344 ME. C. REID ON THE PLEISTOCENE 



20. The Pleistocene Deposits of the Sussex Coast, and theie 

 Equivalents in Othee Disteicts. By Clement Reid, Esq., 

 P.L.S., F.G.S. (Eead February 24th, 1892.) 



[Oommunicatedbj permission of the Director-General of the Geological Survey.] 



The geological survey of the district lying between the South 

 Downs and the Sussex coast has been completed,, but the time needed 

 for finishing and engraving the maps will make it impossible to 

 publish a memoir for several years to come. It seems advisable, 

 therefore, to bring before this Society an outline of the general 

 results obtained, especially as certain of these results may seriously 

 modify our views as to the succession of the deposits, and also as to 

 the climatic changes in late Tertiary times in the South of England. 

 A previous communication, published in this Journal,^ dealt with the 

 question of the origin of the Coombe Rock and of dry Chalk valleys ; 

 I now propose to continue this work by showing the relation of the 

 Coombe Eock to the various Pleistocene strata which occupy the 

 plain lying between the southern edge of the Downs and the sea. 

 I propose also to indicate briefly the probable correlation of these 

 strata with the glacial deposits of other parts of England. 



The literature of the subject is somewhat extensive, for many 

 good observers have examined the deposits between Brighton and 

 Selsey Bill, especially the ' Pagham erratics,' the ' mud-deposit ' of 

 Selsey, and the Brighton ' elephant-bed.' It will scarcely be 

 necessary here to speak of the whole of the writings relating to the 

 district, but certain important memoirs and original observations 

 must be referred to ; otherwise it would be impossible to show in 

 what respect the recently completed Survey supplements our previous 

 knowledge of the subject, or obliges us to modify preconceived ideas. 

 The following abstract has been prepared, therefore, to show what 

 were the accepted views as to the succession of the deposits, in the 

 year 1884, when the Drift Survey of the Sussex coast was commenced. 



Mantell, in 1822, in his ' Possils of the South Downs,' mentioned 

 that the mamraaliferous Coombe Pock of Brighton was underlain 

 by an ancient beach-deposit, containing sea-shells and waterwoni 

 erratic blocks of granite, &c. 



The first edition of Dixon's 'Geology of Sussex,' published in 

 1850, alluded to the erratic blocks found on the shore near Selsey, 

 and suggested their probable transportation by glaciers. The 

 author also alluded to the deposits containing Elephas primigenius 

 and southern marine moUusca at Selsey, but in his description there 

 is a great deal of confusion between the true Pleistocene strata 

 and the recent estuarine deposits. Dixon correctly correlated 

 certain ancient beach-deposits near Worthing with the Paised Beach 

 at Brighton, though at the same time he did not clearly distinguish 

 between the Coombe Pock and the underlying marine strata. The 



1 Quart. Jni^n. Geol. Soc. vol. xliii. (1887) p. 364. 



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