D. Jones — Denudation of Coalbrooh-dale. 205 



tte Chance Pennystone. Mr. Prestwich seemed to think that the 

 reason why the Chance Pennystone was not known in the southern 

 part of the Coal-field was that the nature of the stratum had changed 

 in its extension southward. But this is not so, as both it and the 

 Fungous Coal are entirely absent. Mr. Eandall, who recently con- 

 tributed a series of letters to the Mining Journal on the Shropshire 

 Coal-field, speaking of the Chance Pennystone [vide Letter No. 7), 

 says, " This ironstone, as the name implies, has always been found 

 to be irregular and uncertain ; it was confined to the south of the 

 Coal-field, like the others already described in this article, and is now, 

 we believe, entirely exhausted." The word "south" should have 

 been " north," as Mr. Eandall has explained to me. 



From 60 to 80 feet below the Gur Coal, we have the Top Coal, a 

 seam having a much wider range to the south than any of those 

 previously mentioned. We have it in the Granville Pit, which I 

 may remark by the way is the only pit shaft in which a regular 

 sequence from the lower Coal-measures into the upper is traceable, 

 and is consequently the most typical of the original Coal-field ; all 

 the other shafts give evidence of subsequent change by denudation. 

 The Top Coal is wanting in the Stafford Pit. As the Three Quarter 

 Coal, lying a few feet below, is found in that shaft, the denuded edge 

 of the Top Coal cannot be far to the west of the shaft. It then falls 

 back to within a short distance east of the Puddley Hill Pit and 

 Langley, then passing to the east as far as the new pit at Kemberton, 

 it is there found to exhibit signs of denudation. Following an 

 irregular line, somewhere between Madeley Court and the Meadow 

 Pit at Madeley, it runs northward towards Great Dawley and east of 

 Lawley, and is lost a little south of Ketley, against the western 

 boundary fault. It does not occur in the Madeley Meadow Pit, and 

 is not met with in any portion of the field to the south of that shaft. 

 It will not be necessary to trace the boundary of the Three Quarter, 

 Double, and Yard Coals ; it is sufficient to say that they are cut off 

 in succession by the same process of denudation one after another. 



We will now trace out the denudation of another zone shown 

 on the map (Plate V.), which will include approximately the Big 

 Flint Coal, Pennystone, and Sulphur Coal. These strata are found 

 as far south as Broseley. Their boundary passes a little north of 

 Amies ; it then passes eastward for some distance near Kemberton, 

 and eventually northward in a line of the same character as that in 

 the Top Coal, more or less parallel to it. The Clod Eandle and 

 Little Flint Coals behave in the same manner to the south, and 

 eventually the base of the Coal-measures, Silurian Limestone, is 

 met with, and there is an end of the productive Coal-measures. 

 Coal-measures are met with still further south for many miles, but 

 they are all upper Coal-measures, except at Harcott, where a patch 

 of the older Coal-measures, like that at Shirlot, is met with beneath 

 the younger formation. I believe I am the first to point this out ; 

 and I may go further by saying that I have established, to my own 

 satisfaction at least, the co-relation between the patch at Harcott and 

 those on the two Clee Hills ; but this is not the place to enter into 



