A HISTORY OF NORFOLK 



The occurrence of shells in the Crag is very local, in many sections 

 we find no fossils ; but it is natural that only the fossiliferous localities 

 have attracted great attention.' In some places Nucula cobboldia, in 

 others Cyprina islandica, or Scrobicularia plana abound. Almost every- 

 where Tellina obliqua^ T. pratenuis, Pecten, Cardium, Mactra, Cerithium 

 tricinctum and fish-remains occur where shell-patches have been opened 

 up. The lower beds more usually contain shells because of the protec- 

 tion afforded by bands of clay, which, where prominent, are usually re- 

 garded as Chillesford Clay. Above this horizon we sometimes find layers 

 of iron-pan or ferruginous sandstone and gravel with casts of shells. 

 Ochreous nodules also occur, and these appear to be due to the contem- 

 poraneous breaking up of clay-seams, the clay pebbles thus formed having 

 acted as nuclei for the subsequent deposition of brown iron ore. Ochre 

 was formerly obtained from the Crag Series at Eaton, near Norwich. 



To the occurrence of two bands of shells at Bramerton Mr. J. E. 

 Taylor drew attention in 1865. The higher band has been recognized 

 as containing a larger percentage of northern moUusca, and its more 

 abundant species belong to somewhat deeper water, while in it there are 

 fewer land and freshwater moUusca than in the lower band. Three 

 horizons of shells occur locally at Whitlingham, while at Thorpe, the 

 highest stage, which yields casts of shells, is newer than any of the shell- 

 beds at Bramerton and Whitlingham. This highest stage at Thorpe is 

 approximately equivalent to the Weybourne Crag, which overlapping 

 other stages occurs directly on the Chalk at Weybourne. It is also met 

 with in places in the Bure valley, as at Belaugh (hence the name Bure 

 Valley Crag). All the marine shells found in this newer Crag, except 

 'Tellina balthica, and Anomia striata occur also in the lower portions of the 

 Norwich Crag, but the assemblage of species is more arctic in character. 

 On account of the presence, and indeed abundance, of the Tellina^ this 

 highest sub-division has also been termed the Tellina-balthica Crag. 



Towards the upper part of the Norwich Crag there is locally 

 developed, as at Aldeby, Surlingham, Wroxham and Coltishall, masses 

 or 'jambs ' of micaceous sandy clay, or clay interlaminated with films of 

 sand, and known as the Chillesford Clay, from the village of Chillesford, 

 near Orford, in Suffolk. This clay, which is from i to 18 feet thick, 

 has been used for brick-making at the localities above-named, and also at 

 Eaton near Norwich, where a pottery kiln existed in the time of Queen 

 Anne. The Crag yields water, especially when the Chalk is water-logged, 

 and the higher portions of the series yield water, which is locally upheld 

 by the Chillesford Clay. 



Above the horizon of the Weybourne Crag occurs the famous 

 Forest Bed Series, or Cromer Forest Bed, an accumulation which 

 immediately preceded the Glacial deposits. Evidence of increasing cold 

 is furnished in the deposits overlying this series. 



Huge bones of elephant and rhinoceros have been known since 

 early times to occur in the Forest Bed, and they gave rise to the tradition 



* See S. V. Wood, Monograph of the Crag MoUusca (Palseontograph. Soc). 



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