LATER TERTIAEY GEOLOGY OF EAST ANGLIA. 95 



explanation in this view ; that of the Middle Glacial in the way 

 attempted to be shown in the sequel of this paper ; and that of the 

 Contorted Drift by its having been ploughed out up to that point by 

 this great mass of glacier ice. The depth of the submergence which 

 the structure of the Contorted Drift proves Northern Norfolk to have 

 undergone during the Lower Glacial period renders it very difficult 

 to suppose that the Fenland, and other low-lying country beyond it, 

 did not participate in that submergence, and become covered with 

 the Contorted Drift, unless their level has been greatly lowered since ; 

 but if we assume that the land ice reached to this part at the com- 

 mencement of the Middle Glacial, as explained in the sequel of the 

 paper, it is easy to account for the great lowering of the level of 

 these districts, as well as for the destruction of the Lower Glacial 

 deposits over them, by the degradation of their somewhat soft strata 

 which such ice must have effected. In whatever way, however, 

 the valley of the Waveney and Little Ouse may have been excavated 

 and brought to its present confluent character, it seems clear to us 

 that it must have formed a channel or strait as the land rose out of 

 the Upper Glacial sea, and that the tidal scour through it was, as 

 in the case of the other East- Anglian valleys, the principal agent in 

 its >*€-excavation. 



The valley of the "Waveney presents few exposures of the Contorted 

 Drift ; but those that do occur seem to us sufficient to prove that 

 this formation once spread in considerable thickness over the district 

 through which the valley runs. The Middle Glacial, except where 

 these remnants occur, occupies so uniformly the flank of the valley 

 west of Beccles as to lead naturally to the inference that the valley 

 was excavated out of this and the overlying Upper Glacial clay 

 only, as represented by Mr. Prestwich in his well-known sections of 

 the Hoxne bed *, and was thus of Postglacial origin. The presence 

 of these remnants of the contorted drift, however, and the general 

 structure of the valleys of East and Central Norfolk which we have 

 been reviewing, appear to us to indicate that a much wider trough 

 than that which the valley now forms was interglacially excavated 

 in the Contorted Drift, and that the Middle Glacial overlain by the 

 Upper Glacial was deposited in it. Moreover, at various points 

 along the valley exposures of clay occur low down that are clearly 

 either the bed a of Section V., or else the Upper Glacial clay of the 

 high ground (No. 8), an instance of -which exists at Lopham, close 

 to the source of the river — in either case proving interglacial exca- 

 vation to some extent. 



A bed of clay with chalk debris exactly resembling the Upper 

 Glacial and also the bed marked a in section IV. seems to underlie 

 a great thickness of Middle Glacial sand in the cutting at Oulton 

 two miles west of Lowestoft. The sloped and grassed condition of 

 the cutting obscures the position of this bed relatively to the Middle 

 Glacial sand through which the cutting is made ; and instead of this 

 bed of clay underl}'ing the sand, it may be only a plunge of the 

 Upper Glacial into it ; but if such underlie does occur, then this 

 * Phil. Trar.s. I860, part ii. p. 304. 



