384: TBANSACTIOMS OF SECTION C. 



Geological Features of the Visible Coalfields which bear ■upon the Distribution 

 and Structure of Concealed Coalfields in the South Midlands of Emjland. 

 In touching upon this question of possible buried coalfields in the Soutli 



Midlands of England, I wish briefly to refer to a few points connected with our 



detailed knowledge of already explored coalfields which must be taken into 



account. They may be grouped under two heads — 



(1) The stratigraphical breaks which are said to exist within the Coal 



Measures themselves ; and 



(2) The post-Carboniferous and pre-Permian folding, and its relation to 



pre-Coal-Measure movements. 



Geologists who have made a close study of the detailed sequence of any 

 British coalfield are fairly agreed that, while sedimentation was accompanietl 

 by a general subsidence, the downward movement was discontinuous, possibly 

 oscillatory, as evidenced, on the one hand, by the occurrence of marine bands 

 in a general estuarine series, and, on the other hand, by those coal seams, 

 particularly, which consist of terrestrial accumulations of plant-material. But 

 on a critical analysis of prevalent views we meet with considerable difference 

 of opinion as to the inferences to be drawn from the known facts. 



Jukes-Browne, referring to Conl Measure time, says ' that it was a period of 

 internal quiescence, a period in which terrestrial disturbances were at a mini- 

 mum,' ' and this notwithstanding his advocacy of the tremendous plication of 

 the Malvern and Abberley Hills in the middle of the Coal Measure period, 

 that is, in the interval between the Middle and Upper Coal Measures of England. 

 Another high authority says ' The Coal Measure Period as a whole was one of 

 crust movement.' ' 



Dr. Gibson, after a detailed survey of the North Staffordshire Coalfield, 

 where the Middle and Upper Coal Measures are fully and typically developed, 

 asserts that ' no break has been detected in the Coal Measiire sequence ' ; ^ and 

 a like conclusion is to be drawn from the work of the Government surveyors and 

 from borings in the Yorkshire, Derby, and Nottingham Coalfield and that of 

 East Warwickshire. 



Mr. Henry Kay '° would fix a local unconfonnity ,it the base of the Halesowen 

 Sandstone of South Staffordshire, and another at the base of the Keele Beds 

 (or so-called Lower Permian Marls) ; while in the Coalbrookdale Coalfield the 

 well-known Symon Fault, described by Marcus Scott as a great erosion-channel 

 in the Middle or Productive Measures, subsequently filled up by the unproduc- 

 tive Upper Coal Measures," Avas interpreted by W. J. Clarke in 1901 " as a 

 pronounced unconformity, a view which has been generally accepted ever since^ 

 and which was eagerly seized upon by those who' hold that the Malvernian 

 disturbance occurred at this time. 



The interrelation of the divisions of the Coal Measures is, in view of the 

 search for hidden coalfields, so important that I wish to pause for a moment to 

 consider the significance of the evidence for this unconformity which is said to 

 exist in the Midlands between the Middle and Upper Coal Measures. 



The plate which illustrates Marcus Scott's paper on the Symon Fault " shows 

 the upper beds plotted out from the lowest workable seam in the older measures, 

 which he assumes to be horizontal (their original position) ; while Clarke, using 

 Scott's data, plots his sections from the base of the Upper Measures, which he 

 uses as a horizontal datum-line.'' Incidentally I may remark that in both cases 

 the sections are drawn with a much-exaggerated vertical scale, and, of course, 

 correspondingly exaggerated dips. 



In my opinion, both these interpretations are )iiisleading (apart from the 

 question of scale), because in neither case is the adoption of the horizontal datuni- 



■ The Building of f/ir. British Isles, 1911. p. 1C9. 



^ Q.J.G.S., 1901, vol. Ivii., p. 94. 



" Q.J.G.S. 1901, vol. Ivii., p. 264. 

 '" Q.J.G.S. 1913, vol. Ixix., pp. 433-453. 

 " Q.J.G.S. 1861, vol. xvii., pp. 457-467. 

 " Q.J.G.S. 1901, vol. Ivii., pp. 86-95. 

 " Ibid. " Ibid. 



