554 PLEISTOCENE AND RECENT. 



Some of our Raised Beaches may be connected with oscillations 

 that occurred in the Glacial period. (See p. 481.) Long ago, in 

 describing the raised marine beds on the Devon coast, and com- 

 menting upon the paucity of the INIolluscan remains contained in 

 them, INIr. Godwin-Austen suggested that the period of these raised 

 deposits may have been one less favourable than the present to the 

 development of marine life, owing, perhaps, to a lower tempera- 

 ture.^ 



Many Raised Beaches have probably been destroyed in recent 

 times, owing to the destruction of clifis composed of the softer 

 strata, for it will be observed that most of these beaches repose on 

 hard rocks. Some instances formerly regarded as " ancient marine 

 terraces" are now known to be "lynchets" or terraces of cultivation, 

 etc.' (See sequel.) 



Raised Beaches are not uncommon along the coasts of Devon and Cornwall, 

 occurring at Hope's Nose and the Thatcher Stone near Torquay, Slapton, the Hoe 

 at Plymouth,^ St. Blazey Bay (Polkerris), Falmouth Bay, TheNare, Coverack Cove 

 (flints), in and near Mount's Bay, Cape Cornwall, St. Ives Bay, Towan Head, 

 near Trevose Head, near Pentire Point, and Barnstaple* extending from Braunton 

 Burrows to Baggy Point. 



Holes considered to be bored by Pholas have been noticed in the Devonian 

 Limestone at Petitor, Babbacome, and near Kent's Cavern, Torquay, at heights of 

 200 feet and upwards above sea-level.^ 



Raised beaches occur at Weston-super-Mare, at Rhos Sili Bay, Gower, and the 

 Mumbles, near Swansea. On the Dorsetshire coast the Raised Beach at Portland 

 Bill is well known, shells occur on the eastern portion of the beach, which attains 

 an elevation of from 25 to over 50 feet.^ There are also Raised Beaches at 

 Portsdown Hill,'' in Jersey, and at Saltburn (35 feet above high-water mark), 

 on the north-east coast of Yorkshire. 



Among the Pleistocene marine deposits we may include certain 

 beds at Selsea, the Nar Valley, March, Kelsea Hill, and Hessle, 

 which are approximately of the same age, (See p. 481.) 



The deposits at Selsea are as follows :^ — 



Brickearth (probably of subaerial formation). 



Marine clay and yellow clayey gravel, with Boulders. (See p. 495.) 

 Mud-deposit with Littraria rugosa, etc. (Lutraria clay), and Mammalian 

 remains. 



1 T. G. S. (2), vi. 433. See also Q. J. vii. iiS. 



^ See R. Chambers, Ancient Sea-margins, 1S48 ; Mackintosh, Scenery of 

 England and Wales, 1869. 



2 The deposits at the Hoe may be of Alluvial origin, see R. N. Worth, Q. J. 

 xxxii. 236 ; C. Spence Bate, T. Devon Assoc, vii. 150. 



* Sedgwick and Murchison, Proc. G. S. ii. 441 ; Pengelly, Trans. Devon Assoc. 

 1868 ; Ussher, G. Mag. 1879, pp. 166, 203 ; Post-Tertiary Geol. Cornwall, p. 16. 



^ Pengelly, Trans. Devon Assoc. 1S66 ; A. Tylor, Q. J. xxii. 465 ; Mackintosh, 

 G. Mag. 1867, p. 296. 



« Whitaker, G. Mag. 1869, p. 438; W. Gray, P. Geol. Assoc, i. 146; 

 Pengelly, Trans. Devon Assoc. 1870 ; J. C. Mansel-Pleydell, Proc. Dorset Nat. 

 Hist. Soc. i. 2 ; Prestwich, Q. J. xxxi. 29. 



' Prestwich, Q.J. xxviii. 38. 



^ Godwin- Austen, Q. J. xiii. 40; Dixon, Geol. Sussex, ed. 2, p. 82; R. 

 Etheridge, Address Geol. Section Brit. Assoc. 1882; Lyell, Student's Elements, 

 1871, p. 158; A. Bell, Mag. Nat. Hist. July, 1871. 



