552 RECENT. 



jasper give employment to lapidaries. '^ Between Torquay and Teignmouth Lime- 

 stone-peljbles with Devonian Madrepores are picked up. (See p. 237.) The Isle 

 of Wight and Brighton pebbles consist chiefly of chalcedonic Chalk-flints 

 containing the Sponge Siphonia ( C/ioatii/es) Koeiiigi and much hydrous peroxide 

 of iron. (See p. 416.) At Eastbourne, also, many flint-pebbles are collected for 

 sale.^ 



The travelling of shingle beaches is promoted by wind-waves 

 and influenced by the set of the tides and currents, and by the 

 configuration of the coast,^ and there is not unfrequently a conflict 

 between the sea and a river. The results necessarily depend upon 

 the general power of each agent. Usually the breakers gain, so 

 as to produce a long line of shingle, turning the course of the 

 river, until the latter obtains support from a hard cliff", and is no 

 longer forced aside, or the river perhaps percolates through the 

 shingle. Such is the case along the southern coast of Devon 

 between Exmouth and Axmouth. 



There is a noteworthy 'Pebble Ridge' at Northam Burrows (Appledore), in 

 Barnstaple Bay, derived from the Culm-measures of Hartland Point, etc.* 



On the Suffolk coast the Orford beach is a remarkable one : the general direction 

 is south-west, and it has diverted the river Ore or Aide about ten miles to the 

 south. ^ In the time of Henry VIII. the mouth of the river was opposite Orford 

 Castle ; these changes have been brought about by the alteration of the coast-line 

 and the destruction of land. (See sequel, regarding Dunwich.) At Weybourn, 

 in Norfolk, there is a beach extending westwards to the mouth of Blakeney 

 Harbour. 



There is much shingle stretching from Sandwich northwards to Pegwell Bay. 

 To the south-west, the shingle about Romney Marsh, including Dunge Ness 

 Beach, is three miles long and one to four miles wide, and formed of pebbles 

 which have come from the west. It is heaped up in "fulls" or ridges, which 

 mark old high-water levels. Romney Marsh was originally a sandy bay; there 

 used to be a harbour at the foot of Lympne Hill, and ships have sailed along the 

 river Rother (anciently Limen), past Appledore." The shingle at Lydd was 

 probably the shore-line in Roman times ; since then the shingle-point has advanced 

 towards the south-east, four miles seawards, in a direct line. 



At Hengistbury Head a shingle bank one mile in length was formed in 20 years, 

 and has since been increasing at an annual rate of about 40 yards.^ 



CJicsil Ba)ik. — K continuous bank of shingle extends from Bridport Harbour and 

 Burton Bradstock to Portland. It varies from 170 yards wide and 22 feet high near 

 Abbotsbury to 200 yards wide and 42 feet high at Portland. From Burton Brad- 

 stock to Abbotsbury it touches the sliore, but eastwards, for upwards of ten miles, 

 it is separated from the land by the Fleet, and to this portion the name Chesil 

 Bank is now generally restricted. The pebbles increase in size eastwards from 

 sand and fine shingle at the western extremity of the beach, to pebbles three to four 



1 W. Keeping, G. Mag. 1882, p. 256. 



- Rev. A. N. Malan, Nat. Hist. Notes, iii. 112. Moss-agates have not been 

 found in England and Wales, although they occur in Scotland : they are varieties 

 of chalcedony enclosing moss-like forms of oxide of manganese and iron, and green 

 earthy chlorite. On the subject of quartz pebbles, which when rubbed together 

 give an electric spark, see C. Tomlinson, P. Geol. Assoc, i. 243. 



3 De la Beche, Geol. Manual, p. 73 ; H. R. Palmer, Phil. Trans. 1834, p. 567. 



* Pengelly, Trans. Devon Assoc. 1868 ; Sedgwick and Murchison, Proc. G. S. 

 ii. 442. 



* J. B. Redman, Proc. Inst. Civ. Eng. xxiii. 191 ; Whitaker, Geol. Ipswich, 

 p. 98. 



^ F. Drew, Geol. Folkestone, etc. (Geol. Surv.), p. lb. 

 ■^ T. Codrington, G. Mag. 1870, p. 23. 



