92 



PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. 



3. Dlctyonema-shales. — The Black Shales are overlain by some 

 pale greenish and light piu'plish shales containing Dldyonema socialis, 

 which occupy a small triangular area at the extreme south-west of 

 the district near Hayes Copse, and which are covered up on the 

 south by the Permian breccia of Bromesberrow Park, and on the 

 west by the May Hill Sandstones of Howler's Heath. The occurrence 

 of these Dictyonema-shales in this situation is a matter of much 

 interest, as their position in Forth Wales is known to be immediately 

 above the Upper Lingula-beds ; and taking this circumstance in con- 

 nexion with the general facies of the fossil fauna of the Black Shales 

 and HoUj^bush Sandstone, we may, I think, regard the former as the 

 representatives of the upper division of the Lingula-beds, and the 

 latter of the middle division of the same series ; the lower division, 

 or that characterized by Lingulella Davisii, being either covered up 

 or absent. 



The overlapping of the beds, which was mentioned in speaking of 

 the Hollybush Sandstone in its minor subdivisions, is observable also 

 between the sandstone and the Black Shales. On the western slopes 

 of the Keys End Hill the shales rest directly on the crystalline rocks, 

 but in the Valley of the \\Tiite-leaved Oak they begin to be separated 

 from the metamorphic rocks of the Eagged-stone Hill by the Holly- 

 bush Sandstone ; and, proceeding northwards, they open out, exposing 

 progressively more and more of the sandstone, until, on the turnpike- 

 road as it emerges from the Hollybush Pass, they are nearly 600 feet 

 in thickness*, but north of the turnpike-road they again close in 

 slightly upon the hills. Not only is there unconformability between 

 the sandstone and shales, but also between the different members of 

 the sandstone itself, — an unconformabihty which is due to overlap 

 produced by subsidence of the sea-bed during the period the sand- 

 stones and shales were Jseing deposited. 



4. Altered Rocks on the East of the Herefordshire Beacon. — To the 

 east and south-east of the Herefordshire Beacon there is a small area 

 occupied by baked rocks of the probable age of the Hollybush 

 Sandstone and Black Shales, but in which the bedding is so nearly 

 effaced that it is not possible to determine the order of superposition 

 with certainty ; they are therefore considered together. 



Fig. 6. — Section across the Southern extremitij of the British Gamp 

 {Herefordshire Beacon'). 



Fault. Fault. E. 



/ e 



a. Trias. 



d. Lower Ludlow rock 



e. Wenlock Limestone. 



/. Wenlock shale. 



h. Altered Primordial rocks with trap-dykes. 



i. Metamorphic rocks. 



* Prof. Pliillips, op. vit. p. 51. 



