very extensively wrought either at Winston or Gainford ; and the seam is probably one of 

 the two thin and inferior coals known to occur in the Yoredale series in the west of York- 

 shire and Durham. 



