484 THE CRETACEOUS PERIOD 



nearly all of the central region, which in part became dry land 

 and in part was covered with lakes and inland seas. One of the 

 largest of these covered much of southern England, extending far 

 into Germany, and in it was deposited a great thickness of sand 

 and clay, with some shell limestone, the Wealden. The Alpine re- 

 gion remained submerged under a clear and deep sea, and the tran- 

 sition from the Jurassic is very gradual. In the oldest Cretaceous 

 epoch {Neocomiaii) a renewed transgression submerged large 

 parts of central Europe, though the sea was far less extensive than 

 that of the Middle and Upper Jurassic. In consequence, a great 

 gulf was established over southern England, northern France, and 

 north Germany to Poland, a gulf bounded on the north by the 

 highlands of Britain, Scandinavia, and northwestern Russia, and on 

 the south by a land stretching from Ireland to Bohemia ; Belgium 

 was an island. The expanded Mediterranean covered south- 

 eastern Asia Minor and northern Africa. In the Upper Cretaceous 

 the northern gulf was greatly extended, covering many areas that 

 had been land since Palaeozoic or pre-Cambrian times. Parts 

 cf this basin became very deep, and its most characteristic de- 

 posit, especially over southern England and northern France, was 

 chalk, which the microscope shows to be made up of the shells of 

 Foraminifera and to greatly resemble the modern foraminiferal 

 oozes (see p. 215). Over the Alpine region upheavals in the 

 Upper Cretaceous had established land areas, indicated by exten- 

 sive fresh-water deposits, recurring at intervals from Spain to 

 Hungary, in the latter country containing coal. The Cretaceous 

 was closed in Europe by a gradual upheaval which excluded the 

 sea from wide areas that it had occupied. 



In Africa the only extensive Cretaceous areas are those of the 

 north, where the Atlas Mountains and much of the surface of 

 the Libyan desert are made up of these rocks. A limited trans- 

 gression of the sea also took place along the western coast and 

 another on the east coast of Cape Colony and Natal. 



Southern and eastern Asia display many areas of Cretaceous 

 rocks, as, for example, in southern India and Japan. Australia 

 also has extensive areas of this system, which are best known in 



