NORWICH CRAG SERIES. 469 



Blake's pit, Bramerton, Scrohiadaria plana is abundant, while it is exceedingly 

 rare in the adjoining pit on the Common. Calyptma Chinensis and Loripes 

 divaricatus are abundant in a lane-cutting close by, in Kirby Bedon parish, and 

 not nearly so common in either of the pits at Bramerton. At Arminghall Rlactra 

 ovalis is so abundant that Mr. J. E. Taylor well observed that the deposit might 

 be called the Mactra-h?:A. In one pit at Wroxham Astarte borenlis is particularly 

 common, Tellina Baltliica is very rare ; while at Belaugh the reverse is the case. 

 The fact is, that not only sands, gravels, and clays, but also shell-beds were 

 forming at one and the same time in different areas throughout the history of the 

 Norwich Crag ; and that there was an uninterrupted succession of life and shell- 

 deposits, however locally they may be preserved. Hence it is not possible to 

 correlate local and minor subdivisions in different places. 



Bure Valley Beds. — These Beds, so named by Mr. Wood in 

 1866, comprise most of the pebbly sands and gravels that overlie 

 the Chalk and underlie the Lower Glacial Brickearth (Contorted 

 Drift, etc.), in the valley of the river Bure, in Norfolk. They are 

 characterized by Tellina Balthka {solidula), and, chiefly on account 

 of the presence of this shell, the Bure Valley Beds were separated 

 from the Norwich Crag by Messrs. Wood and Harmer, and grouped 

 by them as Lower Glacial.^ The typical Bure Valley Beds were 

 described by them at Belaugh, Wroxham, Crostwick, etc. ; and 

 only at Horstead, Coltishall, and Burgh- next- Aylsham were 

 fossiliferous sections of any lower portion of the Norwich Crag 

 Series (Chillesford Beds) recognized, by these authorities, in the 

 Bure Valley. There is, however, rarely any satisfactory sepa- 

 rating line between the so-called Bure Valley Beds and the 

 Norwich Crag, and they are best united under the more compre- 

 hensive name of the Norwich Crag Series. 



The term Mundesley and Westleton Beds has been applied by Prof. Prestwich 

 to beds of the age of the Bure Valley Beds, but the Mundesley Beds occur on top 

 of the Cromer F'orest Bed Series, and the Westleton Beds (of Westleton) belong 

 to the Glacial Series.* (See sequel.) 



When Messrs. Wood and Harmer separated the pebbly gravels in which Tdllifia 

 Balthka occurs from the Norwich Crag, it was believed that this shell was con- 

 fined to Glacial and Recent deposits. In 1876, however, Mr. John Gunn and 

 Mr. A. C. Savin obtained many specimens in the estuarine part of the Cromer 

 Forest Bed Series, and Mr. Clement Reid subsequently traced the Weybourn 

 Crag (also grouped as Lower Glacial by Messrs. Wood and Harmer) beneath that 

 series.^ Tellina Balthka may thus be said to characterize the upper zone of the 

 Norwich Crag Series, and its introduction may have followed the gradual encroach- 

 ment of the Crag sea further and further northward, and be due to submergence 

 which opened up connexion with a previously distinct marine area. 



The Bure Valley Beds contain Astarte borealis, A. compressay 

 Cardium edule, ]Mya arenaria, Tellina obliqua, Littorina littorea, 

 Purpura lapillus, etc. ; and with the exception of Tellina Balthica, 

 all the marine MoUusca found in it occur in the lower stages of the 

 Norwich Crag. 



Weybourn Crag. — At Weybourn the Crag beds (Weybourn Sands 



1 Q. J. xxii. 547 ; G. Mag. 1869, p 232, 1870, p. 20. 



2 G. Mag. 1882, p. 452; Prestwich, Q. J. xxvh. 461, G. Mag. 1881, p. 466, 

 1882, p. 29. 



3 Proc. Norwich Geol. Soc. i. 50 ; J. H. Blake, Ibid. 141 ; C. Reid, G. Mag. 

 1877, p. 301. 



