612 DR. G. J. HINDE AND ME. HOWARD FOX OX [XoV. 1895, 



white and porcellanous, resembling a kind of china-stone, it is 

 evident that these authors are referring to the distinguishing 

 features of the Codden Hill Beds, though these are not specially 

 designated. 



Although De la Beche 1 gives a section of the lower beds of the 

 Culm and points out that on the northern boundarj'' there is no 

 evidence of unconformity with the Devonian beds below, but a 

 gradual passage from them into black carbonaceous slates and 

 limestones with Posidonomyce, he does not distinguish the Codden 

 Hill Beds, though possibly they are included in the ' shales and 

 slates occasionally carbonaceous, mingled with some grits,' which 

 he says succeed the Posidonomya-heds. 



The first record of the Codden Hill Beds appears in a paper read 

 to this Society by the Bev. D. Williams 2 in April 1839, in which 

 they form part of the No. 8 of this author's subdivision of the 

 Grauwacke Series. The Codden Hill Grits, as he terms the beds, 

 are divided into grits, limestones, and dark slates. The grits are 

 stated to be lithologically distinct from any other strata in the 

 country, they are slightly calcareous, fine-grained, flinty, thin- 

 bedded, and dark-coloured, but often striped of different tints, and 

 when decomposed resemble hard chalk. The grits are associated 

 with large insulated masses of dark limestone, alternating with 

 black shales containing Goniatites and Posidonomyce, and below 

 these are dark slates which gradually pass into the Trilobite Shales 

 of the Devonian. 



In a subsequent paper which appears to have been privately 

 printed, entitled ' Tabular Synopsis in descending order of the 

 Succession of the several Members of the Devonian System, as 

 developed in W. Somerset, Devon, and Cornwall,' Mr. Williams 

 further subdivides the Codden Hill Grit into the following four 

 groups in descending order : (i) Black, dark, and smoky-grey schists, 

 flags and roofing-slates containing some plants ; (Jc) Flint and 

 jasper rock; (Z) Black-layered, fine-grained grit, almost a lydian- 

 stone, containing a few Crinoidea ; (m) Posidonia-limestone and 

 culmy shales ; and the thickness of the whole series is estimated at 

 1500 to 2000 feet. It is to the divisions Tc and I that our Badio- 

 larian Beds belong. 



Prof. John Phillips in 1841 3 pointed out that the base of the 

 carbonaceous group in North Devon consisted of black shales and 

 limestones, with Posidonice and Goniatites, exposed at Venn, Swim- 

 bridge, and Bampton, which are overlain by the Codden Hill Beds. 

 These consist of a whitish or grey or black chert in thin striped 

 beds resembling some of the bedded chert of Leyburn in Wensley- 

 dale, associated with very soft, white, arenaceous, and argillaceous 

 layers, which contrast greatly with the black bituminous shales of 



1 'Eeport Geol. Cornwall, Devon, and West, Somerset,' 1839, p. 103. 



2 ' On as much of the Transition or Grauwacke System as is exposed in the 

 Counties of Somerset, Devon, and Cornwall,' Proc. Geol. Soc. vol. iii. p. 115. 



3 'Pal. Fossils of Cornwall, Devon, and West Somerset,' p. 189. 



