472 Notices of Memoirs—Concealed Coal-measures. 
boring is marked off as the proved extent of the concealed coal-field. 
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 1905, 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 coal-field. The new material, so far as it relates to the Coal- 
measures, may be considered under (1) shape of the Paleozoic floor, 
(2) character of the measures, (3) the workable seams that are likely 
to occur within 4000 feet depth, and (4) their probable extension 
beyond the limits considered as proved in the Report of 1905. 
1. Paleozoic Floor.—Between the outcrop of the Magnesian Lime- 
stone 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 Thorne boring in the east, and that of Owthorpe in the 
south show that the Coal-measures immediately beneath the newer 
formations belong to an horizon several hundred feet above the Top 
Hard or Barnsley Coal, which is a high and most valuable seam in the 
coal-field. In these measures a marine band (20 to 50 feet thick) lies 
between 520 feet (Oxton boring) and 629 feet (Mansfield Colliery) 
above the Top Hard Coal in Nottinghamshire, and, as ascertained by 
Mr. Culpin at Brodsworth and Bentley and by Mr. Dyson at Maltby, 
between 670 and,705 feet above the Barnsley Coal in Yorkshire. 
The fauna, exclusively marine, is represented 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 coal-field, the Upper Coal-measures 
have been completely removed by pre-Permian denudation. The 
seams above the Top Hard Coal and Barnsley Coal are irregular in 
their occurrence and of uncertain quality. In the Doncaster and 
Thorne area the Dunsil Coal 50 feet below the Barnsley bed appears 
to be a valuable seam, but it deteriorates south of Doncaster. Most 
of the lower coals over the recently proved extension of the coal-field 
lie beyond the limit of profitable working. The future resources of 
the coal-field therefore mainly depend upon the thickness, quality, and 
depth of the Top Hard or Barnsley Coal. 
4. Hxtension.—As a result of the explorations made since the Report 
of 1905 the proved limit of the concealed coal-field may with some 
