594 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



age in South Devon*, a significant and important fact as bearing 

 upon the physical structure and stratigraphical position of the rocks 

 of West Somerset. 



10. Goldsoncot. — On the strike of the same lower calcareous zone 

 at Goldsoncot Farm quarry is another fine exposure of red, purple, and 

 grey- veined variegated limestone in thick beds ; a band about twenty 

 feet thick occurs here, and is succeeded by others interstratified with 

 the purple slates and indurated shaly and marly beds ; the limestone 

 is encrinital, containing also many corals, Cyatliopliyllum ccespitosum, 

 Favosites cervicornis, Stromatoporci and others resembling those from 

 the Withycombe series ; but the rock was too crystalline for me to 

 be certain as to other species. The beds dip north -north-east 20°. 



11. Higher Roadivater, Traphole, and Lod Huish. — The same zone 

 of limestone and its associated slates and corals here regularly dip 

 south and south-east 30° ; the beds are massive and thick in places, 

 but lumpy, or in hummocks, and lenticularly arranged in the slates. 

 The corals, which are less abundant than at either Goldsoncot or 

 Withycombe, can nevertheless be detected, on close examination, 

 directly east of Koadwater ; and higher in the series are the well- 

 known quarries and limestones of Lod Huish and Nettlecombe. 

 Upwards of 1000 feet of slates intervene between these two cal- 

 careous belts ; and viewing this Huish and ISTettlecombe group as 

 one series of associated limestones and shales, it also cannot be 

 less than 1400 feet thick. The following section will show their 

 relative position. 



Pig. 6. — Section from Croydon Hill to Yard. 



Crovdon Hill 



a, New Red Conglomerate, b. 



Middle Devonian slates, with intercalated 

 limestone (c). 



lY. Stefcture and Succession of the koce:s of North Devon. 

 A. Lower Devonian Group. 



1. Porloch to Lynton. — The grand range of hills which at thi'ee 

 points of the compass immediately surrounds the Porlock Yalley, is 

 apparently composed of one group of sandstones, all from the latitude 

 of the Foreland, Countesbury, Oare, and Porlock Hills, dipping north- 

 east, or towards the Bristol Channel. The same may be said of 

 North Hill and Grabbist Hill to the east, which are cut off or sepa- 

 rated from Croydon and Luccott HiUs, and Dunkerry Eeacon to the 



* Mr. Perceval has presented a complete series of the species to the Museum 

 of Practical Geology, Jermyn Street. I obtained several specimens from the 

 same locality. 



