Lower 

 Devonian. 



DEVONIAN. 123 



Hangman, Lincombe, and \ Lower Old Red 



Looe Grits. > Sandstone 



Lynton and Meadfoot Beds. ) and Silurian. 



For convenience of description we may arrange our account 

 of the beds in the south-west of England under the following 

 headings : — 



1. North Devon and West Somerset. 



2. Torquay. 



3. Plymouth. 



4. Cornwall. 



I. NORTH DEVON AND WEST SOMERSET. 



In this area the beds are best displayed in the picturesque coast 

 sections between Barnstaple Bay, Lynton, and Minehead. 



The general sequence is clear ; but, owing to the contortions 

 which affect the beds, there are no reliable estimates of their 

 thicknesses, and the figures mentioned must be taken as little more 

 than conjectural. Mr. Ussher has remarked that the Upper 

 Devonian rocks are perhaps from 2000 to 3000 feet thick; the 

 INIiddle Devonian rocks are probably much thicker ; while the 

 base of the Lower Devonian rocks is not seen.^ 



Of late years much has been written about the Devonian rocks. Concerning 

 those in North Devon and West Somerset we are especially indebted to Mr. R. 

 Etheridge,2 Mr. T. M. Hall,^ and Mr. W. A. E. Ussher ;* while Prof. Hull, taking 

 a broad view of the deposits, has submitted tables for classifying and correlating 

 them with other divisions elsewhere.^ 



In North Devon and West Somerset the following series of beds 

 has been determined : — 



( Pilton and Barnstaple Beds. 

 < Brauntoi 



( Pilton Beds < Braunton Beds 

 Upper ) ( Croyde Beds. 



Devonian ) Baggy and Marvvood Beds. 

 ( Pickwell Down Sandstones. 

 Middle i Morte Slates. 

 Devonian \ llfracombe Beds. 



T ( Hangman Grits. 



Lower ) j ° e-i ^ 

 ,, ■ < Lynton Slates. 



Devonian J t- , ,0 j ^ 



( t'oreland Sandstones. 



The diagram (Fig. 17, p. 114) is intended to give a general view of the 

 relations of the strata, and it is based on sections by Mr. A. Champernowne and 

 Mr. W. A. E. Ussher.« 



^ P. Geol. Assoc, viii. 443. 



• Q.J. xxiii. 568. 

 3 Q.J. xxiii. 371. 



* Proc. Somerset Arch. Soc. xxv ; Geol. Mag. iSSi, p. 441. 

 ^ Q. J. xxxviii. 255. 



« Q. J. XXXV. 534, 540. 



