Tol. 57.] THE UPPER COAL-MEASTJRES OP THE MIDLANDS. 261 



grey series overlain near the bridge at Pen-y-lan by red sandstones 

 and marls litbologically similar to the Keele Series. As in North 

 Staifordshire, these red measnres have been hitherto included in the 

 Permian. 



It will be seen (vertical section Ko. 2, ]). 252) that the Newcastle- 

 nnder-Lyme subdivision contains four thin seams of coal. In the 

 Ifton-Heath shafts (Davies, op. cit.), east of Grlyn Morlas, three 

 coals were intersected. The chief seam, consisting of 4 feet 

 9 inches of coal and 1 foot 11 inches of parting, is known as 

 the Morlas Main Coal, and is overlain by a strong rock, Coedyralit 

 Eock. The Morlas Main Coal is underlain by grey shales and 

 sandstones with two coal-seams. IN^o mention is made of a lime- 

 stone-band with entomostraca. In Glyn Morlas the limestone occurs 

 20 feet below a seam of coal underlain by grey sandstone. If 

 this corresponds to the lowest seam recorded in the Ifton-Heath 

 section, the total thickness of grey rocks above the red marls of Glyn 

 Morlas and Pentre-isaf Ravine would be between 330 and 350 feet. 

 The underlying red marls appear from Mr. Davies's account to be 

 about 840 feet thick. Eed marls, similar to those found in Glyn 

 Morlas and the Ceriog valley, are worked for bricks by the Euabon 

 Colliery Company, 1 mile north of Euabon. Good sections of the 

 red sandstones and marls, similar to those seen at Pen-y-lan, are 

 afforded by the large brick-pits at Pentre, south-east of Wrexham. 



The close lithological resemblance and the similarity of organic 

 contents of the strata just described with the Keele, Newcastle- 

 under-Lyme, and Etruria-Marl subdivisions of the higher Coal- 

 Measures in North Staffordshire renders it certain that the same 

 conditions marked the close of the Coal-Measure period in Denbigh- 

 shire as in the Pottery Coalfield. As equivalent terms for the 

 subdivisions in North Staffordshire, I would suggest Wrexham Eed 

 Sandstones and Marls, Coedyralit Series, and Euabon Marls. 



Whatever may be the relation in Denbighshire of the higher 

 measures to the productive series, it is of importance to note that 

 the upper series rests on some 800 feet of grey strata containing 

 numerous workable seams of coal. 



ly. South Staffordshiee. 



The succession above the Upper Sulphur Coal, 250 feet above the 

 well-known Thick Coal of South Staffordshire, was given by Beete 

 Jukes ' in ascending sequence as : — Eed Coal-Measure Clays 300 feet, 

 Halesowen Sandstone Series 400 feet, the latter being overlain by 

 the red sandstones and marls of Hunnington. The description of 

 these subdivisions given by Jukes recalls forcibly the Denbighshire 

 and North Staffordshire sequence. 



While mapping, under the direction of Prof. Lap worth, the 

 area of Carboniferous rocks south of Halesowen, I found a blue 

 limiestone with Spirorhis near the summit of the Halesowen Group. 



1 Mem. Geol. Surv. ' South StaflTordshire Coalfield' 2nd ed. (1859) pp. 28-31. 



