156 Henry Dewey — Raised Beach of North Devon. 



Cornwall and South Devon. 



The striking resemblance between these beds and those of North 

 Cornwall led me to re-examine a fine section at Trebetheric Point, 

 opposite Padstow. At this locality a thick bed of boulders consisting 

 of quartz, greenstone, elvan, quartzite, flint, and hard grit rests 

 partly on ' head ' and partly on, and in hollows in, the cemented 

 sands. The sands contain marine fossils such as limpet, mussel, and 

 crab. While the underlying beach is preserved in patches only, the 

 raised beach platform is conspicuous in the adjoining bay and on 

 both sides of the estuary of the River Camel. The sequence of 

 deposits is identical with those in North Devon, and persists in some 

 degree all round the coasts of Cornwall and South Devon. The 

 raised beaches of the West of England were admirably described by 

 Ussher and others, so that further description is not necessary. It 

 should, though, be mentioned that Reid^ discovered an important 

 section of raised beach at 65 feet above O.D. This is in Penlee 

 Quarry, near Mousehole, on the east of Land's End. 



Mr. Barrow " also made an important discovery in the Isles of 

 Scilly, where a bed of glacially striated stones overlies ' head ' and 

 raised beach. And, what is of even greater consequence, he correlated 

 this glacial deposit with the ' Limon ' or Loess of the coast of 

 Brittany, pointing out the identity of the succession seen in Brittany 

 and Cornwall. This is important in relation to the question of 

 the age of the raised beach, for, as will presently be shown, the 

 'Loess' ranges from St. Acheul to Le Moustier in the Palaeolithic 

 Series. From the accounts given it is evident that the same sequence 

 of deposition occurred along the coasts of the whole of Cornwall 

 and Devon. Moreover, it includes deposits formed under varying 

 climatic conditions ranging from cold, if not Arctic, at the com- 

 mencement of the raised beach phase, through warm temperate, 

 when the sands were deposited, to a second cold period whose 

 incoming is marked by the ' head ' and its maximum by the bed of 

 striated stones. Such faunal evidence as we possess confirms this 

 order of events. 



Glamorgan and Southern Ireland. 



We may next inquire how far this sequence extended into 

 neighbouring regions, namely Glamorgan and Southern Ireland on 

 the one hand and the south coast of England on the other. To take 

 Glamorgan first, we know from the observations of Prestwich,^ 

 Falconer,^ Tiddeman,* Strahan,= and Leach ^ that the deposits over- 

 lying the raised beach in Glamorganshire are in descending order — 



Recent head. 



Boulder-clay. 



Ancient head. 



Blown sand (often cemented into sand-rock), with breccia. 



Raised beach, with erratics. 



' Geology of the Land's End (Mem. Geol. Surv.), p. 75. 

 ^ Geology of the Isles of Scilly (Mem. Geol. Surv.), pp. 21-31. 

 ' Quart. Journ. Geol. Soc, vol. xlviii, p. 263, 1892. 

 ■* Rep. Brit. Assoc, 1900, p. 760. 



^ Geology of South Wales Coalfield (Mem. Geol. Sui-v.), pt. viii, p. 127, 1907. 

 Geol. Mag., 1911, p. 462. 



