Vol. 57.] COAL-MEASUEES OF THE SHROPSHIRE COALFIELDS. 



89 



I then tried similar cross-sections of the ground, ranging from 

 Ironbridge past Kemberton Pits in the direction of Shifnal, with a 

 similar result ; whence I concluded that the Madeley coal-basin 

 consisted of an unsymmetrical sj'-nclinal fold of Middle Coal- 

 Measures, having an east-north-easterly axis, the ridges or apices of 

 the bounding anticlines having been denuded of their original 

 covering of productive Middle Coal-Measures, and thus producing the 

 phenomenon known as the Symon 'Fault.' 



These observations not agreeing with the commonly received 

 opinion, first enunciated by Marcus Scott in the above-mentioned 

 paper, that the Symon ^ Fault ' consisted of a valley of erosion, 

 I carefully went over his paper with the object of elucidating 

 the cause of the inconsistency. I respectfully submit that the 

 following is an explanation of it i Scott took as his datum-line the 

 lowest workable seam of the older Measures, and the consequence 

 is, that when the Upper Measures are plotted out, they are made 

 in his section to occupy an unlikely position, as though they were 

 deposited upon a slope. Scott evidently forgot the premiss upon 

 which he had based his whole argument, for he said : — 



* It therefore occurred to me that it would not be an unwarrantable geological 

 liberty to assume that the coal-beds were originally deposited in an horizontal 

 position, or nearly so ' Quart. Journ. Greol. Soc. vol. xvdi (1861) p. 460. 



Had he kept to this rule, he would have been led to take as his 

 datum-line the basement-beds of the Upper Coal-Measures, and 

 his sections would then have given him a portion of another syncline 

 identical in form with, but larger in extent than, the Madeley 

 syncline. The following figure shows Marcus Scott's sections 



Fig. 3. — Section taken from Marcus Scott's paper, hut redrawn with 

 the basement-beds of the Upper Coal-Measures as a datum-line. 



N.N.W. 

 Pudley Hill Pit 



S.S.E. 



Cooks Wood Pit Stirchley 



"^ Grange Pit 



y777T77\ 



[Scales: vertical, 600 feet=l inch; horizontal, 40 chains=l inch.] 



plotted to the new datum-line, with the exception of Halesfield, 

 which is in the Madeley district. 



This syncline is both wider and deeper than the Madeley syncline, 



