Vol. 56.] ME. P. W. HARMER ON THE CRAG OF ESSEX. 735 



subsidence recorded is that evidenced by the deep borings at 

 Amsterdam, where the base of the Amstelian deposits was not 

 reached at a depth of 1100 feet ; and it died out on the south-west, 

 that is, towards the East Anglian margin of the Crag sea. 1 



This movement of the Pliocene sea-bottom in Holland was 

 coincident with, if not caused by, the accumulation of the sediment 

 brought into it by rivers ; and as the Dutch deposits represent the 

 ancient delta of the Rhine and its affluents, it seems more than 

 probable that the micaceous sands of the ]N"orwich Crag, although 

 not contemporaneous with the Amstelian strata, also may have had 

 a similar origin: the heaping-up of sand, and of dead shells against 

 the western margin of the Crag sea, being favoured by the prevalence 

 at that time of easterly winds. 2 



I have given my reasons elsewhere for believing that at a some- 

 what later period the estuary of the Chillesford Clay formed one of 

 the outlets of these rivers, 3 as did afterwards also (as pointed out by 

 Mr. Clement Reid) the estuary of the so-called Forest-bed of the 

 Cromer coast. 4 



The following diagrammatic section, drawn from Bramerton near 

 Norwich to Southwold, shows the increasing thickness and dip of 

 the Icenian Beds in a south-easterly direction, that is, towards 

 Holland. 



Fig. 6. — Section from Bramerton, near Norwich, to Southwold. 



Bramerton Beccles Southwold 



i, — 50 

 S.E.i 



[The Glacial deposits are omitted.] 



It should also be noticed that the gradually increasing dip and 

 thickness of the Icenian Beds from south to north is of the same 

 character as that of the Amstelian deposits of Holland, as shown by 

 the deep borings at Utrecht, Amsterdam, and elsewhere. 5 



VI. Summary. 



The line separating the Older and the Newer Pliocene deposits of 

 the East of England should be drawn between the Lenham Beds 

 (zone of Area diluvii) and the Coralline Crag, instead of between 

 the latter and the Crag of Walton, as hitherto. 



1 Quart. Journ. Geol. Soc. vol. Hi (1896) pp. 753, 761 & figs. 3-1. 



2 Gradual and concurrent subsidence seems to be a common feature of delta- 

 formation in all parts of the world. 



3 Quart. Journ. Geol. Soc. vol. lii (1896) p. 770. 



4 Mem. Geol. Surv. (1882) ' Cromer ' p. 57. 



5 Quart. Journ. Geol. Soc. vol. lii (1896) fig. 4, p. 761. 



