54 EELATIONS TO OTHER BRITISH DEPOSITS. 



In all the more southern developments that we have been 

 considering the junction of the Lower Greensand with the gault 

 is found to be abrupt and unconformable ; here, however, at 

 Downham Market there appears to be a perfect passage and transi- 

 tion from the sands below to the overlying gault 1 . An account of 

 this section will be found ante [p. 11]. 



The thoroughly distinct nature and age of this bed from the 

 Potton and Up ware nodule beds is not recognised in the work of 

 Mr Teall (Sedgwick Prize Essay 2 ), but on the other hand all these 

 deposits seem to have been taken as of approximately the same age, 

 and all are referred to the Folkestone series. And this grouping 

 has, I believe, had an unfortunate and false influence in appearing 

 to support a Folkestone sand age for the Upware and Potton 

 nodule beds. For the Downham Market truly belongs, as I also 

 doubt not, to that age ; but I find, from the fossil evidence, that 

 this bed is totally distinct from all the other worked coprolite beds 

 of the Eastern Counties, and must be kept clearly separated off 

 from them ; and thus the evidence rebounds to shew that if the 

 Downham bed is of Folkestone age then the others are not of that 

 age, but belong to some different and older period — a conclusion 

 quite in harmony with the direct evidence from their contained 

 fossils as already worked out. See supra. 



The list of Downham fossils given by Mr Teall (p. 21) is, as he 

 tells us, a mixed lot — partly gault and partly from the underlying- 

 sands and coprolite bed. Separating these out we find : 



I. Gault Species : 



Ammonites interruptus, d'Orb. Inoceramus sulcatus, Park. 



,, splendens, Sby. ,, concentricus, Park. 



Hamites, 2 sp. Nucula pectinata, Sby. 

 Belemnites attenuatus, Sby. 



These occur, all except the Belemnites, in a pale phosphatic 

 condition, such as is frequent in the gault, and quite different from 

 the Neocomian types. 



1 Mr Teall describes (in his Sedgwick Prize Essay, page 24) a gradual transition 

 from the Ironsand to the gault at Gamlingay, Cambridgeshire. This section is now 

 not visible. 



2 Mr Teall writes me that he has always believed the position of the Nodule 

 bed varies in different localities. 





