500 THE TERTIARY PERIOD 



there again. Probably the upheavals at the end of the Bridger 

 and at the end of the Eocene had made the climate much drier, 

 by cutting off the moisture-laden winds. 



Foreign. — The Old World Eocene has a very different devel- 

 opment from that of North America, the eastern continents not 

 assuming their present outlines till much later. At the close of 

 the Cretaceous period extensive geographical changes had taken 

 place in Europe, consisting chiefly in the retreat of the sea from 

 wide areas which it had occupied in the Cretaceous. This was 

 especially the case in Russia, northern Germany and France, and 

 southern England, and in place of the great gulf which had occu- 

 pied these regions (see p. 484) were found only scattered bodies 

 of fresh and brackish water. At a later time the sea again 

 advanced over part of these areas, which explains the general un- 

 conformity between the Cretaceous and Tertiary strata. In south- 

 ern Europe the Mediterranean regained the great expansion which 

 it had partly lost in the latter part of the Cretaceous, extending 

 far over northern Africa, where there is a gradual transition be- 

 tween the Cretaceous and Eocene, and transgressing over southern 

 Europe. A long, narrow arm of this sea extended from southern 

 France, past the north side of the future Alps and Carpathians, 

 into western Asia. Another narrow sea, or strait, extended down 

 the east side of the Ural Mountains, from the Arctic Ocean to the 

 expanded Mediterranean, completely cutting off Europe from Asia. 

 From Asia Minor the Mediterranean extended across Persia and 

 Turkistan, northern India, Borneo, and Java, to the Pacific, sepa- 

 rating the southern peninsulas from the Asiatic mainland. There 

 was thus a continuous sea around the earth, everywhere separating 

 the southern continents from the northern. 



In the Alpine and north African regions were accumulated thick 

 masses of limestone, largely composed of the gigantic foraminiferal 

 shells called NummuUtes, but in northern Europe no such widely 

 spread formations occur. After the Eocene had continued for 

 some time, a marine basin, the Anglo-Gallic, was formed over 

 southern England, northern France, and Belgium, which contains 

 a succession of alternating marine, brackish, and fresh-water strata. 



