488 



WENLOCK LIMESTONE OF WALLSALL. 



Wallsall. 



The Wenlock formation is spread over a much wider space around the town of 

 Wallsall than in any other part of Staffordshire, occupying a width of about two and a 

 half miles, from the Hay Head lime works on the east, where it is overlaid by the de- 

 tritus of the New Red Sandstone, to the great limestone fault on the edge of the coal- 

 field. Its greatest length is about four miles, from near Bustleholm Mill on the south- 

 west, to beyond Daw End on the north-east. The strike of this mass is north-east and 

 south-west, thus differing essentially from the axes of the ridges near Dudley. Judging 

 from the form of the ground where limestone has been proved, as beneath the town of 

 Wallsall and at Ball's Hill, the rock has been partly thrown up in domes, though the chief 

 masses occupy sharp parallel ridges, trending from north-east to south-west 1 , the beds 

 dipping rapidly to the north-west at angles of 40° to 50°. The most prominent of these 

 bands are between the town and the edge of the coal-field. 



The limestone worked at RushalL, Daw End and Wallsall is about 11 yards thick, and having 

 been long exhausted at the outcrop, is extracted by shafts, at depths varying from 60 to 100 yards. 

 The clearest relations of this rock to the overlying coal measures are exposed in the sides of the 

 abandoned reservoir between Rushall Hall and Daw End, where ironstone beds and thin layers of 

 poor coal measures, repose at a slight angle of inclination upon the impure limestone and shale 

 (" bavin and rotch ") of the formation. Similar relations have been proved along the eastern edge 

 of the coal-field near the Birch Hill collieries, where the limestone has been actually reached be- 

 neath some of the ironstone measures. By far the greater portion of the Silurian rocks around 

 Wallsall, particularly in the cold argillaceous tract extending by Delves Green and Botany Bay to 

 the new Railroad, consists of the lower shale 2 . 



The eastern boundary of this Silurian tract contains a narrow band of limestone, traceable for 

 upwards of a mile, from Ginity Graves to the Hay Head, where it has been long worked in open 

 quarries, which are still productive, owing to the strata dipping at an angle not exceeding 8°. This 

 limestone is very argillaceous, its solid strata not exceeding seven feet in thickness, and even these 

 are divided into seven beds, which are covered by a considerable mass of valueless shale with small 



1 The masses of limestone nearest to Wallsall are usually covered by gravel. 



2 It is difficult to avoid expressing surprise, that in this part of England persons should be found so utterly 

 ignorant of the geological succession of the strata, as to sink for coal beneath the Wenlock or Dudley shale. 

 Recent trial shafts (failures of course) have been made at Delves Green, and exhibit on their sides mounds of 

 shale, charged with fossils of the Wenlock formation. These mistakes occur simply through inattention to the 

 organic remains, with which indeed few practical miners are acquainted. Hence the endless follies we now 

 hear of, such as sinking for coal at Northampton through the inferior oolite, where it is demonstrable, that 

 the unfortunate speculators can scarcely penetrate even the lias formation. Black, bituminous and pyritous 

 shales, resembling beds of the coal formation, are quite enough to lead any common miner to believe that he 

 "smells" the coal, and thus country gentlemen are duped by ignorant men, who often honestly believe what they 

 prophesy. Whether the strata thus resembling coal measures, be a mile above or below the geological position 

 of the carboniferous system, has never formed part of the education of these speculators. (See observations, 

 pp. 328 and 411, note.) 



