1 12 PROF. J. PEESTWICH ON THE EELATION OF THE 



As the upper part of this section belongs to the base of the 

 Mundesley Series or else to the Porest-Eed Series, this Crag (in the 

 absence of the Chillesford Clay, which may have been denuded, or 

 may be represented by the mass of clay pebbles) occupies the 

 position of the Pluvio-marine Crag of Norwich, while there is 

 nothing to show relation to the Porest-Bed Series. The presence 

 of the pebbles and the eroded surface show, on the contrary, a 

 decided break between this Crag and the overlying beds. For 

 these reasons, and also because all the 51 species in this list, 

 are, with two exceptions, Crag species, I would assign this bed to 

 the Norwich Crag. One exception is Tellina halthica, which has 

 been found on this north-eastern coast only in the Crag Beds of the 

 Bure Yalley ; the other Astarte crehricostaia^ which is only recorded 

 from the Upper Glacial Beds. Besides these, there are found here 

 two shells — Gardium ecJiinatum and Astarte incrassata — which are 

 Eed-Crag species. On the other hand, of the 36 species recorded by 

 Mr. H. B. Woodward from the Bure-Y alley Beds, only 23 appear in 

 the above list. 



Mr. Keid, on the assumption that this Crag is the equivalent of 

 the Bure-Yalley Crag *, considers that Messrs. Wood and Harmer 

 are wrong in placing the latter above the Forest Bed ; but if I am 

 right in referring this patch of Crag to the Norwich Crag, then the 

 shingle h (fig. 8) above the lower part of the " Forest Bed " would 

 correctly represent, as supposed by Messrs. Wood and Harmer, 

 the Bure-Yalley Beds. 



It is evident that the palaeontological difi'erences are very 

 small. The only marine Bure-Yalley shell not found in the Crag 

 at Norwich is Tellina halthica. But this shell is extremely uncer- 

 tain in its habitat, and a slight difference in the quality of the 

 water or of the bottom might account for its presence in the one 

 district and its absence in the other. Dr. Gwyn Jeffreys informed 

 me that at the present day it is abundant in Swansea Bay, although 

 it is not to be found nine miles distant in Oxwich Bay. It prefers 

 brackish waters, and " though in the main a northern shell, it is 

 likewise common in many parts of the south of Europe." It is clear 

 likewise that this Bunton Crag presents far closer analogies with 

 the more distant Crag at Norwich than with the Bure-Yalley 

 Crag in the intermediate area. 



Between Bunton and Weybourn, where the Forest Series entirely 

 thins out, or few traces of it remain, the overlying Pebbly Beds 

 come into juxtaposition with the Fluvio-marine Crag beneath that 

 Series. The slight pala?ontological and lithological diflerences are 

 then not sufficient to furnish any apparent distinction, except possibly 

 in places where the AVestleton shingle retains its more pronounced 

 characters. The true faunal value of these zones can only be cor- 

 rectly determined by selecting localities, such as the one above, where 

 they cannot possibly be in contact. 



* Mr. Eeid, however, suggests the possibih"ty that the Weybourn Crag, as a 

 •whole, is the equivalent of the Chillesford and Aldeby Beds. 



