A HISTORY OF DEVONSHIRE 



Lynn valley, on the north side of which, near Oare (in west Somerset), 

 a patch of Lynton beds rests upon them. 



The Lynton beds consist of bluish-grey irregular slates, partly 

 calcareous and interstratified with even bedded grits ; they contain 

 decomposed brown patches with fossil casts. Slates and grits of similar 

 character occur in the Meadfoot beds with which the Lynton beds are 

 homotaxeous. Amongst the badly preserved fossils recorded from these 

 beds Valpy' mentions Tentaculites scalaris, and numerous casts of 

 Megalodon cucullatum as occurring at Woodabay, and Kayser " obtained 

 Spirifer hystericus and Chonetes sarcimlata in the Valley of Rocks, Lynton. 

 The Lynton beds pass under the Hangman group, the boundary runs 

 from the coast through Martinhoc, to the south of Barbrick Mill and 

 by Farley, crossing the Somerset boundary rather' more than a mile 

 south of Malmsmead. 



The Hangman grits consist of brownish, green, bufF and, locally, 

 purplish-red mudstones and slates with grits and flaggy sandstones (the 

 Trentishoe beds). Grits are prevalent in the upper beds, which contain 

 types met with in the Staddon grits. Natica and Myalina have been 

 found in red grits in the upper part of the series. They are homotaxeous 

 with the Staddon grits, but it does not necessarily follow that they may 

 not be in part of Eifelian age. Stringocephalus burtini has been found in 

 the slates with grit beds which overlie them in West Challacombe Bay 

 and form the base of the Ilfracombe slates. The boundary runs on the 

 north of Holstone and Parracombe to Oare Oak on the county 

 boundary. 



Middle Devonian. — The Ilfracombe slates are dull grey and silver 

 grey with occasional seams, lenticles and beds of limestone, and with 

 intercalated grits toward their base. The calcareous beds contain a 

 characteristic Middle Devonian fauna. Valpy records however Renssel- 

 Iceria strigiceps, Tentaculites scalaris, and in his general list gives Stegano- 

 dictyum cornubicum (of McCoy — now recognized as Pteraspis) and 

 Rhynchonella cuboides (more probably R. procuboides) with such character- 

 istic Middle Devonian forms as Cystiphyllum vesiculosum, Heliolites porosus 

 and Stringocephalus burtini. In the Lynton railway cuttings no boundary 

 could be drawn between the Ilfracombe slates and the Morte slates. 



Morte Slates. — ^The lower beds of the Morte slates contain hard 

 brown siliceous bands, and are succeeded by hard greenish slates and 

 slaty mudstones. On the coast the slates make jagged reefs and are 

 intersected by quartz veins. Gritty beds occur in the lower portion 

 at Slade and Flat Point ; these were regarded by Hicks as a repetition 

 of the lower, or Challacombe Bay, beds of the Ilfracombe group, the 

 iiTi'ervening beds being treated as a syncline. Valpy was informed by 

 a workman that fossil casts had been found at Slade. Hicks' fault 

 boundaries have not been discovered by the upholders of the normal 

 sequence, but, in view of the Lower Devonian age claimed for the 



» Votes on the Geobgj of Ilfracombe and the Neighbourhood (Twiss & Sons, Ilfracombe. Not dated). 

 * Neu Johrb.fur Mineralo^e (1889), vol. i. p. 182. 



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