600 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



they were not accumulated in a deep sea ; and this continued de- 

 pression and great development of organic limestones and slates, 

 rich in Coelenterata and Brachiopoda, were continued through and 

 during the accumulation of the whole of the Ilfracomhe group, being 

 followed by the deposition of the fine-grained, smooth, grey, glossy, 

 unfossiliferous slates of Lee, EocTiham, Mortehoe, and Winsford (in- 

 land), in which as yet no traces whatever of organic remains have been 

 found. They bear all the evidence of deep-sea accumulation. 



Fig. 8. — Section at Heddon's Mouth. 



Lower Devonian slates. 



Hangman sandstones. 



4. Conclusions relative to the Lower Devonian Series of West Somer- 

 set and the Lynton area Sfc. — (1) That the great series of the Pore- 

 land red sandstones and grits forming the northern part of the 

 area under description is nowhere (from the Quantock Hills on the 

 east, to the Eoreland on the west) seen in its entire thickness, neither 

 the base nor upper portions being clearly visible. The anticlinal in 

 the Valley of the Ljnin, nowhere along its line of elevation dis- 

 closes this, being concealed either by the overlying Lower De- 

 vonian slates, which are conformable to its southern dip, after 

 crossing the anticlinal, or by faulting along the course of the anti- 

 clinal also. 



(2) That the great series of red and grey sandstone and grits con- 

 stituting the base of all the North Devon and West Somerset 

 deposits is the oldest of the Palaeozoic series exposed in that area, 

 and that its mass is greatest from Dunster and Wooton Courtney 

 on the south to the northern and precipitous escarpment of North 

 Hill on the north, overhanging the Bristol Channel, where it is 

 believed we have higher beds than are exposed along the Porlock, 

 Culbone, and Poreland range. An extensive fault and undulation 

 of the strata along North Hill, as exhibited at Hurlstone and Green - 

 lay Points, may, however, modify this apparent thickness, though 

 the strike of the beds seaward and north of the Poreland series 

 would indicate the position of higher beds. 



(3) The dip is much greater on the northern side of the anticlinal 

 than on the southern (a mean of fourteen observations along the 

 strike for 13 miles determining it to be 34°), and the beds are much 

 more disturbed. No organic remains are known to occur in these 

 Lower Bed Sandstones. 



