452 ] 



warrant such a conclusion. 1 The 

 flexure at Chyngton is too deep 

 and too sharp to enable it to die 

 out completely, within a distance 

 which can scarcely exceed a 

 quarter of a mile. Such an in- 

 terpretation would involve the 

 formation of a cul de sac, 

 which would, I think, be a geolo- 

 gical anomaly. It would, in fact, 

 require as steep and sudden a rise 

 to the east as the existing rise to 

 the south. 



I am disposed, therefore, to 

 favour the second conclusion, 

 that there is a transverse (north- 

 and-south) fault in the Cuckmere 

 Valley (fig. 5). I adopt this 

 view because it seems to be more 

 simple than the other alternative. 

 At the same time, it should be 

 understood that the existence of 

 this fault can only be proved 

 by inference, and I must admit 

 the possibility of the less simple 

 explanation being correct. Such 

 faults are not unknown in con- 

 nexion with the folded Chalk 

 strata of the South Coast. Dr. 

 Straban has described them in 

 connexion with the Purbeck 

 flexure, 2 and Dr. Rowe noticed 

 them in the cliff at Friar's Bay, 

 west of Newhaven. 3 The inter- 

 esting fact in the case of the pre- 

 sumed Cuckmere fault, however, 



1 The pitch of the fold hetween 

 Chyngton and Sea-ford is less than 1°. 

 This is inferred from the difference in 

 level of the base of the Tertiary beds 

 between these points. 'I he same con- 

 clusion is drawn from the approximate 

 horizontality of the zone of Micraster 

 cor-testudinarum in the cliff-section 

 between Cuckmere Haven and Seaford 

 Head. 



2 ' Guide to the Geological Model of 

 the Isle of Purbeck ' Mem. Geol. Surv. 

 1906, p. 7. 



3 Proc. Geol. Assoc, vol. xvi (1899- 

 1900) p. 337. 



