CAMBRIAN ROCKS IN SOUTH SHROPSHIRE. 653 



Salter, in the ' Geological Magazine ' for 1867, refers to the 

 shales at Shineton, which he there regards as " the top of the 

 Llandeilo Flags proper." The same writer seems, in after years, to 

 have been struck with the incongruous association of Cambrian and 

 Cambro-Silurian forms ; for, in ' A Catalogue of the Collection of 

 Cambrian and Silurian fossils contained in the Geological Museum 

 of the University of Cambridge/ published in 1873, while descri- 

 bing what he supposes to be a Triarthrus from Shineton, he suggests, 

 " it is possible that the locality may include some Tremadoc beds." 

 With this exception, geologists have regarded the rocks of the area 

 under consideration as of Caradoc age. 



m 



Object of the Paper. 



I propose to describe the Lower Palaeozoic rocks ranging from 

 near Wellington on the north-east to the May-Hill Sandstone, at 

 Kenley, on the south-west (see map, p. 654). This area is nine miles 

 in length, and two and a quarter miles in its greatest breadth. My 

 description will include an inlier of ancient rocks at Lilleshall, five 

 miles to the north-east of Wellington. I shall pay no attention to rocks 

 newer than the Caradoc, except so far as is necessary for the eluci- 

 dation of my subject. I shall endeavour to prove that the shales at 

 Shineton are of Tremadoc age, and that a part of the so-called 

 " quartzite " between the shales and the Wrekin represents the 

 Hollybush Sandstone of Malvern. I have also satisfied myself that 

 the so-called " greenstone " of the Wrekin and neighbouring areas 

 is largely composed of bedded rocks ; but I defer discussion on this 

 point, and on the quartzites overlying the Wrekin rocks, till I 

 have made further observations. 



Lower Caradoc Rocks. 



Mr. Salter noticed at Harnage and on Cound Brook certain shales 

 containing Trinucleus concentricus, Eaton, Beyrichia complicate^ 

 Salt., DipJograpsvs pristis, His., Orthis testudinaria, Dalm., and 

 other Cambro-Silurian fossils ; and as these shales are very similar 

 in lithological characters to the shales at Shineton, and have the 

 same general strike, both shales were lumped together by him as 

 Lower Caradoc. 



After extensive collections of fossils from all parts of the area 

 under consideration, I arrived at the conclusion that in no case 

 were the Shineton and Harnage fauna? intermixed. I also observed 

 that there was a distinct lithological difference between the two 

 shales, the Shineton shales being more fissile, the Harnage shales 

 more conchoidal, in their fracture. I was greatly puzzled, however, 

 at noticing that, in the Cound-Brook and Harnage area, the shales 

 with a Cambro-Silurian fauna were overlain by utterly unconform- 

 able Caradoc Sandstone, the unconformability in some cases 

 approaching a right angle. At the same time the shales with the 

 older fauna dipped with apparent conf ormability under Caradoc sand- 

 stone. At last I discovered the following section (fig.l), which cleared 



