254 



HISTORICAL GEOLOGY 



upon the Lower Cretaceous. Thus in Europe there is not such a 

 sharp break between the Lower and Upper Cretaceous as in North 

 America. 



As in North America, so in Europe, Upper Cretaceous time 

 was marked by a great transgression of the sea. This marine 

 invasion, which started in the Lower Cretaceous, continued with 



Fig. 157 



Sketch map showing the relations of land and water in Europe during 

 early L T pper Cretaceous time. (Slightly modified after De Lap- 

 parent.) 



only slight interruptions well into the Upper Cretaceous, when 

 much of Europe, except Scandinavia and Russia, was submerged, 

 as shown by map Fig. 157. As in the Lower Cretaceous, the most 

 common rock to form in southern Europe was limestone. In 

 central-western Europe all types of ordinary sediments are repre- 

 sented, but, as already stated, in northern France and southern 

 England, the Cretaceous contains much chalk (e.g. Dover Cliffs) 

 which is made up of Foraminiferal shells and which implies clear, 



