Vol. 65.] 



GEOLOGY OF THE NEIGHBOURHOOD OF SEAFOED. 



453 



is, that while the beds have been transversely folded on one side of 

 the fault-line, they remain normal on the other side. I have 

 represented this feature in the accompanying diagram (fig. 6). We 

 may have here, tberefore, an example of a fault with a variable 

 throw, such as is described by Green in his well-known text-book, 1 

 without reference, however, to an actual example ; nor can I recall 

 any description of a similar fault, although such doubtless exist. 



Eig. 6. — Diagram illustrating the fault in the Cuckmere Valley. 



The variability of the throw of this fault would explain why its 

 presence is not more in evidence in the cliff- section, and Mr. C. 

 Davies Sherborn's rendering of the appearance of the strata in the 

 cliff is in no way invalidated by this hypothesis, although it gives 

 a false impression of a north-and-south undulation instead of the 

 east-and-west flexure now shown to exist. 2 



In order to understand the full significance of the Seaford 

 flexure, it will be well to consider next what place it occupies in 

 the general system of folds comprehended in the Wealden uplift ; 

 for which purpose I have indicated on a map the locality and 

 strike of the more important flexures, especially those at present 

 known on the south of the main anticlinal axis (fig. 7, p. 454). 

 They have been aptly described as ripples on the wave of general 

 upheaval to which the Wealden anticline is due. Details respecting 

 these have been so fully described by Topley, 3 Dr. Strahan, 4 and 

 Mr. Clement Reid 5 that they need not be repeated here. Many of 

 them are quite minor flexures, and from my own experience in 

 the Wealden area, they are often merely gentle symmetrical folds, 



1 ' Physical Geology ' 2nd ed. (1883) p. 368. 



2 See pi. ix, Proc. Geol. Assoc, vol. xvi (1900). It should be remembered 

 that the line of this section is not straight, as the coast-line deviates north- 

 wards below Seaford Head. It is this deviation alone which exposes the 

 apparent westerly dip of the beds. 



a ' Geologv of the Weald ' Mem. Geol. Surv. 1875, pp. 277, 278. 



4 ' Geology of the Isle of Wight ' 2nd ed. (1889) p. 239 ; also ' Guide to 

 the Geological Model of the Isle of Purbeck ' Mem. Geol. Surv. 1906, p. 5. 



5 ' Geology of the Country near Chichester ' Mem. Geol. Surv. 1903 (Expl. 

 of Sheet 317) p. 2. 



Q.J.G.S. No. 259. 2h 



