CHAPTER V. 



THE FOREIGN RELATIONS OF THE UPWARE AND 

 BRICKHILL NEOCOMIANS. 



The old sea-basin in which the Upper Neocomian rocks of the 

 South of England were deposited extended far to the south towards 

 the centre of France till it reached the granite plateau of the 

 Auvergne and Puy de Dome : and in an east and west direction it 

 was bounded by the ancient rocks of Normandy and of the axis of 

 Artois (Ardennes region) *. 



But in the earlier part of the Neocomian period (Lower Neoco- 

 mian) this sea was not quite so extensive as here indicated, barely 

 reaching as far north as the present north coast of France where, 

 at that time, the great Wealden river was laying down some of its 

 immense accumulations of freshwater sediments. In this part of 

 the series therefore it can scarcely be possible to make any de- 

 tailed correlation between the South of England freshwater beds 

 and their marine representatives in the French area. 



But our Ironsand and Phosphatic series was laid down during 

 the immediately subsequent period when this Neocomian sea had 

 attained to its greatest extent and was united with the northern 

 (Anglo-Germanic) sea, through what Mr Teall 2 calls the North- 

 Eastern channel. 



Now the deposits laid down in the deep water of the Upper 

 Neocomian sea differ considerably from those formed around the 

 margins; and in searching for the extension of our Cambridgeshire 

 and Bedfordshire Lower Greensand rocks, these being shallow- 



1 A tongue or neck of land running across the eastern counties separated this 

 old sea from the northern (Anglo-Germanic) ocean. 



2 Sedgwick Prize Essay, 1875, page 40. 



5—2 



