Yol. 57.] COAL-MEASURES OF THE SHROPSHIRE COALFIELDS. 87 



the Upper (red) Measures, as at Hamstead Colliery ; secondly, as 

 pointed out by Sir Joseph Prestwich in his celebrated Memoir on 

 the Coalbrookdale field,^ it is never found in sinkings north and 

 east of the Severn, nor is it found in Eardington, Highley, 

 Billingsley, and other sinkings. I attribute this to the fact that, as 

 it is a thin bed, and has perhaps a tendency to thin out eastward, 

 its calcareous character has not been recognized by the sinkers. 

 It may be wiser, therefore, to take the following group of strata 

 as determining the base of the Upper Coal- Measure Series : — 

 Spirorbis-limestone where present, Main Sulphur Coal, Brick and 

 Tile Clays, Eough Rock, and Calamincar or Red Clay. Separating 

 this from the denuded beds of the Middle Coal-Measures a thin white 

 clay, 1 or 2 inches thick, is frequently met with. I am indebted to 

 Mr. Daniel Jones's kindness for all the sections (except Highley and 

 one of Billingsley) of the Forest- of -Wyre Coalfield that I have 

 particulars of. 



These Upper (red) Measures, whose basement-beds as just described 

 form wholly or in part an easily recognizable horizon, have a much 

 greater extension in the several coalfields of Shropshire than the 

 productive Middle (grey) Measures which in the Coalbrookdale Coal- 

 field and the Forest- of -Wyre Coalfield are found to underlie them. 

 In the coalfields near the town of Shrewsbury they are the only 

 series of Carboniferous rocks present, and rest immediately upon 

 Cambrian or other formations older than the Carboniferous, the 

 productive grey measures being entirely absent. 



In the Coalbrookdale Coalfield the respective areas of Upper and 

 Middle Measures are more nearly co-extensive, subject, however, to 

 certain lacunw in the Middle series which will be described more 

 particularly on a subsequent page. In the Forest-of-Wyre Coal- 

 field the Middle productive Coal-Measures are confined to the deeper 

 portion of the basin ; while the Upper (red) Measures extend 

 marginally beyond the subjacent series, so as to repose directly upon 

 Devonian or other ancient rocks, as in the Shrewsbury Coalfield. 



During a course of nearly twenty years' experience in the manage- 

 ment of collieries at Madeley (Coalbrookdale Coalfield), I was 

 impressed by the fact that whereas the seams of coal and ironstone 

 in course of being worked rose at an inclination of 10°, 20°, 30^, 

 and even 35° on the south-eastern flank of the Silurian limestone- 

 anticline, which is an underground extension of Wenlock and 

 Benthall Edges, the rocks on the surface immediately superjacent 

 to our working (which were Upper Coal-Measure strata) were 

 practically horizontal. I therefore plotted sections of our workings, 

 of which the appended diagram (fig. 1, p. 88) shows the result. 



Here then were some important facts : each workable seam, 

 whether coal or ironstone, when worked in a north-north-westerly 

 direction, or up the south-eastern flank of the anticline commonly 

 called the ' Limestone Fault,' was found to terminate a few yards 

 below the horizon where the shaft cut the Eough Rock with its 



1 Trans. Geol. See. ser. 2, vol. v (1840) p. 413. 



