THE 



PLIOCENE MOLLUSCA 



OF 



GPtEAT BRITAIN. 

 VOLUME II. 



INTRODUCTION. 



The commencement of a new volume gives me the opportunity of offering 

 a rapid summary of my views as to the relation of the various horizons of the 

 English Crag to each other and to those of Belgium and Holland, as well as to 

 the different conditions under which they may have originated. 



It seems desirable, however, in the first place to discuss with some care an 

 opinion lately expressed by my friend Mr. R. B. Newton, that " the Coralline 

 Crag, the St. Erth beds and the Lenhara beds of Britain, together with the 

 Diestien and Anversien of Belgium, are of Upper Miocene or Mio-Pliocene age, 

 while the Boxstones or Nodule beds of East Anglia should be referred to the 

 Vindobonean division of the Middle Miocene."^ A recent paper by Mr. A. Bell^ 

 supports the view that the Boxstone fauna is considerably older than the 

 Coralline Crag, but I cannot think the latter has any close relation to the Lenham 

 bed and still less to the Anversien (Miocene) of Belgium, zones a Panopaea 

 Menardi and a PecUmcidus pilosus. Belgian geologists consider that the latter 

 deposits indicate approximately the western limit of the Anversien sea. No traces 

 of these beds are known in the region between Antwerp and the Belgian coast. 

 That the Miocene sea ever reached the Coralline Crag region of Suffolk seems to 

 me improbable. 



For some time I have considered, on the contrary, that the fauna of the 

 Coralline Crag resembles more nearly that of the Waltonian of Essex and of its 

 equivalent, the Scaldisien of Belgium, and that it should be grouped, not even 

 with the Lenham-Diestien deposits as Lower, but with the former, the Waltonian 

 and Scaldisien, as Upper Pliocene. 



' Jouru. of Conch., vol. xv, p. 118, 1916. 

 2 Geol. Mag. [6], vol. v, p. 15, 1918. 



H 



