115 



rocks," and " Wenlock limestone."* As, however, these rocks rise up irregu- 

 larly, like separate islands, through the surrounding coal measures, and not in 

 their regular order of superposition, so it was obviously impracticable to have 

 determined their relative age by any local evidences ; and hence no attempts 

 could have been made to distinguish the younger from the older deposits, until the 

 structure and organic remains of the different members of the Silurian system had 

 been fairly worked out in other districts, where these types were fully and clearly 

 displayed in their regular order. 



2. Ludlow rocks. — These rocks appear at the surface in three detached 

 points in this coal-field, viz., Sedgeley, Turner's Hill, and the Hayes. At Sedge- 

 ley they are thrown up in an elongated ellipse, very much resembling a large 

 inverted ship, of which Sedgeley Beacon, 630 feet above the sea, may be consider- 

 ed as the keel. The upper Ludlow rock, though not thick, is plainly marked by 

 containing the Laptcena lata, the Serpula gigantea, &c, and by overlying a 

 limestone which is in every respect identical with that of Aymestrey or the middle 

 member of the Ludlow rocks, presenting the same lithological structure, i. e. a 

 dull argillaceous grey limestone, which among other well-known shells, such as 

 the Terebratula Wilsoni and the Lingula, contains also the beautiful Pentame- 

 rus Knightii so entirely peculiar to this stratum. As at Ludlow and Aymestrey, 

 this limestone of Sedgeley, known here as the " black limestone," forms an excel- 

 lent cement under water. 



Turner's Hill, a small elevation between Gornals and Himley, is composed of 

 Ludlow rocks ; and the Hayes is a narrow short tongue of the same, with a cen- 

 tral baud of limestone, which rises at a high angle from beneath the coal mea» 

 sures, on the main road from Stourbridge to Hales Owen, a portion of the lower. 

 Ludlow rock being also well exposed. 



2a. Wenlock limestone. — This limestone formation is much more largely 

 developed than that of the Ludlow rocks, constituting several ellipsoidal masses 

 near the town of Dudley, which have been long worked and extensively known 

 among collectors, from the number and beauty of their organic remains. Hence 

 the rock has been usually termed the " Dudley limestone." As, however, it was 

 impossible to have ascertained in this district the relative age of these rocks, their 

 different members being independently in contact with the coal measures, the nor 

 menclature of the Silurian system already selected is adhered to, because in 

 Shropshire the Wenlock limestone, in its fullest standard, rises out regularly from 

 beneath the Ludlow rocks, and the latter passing beneath the old red sandstone 

 and carboniferous limestone (both of which are wanting at Dudley) complete the 

 proofs required. The author, therefore, entreats geologists not to employ the 



* There is one spot, however, within the author's knowledge where the underground 

 works reached a thick mass of red shale or marl beneath the coal-field ; but the works hav-. 

 ing been long abandoned, no correct knowledge of these red rocks can be now obtained. 



q2 



