NEOZOIC GEOLOGY IN EUROPE. 485 



vears it was universally considered to have been formed in 

 deep water, like the Globigerina ooze of the Atlantic floor ; 

 but this view received a severe shock when Gwyn Jeffreys 

 stated that, from a consideration of the molluscan fauna, he 

 would infer that it had been laid down in shallow water. 1 

 Since that time opinion has been much divided, and the 

 evidence of the fauna has frequently been discussed. The 

 subject has recently been approached from a different 

 point of view by Hume (20), " 2 who has devoted much atten- 

 tion to the chemical and microscopical examination of the 

 rock. He shows that the amount of terrioenous material 

 in the Cretaceous beds gradually decreases from the Upper 

 Greensand to the Upper Chalk, and from this he infers a 

 gradual sinking of the land and of the floor of the sea. 



Even from the general character of the Cretaceous de- 

 posits alone, we may conclude that, in the Anglo- Parisian 

 basin, land lay towards the north in Northern Scotland, 

 and towards the west in Ireland, the West of England and 

 Brittany, for the deposits towards those areas are sandy ; 

 and, moreover, the upper beds overlap the lower towards 

 the west. A relatively open sea lay over Kent and the 

 East of England. More detailed examination shows that 

 the same general distribution of land and sea existed 

 throughout the Upper Cretaceous period. 



Beginning with the Upper Greensand, which is largely 

 of terrigenous origin, Hume points out that it is over 

 100 feet thick in Dorset, and that it thins towards the 

 north and east, and dies out altogether at Dover and 

 Rochester, showing that the land from which the materials 

 were derived lay towards the west. From the abundance 

 of glauconite grains, as well as the character of the fauna, he 

 supposes that this deposit was formed at an approximate 

 depth of 150 fathoms. It was, no doubt, more distinctly 

 littoral towards the west. 



In the case of the Lower Chalk, on the other hand, in 

 which the calcareous material is in excess of that derived 



1 Brit. Ass. Rep. (1877). Trans, of Sect, pp. 79-87. 



2 See also Hume, Chemical and Micro-Mineralogical Researches on 

 Upper Cretaceous Zones in the South of England, London, 1893. 



