TIIK CKKTACEOU8 SY8TKM -",L';} 



Cretaceous age in Hanover, Posen, and the Moscow area, it seems 

 1'ioKiMc ih.it Prussia and Poland were land surfaces at this time 

 Fig. 175) and were not submerged till Aptian or Albian times. 

 We knmv that it was in Aptian time that the subsidence carried 

 the sea across the English isthmus, an-1 it may well have been at 

 i la- same epoch that a strait was formed across Prussia and that 

 l-Vnno-Scandia was reduced to the condition of a large island. 



In Albian and Cenomanian times there was a more rapid 

 Mihsidence, and the continental land was broken up into a number 

 of islands. The Southern and Northern oceans were united across 

 France and England, much of the Sarmatian land was submerged, 

 and the central area was reduced to an island which, at any rate 

 in Cenomanian time, extended only from the Ardennes to Bohemia. 

 Minor changes subsequently took place, with a temporary 

 i-lfvation of the Franco-British area, during the time of the Holaster 

 planus chalk, but the renewed subsidence of Senonian time must 

 have still farther reduced the land-areas till the only remaining 

 large tract of land in the European region was that of Fenno- 

 Scandia, for of this only a small portion was ever submerged. 



This subsidence appears to have reached its maximum during 

 the Campanian epoch, for the zones of Actinocamax quadratus and 

 Belemnitella mucronata seem to have had the widest extension 

 bdth ever Limbourg and over Scania. At this time it is probable 

 that the British area was reduced to an archipelago of islands (see 

 Building of the British Isles, 1911), and it is doubtful whether any 

 part of England remained above water ; even of Wales only those 

 [arts continued as islands which are now more than 2000 feet 

 aliove the sea. 



French geologists seem to have taken it for granted that 

 Brittany and the Central Plateau of France still formed islands in 

 the Senonian and Campanian Seas ; apparently because no trace of 

 Cretaceous strata has been found upon them. But the existence of 

 land cannot be postulated on negative evidence ; the question to be 

 considered is how far the chalk of neighbouring areas is likely to 

 have been prolonged over them. In the case of Brittany we have 

 every reason to suppose that Turonian, Senonian, and higher chalks 

 followed the Cenomanian over the Cotentin and down the Channel 

 area; and as no part of Brittany rises to more than 1400 feet 

 above sea-level, while Dartmoor rises to 2000, it seems probable 

 that if the latter was entirely submerged, the former was also. 



With respect to the Central Plateau there is more to be said. 

 Since the central and southern portions of it are over 5000 feet 

 above existing sea-level, it might be thought that these must have 

 remained above that of the Cretaceous Sea ; but we must remember 



