CHAPTER XXXVI. 

 STAFFORDSHIRE AND WORCESTERSHIRE COAL-FIELDS {continued). 



Upper Silurian Rocks (Ludlow and JVenlocJc formations) support the Dudley and 

 Wolverhampton Coal-Field and rise through it in separate masses. — Lickey 

 Quartz Rock shown to be Caradoc Sandstone, or Lowest Silurian stratum of 

 this district. — Intrusive Trap and altered rocks. — Lines of elevation and dis- 

 location.— Extension of Coal Measures beneath the New Red System. (See 

 Map and PL 37. figs. 1 to 9.) 



We have now to consider the relations of the strata which support the coal measures 

 described in the last chapter. 



These deposits consist of the Upper Silurian rocks or Ludlow and Wenlock forma- 

 tions, which in parts of the field rise from beneath the carboniferous strata without the 

 intervention of any other rocks. They do not, however, appear in their regular order 

 of superposition as in Shropshire, Herefordshire and the South Welsh counties, but 

 form insulated domes or islets ; and hence it would be impossible for any observer who 

 had not studied their position in other districts, to determine which of these formations 

 is the younger 1 . Each of them contains a limestone, the one the black limestone of 

 Sedgeley, the other the well-known rock of Dudley. By consulting their fossil con- 

 tents and unravelling their relations, I have been able to prove that the former repre- 

 sents the limestone of Aymestry or Ludlow, the latter that of Wenlock. 



Ludlow Rocks. 



These rocks appear at three detached points in this coal-field, viz., at Sedgeley and 

 Turner's Hill, near the eastern boundary of the field, and at the Hayes, near its southern 



1 For these reasons therefore it is obvious, that however long known to collectors for the beauty of its organic 

 remains, the name of Dudley limestone could not be used in stratigraphical classification, and hence I was com- 

 pelled to adopt the term of Wenlock. (See Introduction and p. 208.) 



In no previous work has the difference of geological age and position between the limestones of Sedgeley and 

 Dudley been pointed out. They were, indeed, simply considered mineral varieties of the same formation, and 

 Dr. Thomson, in the memoir before referred to, even surmised that they might prove younger than the Old Red 

 Sandstone, because they seemed to be intimately connected with the coal measures. 



