Notices of Memoirs — TJie Mundesley and Westleton Beds. 29 



III. — On the Strata between the Chtllesford Beds and the 

 Lower Boulder-clay. " The Mundesley and Westleton 

 Beds." By J. Prestwich, M.A., F.E.S., F.G.S., Professor of 

 Geology in the University of Oxford. 



(Britisli Association Reports : York Meeting.) 



WHERE a particular series of strata presents, in adjacent but 

 conterminous areas, markedly diiferent palaeontological and 

 lithological characters, it may be sometimes convenient, as in the 

 case of the " Eeading and Woolwich Series," to give them a double 

 geographical term, indicative of the localities where each type is 

 well developed, and its relation to the overlying and underlying 

 strata well shown. 



The beds between the Chillesford Clay and the Lower Boulder- 

 clay present such a series. Its exhibition on the coast of Norfolk, 

 although very limited, is accompanied by special palaeontological 

 features, that have caused it to be divided into the number of local 

 beds which have been described by Trimmer, Green, Gunn, Wood, 

 and Harmer, the author, Eeid, Blake, and others. It includes the 

 "Laminated Clays" of Gunn, the "Bure Valley Crag" of Searles 

 Wood, the " Westleton Shingle " of the author, and the " Rootlet- 

 bed " and " Norwich Series " of Blake. Without reverting at 

 present to the exact correlation of the several beds in the Norfolk 

 area, respecting which there is still some difference of opinion, the 

 author suggests that they should be included under a general term 

 founded on the localities where, on the one hand, their varied 

 palasontological characters are exhibited, and on the other, where 

 their peculiar petrological characters are well marked — characters 

 which the author proposes to show, in another paper, have a very 

 wide range, and serve to mark an important geological horizon in 

 some interesting questions of local physical geology. 



The Mundesley beds were described by the author in 1860, and 

 consist of alternating beds of clay, sands, and shingle, some contain- 

 ing freshwater and others marine mollusca, with a forest-growth and 

 mammalian remains at their base ; and again in 1871, including 

 them in his Westleton group (No. 5 in the author's sections), which 

 he showed to consist entirely of great masses of well-rounded 

 shingle, with intercalated seams containing traces only of marine 

 shells. Seeing the inconvenience of attaching the same term to the 

 two very distinct series of beds, and that it may conflict with other 

 local terms, the author now proposes to group this series under the 

 term of " The Mundesley and Westleton Beds," indicative of their 

 stratigraphical position in Norfolk, and of characters in Suffolk 

 which serve to trace them in their range westward and inland to 

 considerable distances beyond the Crag area, to which alone these 

 beds have hitherto been restricted. At the same time, it may be 

 convenient, for brevity, to use one term only in speaking of typical 

 cases. 



