LATER TERTIARY GEOLOGY OF EAST ANGLIA. 



91 



Although the structure of the Bure valley throughout is repugnant 

 to any Preglacial origin, it affords but slight evidence of interglacial 

 excavation. This is partly owing to the paucity of sections along 

 it, and partly to the difficulty of distinguishing between the Middle 

 and the Lower Glacial sands where the one rests on the other. A 

 section, however, of what we feel little doubt is the Middle Glacial 

 sand, occurs at a large excavation about half a mile N.N.W. of 

 Wroxham bridge, in the midst of the valley where the Lower 

 Glacial sands are easily distinguishable, either from their being 

 fossiliferous or from containing their characteristic seams of rolled 

 pebbles ; and we therefore give a line of section (No. XII) across 

 the Bure valley at this point. 



Fig. 12. — Section XII., across the Bure Valley. (Length 4 miles. 

 Vertical scale 17| times the horizontal.) 



e.s.w. 



N.N.E. 



N. 



Pits land H 



mile W. of 



Salhouse 



church. 



River 

 Bure. 



Great pit 

 3± furl. 



N.N.W. of 

 Wroxham 

 bridge. 



Pits 4 and 8 



furl. S.W. 



of Tinstead 



church. 



1. The Chalk-floor dipping north-eastward. 



4. Kemnants of the Chillesford beds (well exposed, with No. 5 over them 



on both sides of the river, near to, but not in, the line of section). 



5, 6, 7, and 11 as in fig. 5. 



N.B. The sands rise high up on the south side of the valley above the line of 

 junction of 5 and 6 ; and where this is the case there can be no doubt that they 

 belong to No. 7 ; but when, lower down, they rest below the level of No. 6, there 

 is a difficulty in distinguishing between them and No. 5. 





Not more than 2 furlongs from the great excavation in the 

 Middle Glacial last referred to, and between it and Wroxham 

 bridge, an extensive excavation in the Chillesford Clay, capped 

 by the Lower Glacial sand, occurs at about the same level, show- 

 ing the plunge into the valley which the Middle Glacial here 

 makes. This excavation lies two furlongs out of the line of 

 section XII. 



The next river is the Ant, which falls into the Bure. The valley 

 of this river is, in its lower part, similar to that of the Bure, as 

 shown in the last section, the Chalk being concealed beneath the 

 water-level, owing to the Postglacial depression before alluded to ; 

 and the original valley is now largely filled up with the alluvium 

 that covers the Postglacial forest-grown surface. The upper part 

 of the Ant valley, however, being cut out of higher ground formed 

 by the Contorted Drift, which has here been left by the interglacial 



