104 T. Davidson S^ G. Maw — TT. Silurian Rocks of Shropshire. 



between the Wenlock Limestone and the Wenlock Shale, the re- 

 mainder of the shale may be subdivided as follows : — 



Barren Shales of Coalbrook Dale and Ape Dale, or " Coalbrook 



Bale Beds " 1100 to 1200 feet 



Fossiliferous zone of Buildwas, or " Huildwas Beds " 80 to 100 ,, 



BaTTen Shales oiBnMvra.s 'Pavk, or " Basement Beds ^' 500 to 600 ,, 



These soft shales have largely determined the configuration of 

 the contours of the district, and represent the sweeping Ape Dale 

 valley of denudation, which spreads out for twenty miles below 

 the supporting ridge of Wenlock Limestone of Wenlock Edge, and 

 have in Coalbrook Dale yielded to the excavation of that picturesque 

 valley. 



Some soft shales, about 100 feet thick, overlying the Wenlock 

 Limestone, and exposed in cuttings by the side of the railway 

 between Buildwas and Wenlock, west of the Bradley Lime Quarries, 

 may also pertain to the Wenlock series : in physical character they 

 more nearly resemble the shales of the Wenlock than the overlying 

 Ludlow Beds. 



The Wenlock Shale in Shropshire, which cannot be much less 

 than 1800 to 1900 feet in thickness, has a development much in 

 excess of the Wenlock shale in the Malvern district, where Professor 

 Phillips estimated it to be 640 feet thick ; indeed, its thickness in 

 Shropshire is greater than in any other district, unless we except 

 its supposed equivalents, the Denbighshire Flags, which Mr. Gr. 

 Maw believes will be found to belong to a distinctly lower horizon. 



The Ludlow Series. — Any definite estimate of the relative thick- 

 nesses of the several members of the Ludlow Beds is difficult to 

 arrive at, as at the eastern extremity of the Shropshire escarpment 

 the Aymestry horizon is ill-defined, here and there represented by 

 isolated thin bands of limestone, and again as thick masses of 

 impure concretionary limestone intermixed with shale. Collectively 

 the Ludlow series attains a thickness of from 1200 to 1400 feet, 

 which the Aymestry band divides nearly equally, the Lower 

 Ludlow being a little thicker than the Upper, and consists of softer 

 shales. The Upper Ludlow Beds, as at Burton, near Wenlock, 

 often assume the character of fissile Tile-stones, The Lower 

 Ludlow Beds are exposed in cuttings of the Wenlock Railway 

 between Wenlock and Presthope, and the very base of these beds 

 are seen in the Wenlock Railway east of Wenlock. The equivalent 

 of the Aymestry Limestone is finally exjoosed in the road-cutting 

 below the Dunge House, near Broseley, and to the west of the 

 Marsh Farm on the high road between Broseley and Much Wenlock. 

 The Upper Ludlow is to be seen by the road-side at Burton, near 

 Wenlock, and is also exposed in Willey Park, and in the bottom of 

 the valley below the Dean Farm, near Broseley. 



The beds connecting the Upper Ludlow with the Old Eed Sand- 

 stone, which are well exposed on the banks of a little stream known 

 as Linley Brook, two or three miles south of Broseley, have been 

 described by Messrs. Roberts and Randall in the Quarterly Journal 



