TRANSACTIONS OF SECTION C. 609 



successive unconformities to H h ) feet of Lowe* Lias. As this great hiatus occurs 

 in exact alignment with the northern edge of the coalfield, it is probable that it 

 marks a series of ' posthumous ' movements of the pre-Permian fold by which 

 the coalfield was defined. 



By a similar line of argument the southern boundary is connected with the 

 Charnwood axis, whose posthumous effects are seen in the dying out of certain 

 of the Mesozoic rocks, e.g., the Kimmeridge Clay near Cambridge. The eastern 

 margin is altogether more problematical. It may possibly be indicated by an 

 anticlinal fold near Willoughby and Louth in Lincolnshire, but no practical 

 importance attaches to the determination of the point, as the Coal Measures in 

 any case would be out of reach of the miner. 



Since the Report of the Commission was published borings have been put 

 down at Newark, near Thome, and near Selby that have proved the existence 

 of Coal Measures at those places, and have so far confirmed the conclusions in the 

 Report ; and I am now permitted to announce that a boring that is now being 

 put down at Scunthorpe, on the eastern bank of the Trent, has also proved Coal 

 Measures, and thus carries the proved coalfield another eleven miles to the east. 



(ii) The Coal Measures of the Concealed Yorkshire, Nottinghamshire, and 

 Derbyshire Coalfield. By Walcot Gibson, D.Sc. 



On the map accompanying Mr. Currer Brigg's Report on District D in the 

 Final Report of the Royal Commission on Coal Supplies for 1905, a triangular 

 area having its apex at the Haxey (S. Can) boring is marked off as the proved 

 extent of the concealed coalfield. The area thus defined amounts to about 

 460 square miles. To this, as the result of information obtained from several 

 borings for coal completed since 1005. there can be added about 200 square miles 

 situated north east of Haxey and about 200 square miles lying south-east of 

 Haxey. Much information has also been collected in the proved coalfield. The 

 new material, so far as it relates to the Coal Measures, may be considered under 

 (1) shape of the Palaeozoic floor, (2) character of the measures, (3) the workable 

 seams that are likely to occur within 4,000 feet depth, and (4) their probable 

 extension beyond the limits considered as proved in the Report of 1905. 



1. Palaeozoic Floor. — Between the outcrop of the Magnesian Limestone and the 

 River Trent, north of Nottingham, the Permian rests on a uniform plain with a 

 slope not exceeding two degrees and having a general direction to the east or 

 a little north of east. Over the faulted area, south of Nottingham, the uniformity 

 of slope has been broken; but outside the faulted belt the same even surface is 

 maintained between Ruddington, Edwalton, and Owthorpe. 



2. Character of the Measures. — The Barlow (Selby) boring in the north, the 

 Thome boring in the east, and that of Owthorpe in the south show that the Coal 

 Measures immediately beneath the new formations belong to an horizon several 

 hunched feet above the Top Hard or Barnsley Coal, which is a high and most 

 valuable seam in the coalfield. In these measures a marine band (20 to 50 feet 

 thhk) lies between 521) feet (Oxton boring) and 629 feet (Mansfield Colliery) above 

 the Top Hard Coal in Nottinghamshire, and, as ascertained by Mr. Ciilpin at 

 Brodsworth and Bent ley and by Mr. Dyson at Maltby, between 070 and 705 feet 

 above the Barnsley Coal in Yorkshire. The fauna, exclusively marine, is repre- 

 sented by fifty species distributed among thirty-seven genera. Many of the forms 

 occur in the shales below the Millstone Grits, and a few represent survivors from 

 the Carboniferous Limestone. The persistence, thickness, and fauna of the bed 

 indicate a general and a fairly prolonged incursion of the open sea during late 

 Middle Coal Measures. Minor incursions are represented by a few thin beds 

 occurring above and below this horizon in Nottinghamshire and Yorkshire. 



The thickness of the measures as a whole increases to the north and diminishes 

 to the east. 



3. The Workable Seams. — All the borings and sinkings strike Coal Measures 

 above the chief marine bed ; but, except at Oxton and Maltby, both situated in 

 the proved coalfield, the Upper Coal Measures have been completely removed by 

 pre-Permian denudation. The seams above the Top Hard Coal and Barnsley Coal 



