South-western Coal District of England. 281 



highly inclined beds of slaty micaceous sandstone^ alternating with and passing 

 intOj on the one hand^ a coarse breccia having grains as large as peas ; on 

 the other, a soft argillaceous slate. It contains occasionally subordinate beds 

 of granular glassy quartz-rock, but its general aspect is that of a coarse grey 

 sandstone, resembling one of the siliceous coal-grits. 



These varieties of grey-wacke occur on the north-eastern border of the 

 Forest, near the southern extremity of the chain of transition limestone, which 

 we have before described as extending from Stoke Edith, near Hereford, to 

 Flaxley on the Severn. They are here connected with the transition lime- 

 stone, and occupy a very limited tract, constituting the central and most ele- 

 vated portion of an insulated hill, called May-hill, which rises 965 feet above 

 the sea, and extends in length from N. to S. about 1^ mile, and about | of 

 a mile in breadth. The southern extremity of this hill is traversed by a defile 

 through which winds the road from Gloucester to Ross. The abruptness of 

 this pass is sufficient to give it a wild and mountainous character, and affords 

 the best opportunity of examining the varieties of the rock. 



2. Transition limestone. 



The lower beds of this formation, which lie between the granular strata of 

 grey-wacke just described, and those of the rock to which the term transition 

 limestone is strictly applicable, consist of fine-grained, tender, extremely ar- 

 gillaceous slate, loose in texture, and assuming imperfectly the character 

 of grey-wacke slate. This shale is commonly known in the district by the 

 name of water-stone, in consequence of the wet soil that is found wherever 

 it appears at the surface. In its most compact form it scarcely differs from 

 common grey-wacke slate, between the water-stone and which it is as difficult 

 to draw a line of separation, as it is between the grey-wacke slate and primi- 

 tive clay-slate. The water-stone is never sufficiently strong to be used as 

 roofing slate, and instead of being tinted with blue or purple like the older 

 and harder slates, it is commonly of a muddy green colour, approaching to 

 brown. Calcareous matter is interspersed in it but sparingly, and it alter- 

 nates occasionally with subordinate beds of fine-grained sandy flag-stone and 

 porous sandy slate. 



The occurrence of this water-stone is by no means limited to the ridge of 

 hills extending from May-hill to the neighbourhood of Hereford ; it forms also 

 a considerable part of tliat range which stretches on the west of the Malvern 

 Hills from Ledbury to Abberley, and which has been described by Mr. Horner 

 in the 1st volume of the Geological Transactions. In Shropshire, it occu- 

 pies the valley between the long and parallel ranges of Wenlock-edge and 

 Caer-Caradoc, the former consisting of transition limestone, the latter on its 



2o 2 



