488 



PLIOCENE MOLLUSCA. 



and until now I have never heard it suggested that they may be Miocene. If the 

 stratigraphical evidence is of any value and the Diestien beds are of Pliocene age, 

 the Lenham bed must be Pliocene also, though belonging, I consider, to its Lower 

 and not to its Upper division. 



The zoological evidence, so far as it goes, points in the same direction. The 

 Lenham-Diestien beds, it is true, contain some characteristic Miocene or Lower 

 Pliocene fossils unknown from either the Coralline or the Casterlien zones, but 

 they include also a considerable proportion of a more recent character which 

 would seem out of place in a typical Miocene deposit. 



For zoological, therefore, as well as for stratigraphical reasons, I draw what 

 seems to me a well-marked line separating the Lower and Upper Pliocene, between 

 Lenham and the Coralline Crag. The line l)etween the Coralline Crag and the 

 Waltonian, as explained above, appears to me much less distinct. 



The term " Red Crag," including, as it does, beds differing considerably in age 

 and character, is vague and, when we attempt to correlate them with those of 

 other countries, inconvenient, the Scaldisien of Belgium with its southern fauna 

 representing one part of it and the Amstelien of Holland, which contains northern 

 species, another. Retaining it, therefore, for general use it seems desirable to 

 adopt for its different horizons some more definite and distinctive names. 



At a meeting of the British Association for the Advancement of Science at 

 Dover in 1899^ I proposed the following classification of the Pliocene deposits of 

 the East of England (republished with a slight alteration in Vol. I, p. 5 of the 

 present work) with that of their Belgian and Dutch equivalents : 



Upper Pliocene. 



Iceuiau . 



Butleyan . 



Newl)ouruiau 

 Waltonian 



C j Weybourue horizon (zone of Tellina halthica) 

 Chillcsford horizon (estuariue) 

 Norwich iiorizou (zone of Astarte borealis) 

 Zone of Cardium (jroe)ilandicuni 



Boytonian 

 Gedgravian 





Oakley horizon ) p at j i • 



^TT M. v. ■ {■ zone of JSiepTunea contraria 

 Walton horizon ) -'- 



(Containing Nassa reticosa and some other 

 characteristic Red Crag species) 



h Amstelien. 



jPoederlien. 

 [Scaldisien. 



Casterlien, zone of Isocanlia 

 cor. 



Lower Pliocene. 



Lenham bed 



Zone of Area diluvii 



\ Diestien, zone of Terebratula 

 \ grandis. 



1 Trans, of Sections, p. 75L 



