252 Rev. James Yates on the Structure of the 



Since Mr. Keir published his description of the South Staffordshire Coal- 

 field, including a particular account of his own colliery at Tividale, he sunk 

 there a shaft (named Pit N" 11), 55 yards in depth, after which he came 

 to a solid rock of greenstone similar to that of the adjoining hills. The 

 shaft was continued through it to the depth of Sb yards. The workmen then 

 came to coal 4 yards thick, which they described to be in the state of cinders. 

 This pit is at a considerable distance from the base of the Rowley Hills, and 

 on the further side of the road to Oldbury, between it and the Birmingham 

 canal. The other pits in the same colliery are situated towards the south, 

 between N" 1 1 and the Rowley Hills, and also towards the west and north, 

 but in none of them was greenstone found. If, therefore, this mass of green- 

 stone communicates with the Rowley Hills, it is probably in a direction 

 towards the S. E. Greenstone has been found in the same manner more than 

 two miles from the Rowley Hills at " Moat Colliery," and at Mr. Finch's col- 

 liery near West Bromwich. 



Since the publication of Mr. Keir's account, coal has been got further east- 

 ward, and the result is of some importance in the geology of this district. 

 Shafts have been sunk in the Square Field Colliery near the Swan at West 



arch. The hill is about half a mile long. The three strata of limestone, (marked '2, 3, 4.) which 

 lie towards the west, meet at the southern extremity of the hill, inclosing it with a very uniform 

 curvature; while the stratum (marked 1,) which lies nearest to the eastern verge of the hill, 

 bears towards the Castle Hill on the south. All these strata make a smaller angle with the 

 horizon in proportion as they approach the same part, and seem at length to dip under the adjoin- 

 ing transverse valley. At the northern extremity of the hill, they are diverted from their course, 

 their continuity being broken. All of them incline from this point towards the N.W. and form 

 a ridge, which, though a continuation of the Wren's Nest, is of inferior elevation, and is called 

 Mon's Hill. The beds of limestone, which mantle round the interior of bavin, rise on each 

 side above the general level of the hill, so that their projecting edges inclose a valley on its sum- 

 mit. The dotted portions of these strata show in the section the parts, which have been removed 

 in the process of mining by open work. The greatest mass has been taken from the western side 

 of the hill, where the removal of the dotted part C D has exposed to the day the highly inclined 

 face of a bed of bavin, full of shells, corallines, entrochi, and trilobites. The inner strata of 

 limestone (marked 2, 3,) are each 11 yards in thickness; the outer, (marked 1,4,) 8 yards. 

 The thickness of the bavin between the strata (1 and 2) on the eastern side of the hill, nearly cor. 

 responds with its thickness between those on the western side. The section of the Castle Hill 

 discovers four strata of limestone, approaching to a vertical position, converging towards the 

 middle of the hill, and almost exactly corresponding in thickness, and in their relation to the in- 

 terposed bavin, with the strata of the Wren's Nest. All these circumstances conspire to prove, 

 that the strata have been elevated from a position nearly horizontal ; and there seems sufficient 

 ground for the inference, that the mass of greenstone, which forms the remainder of the chain of 

 hills towards the south, is continued northwards under the elevated strata of limestone. 



