The Cretaceous period was initiated by the subsidence of a large area to the south of the Gulf of Carpentaria, whereby a Lower Cretaceous sea spread southward, across western Queensland, western New South Wales and the north-eastern districts of South Australia.
In the Cretaceous period the waters withdrew from the N.E., but in the S.
Since the close of the Cretaceous period the Bohemian massif has remained above the sea; but the depression which lies immediately outside the Carpathian chain has at times been covered by an arm of the sea and at other times has been occupied by a chain of salt lakes, to which the salt deposits of Wieliczka and numerous brine springs owe their origin.
Pietra forte of the Cretaceous period is quarried north and south of the city, and has been used for centuries as paving stone and for the buildings.
Williamsonia occurs in the Upper Gondwana rocks of India; it is recorded also from strata ranging from the Rhaetic to the Lower Cretaceous period in England, Portugal, Sweden, Bornholm, Greenland, Italy and North America.
Two systems. At the close of the Cretaceous period great eruptions of basalt and basaltic tuff took place, especially in the Lisbon area.
Towards the end of the period, however, during the deposition of the Portlandian beds, the sea again retreated, and in the early part of the Cretaceous period was limited (in France) to the catchment basins of the Sane and Rhnein the Paris basin the contemporaneous deposits were chiefly estuarine and were confined to the northern and eastern rim.
Africa during the Cretaceous period (after the deposition of the Stormberg beds), and drilled these enormous craters through all the later formations.
During the later part of the Cretaceous period the sea gradually retreated and left the whole country dry.
Avicularia of this type occur in the common Flustra foliacea, in various species of Membranipora, and in particular in the Onychocellidae, a remarkable family common in the Cretaceous period and still existing.