PERMANENCE OF CONTINENTS AND OCEANIC BASINS. 133 



greater part of Northern Asia was swept by a westerly current ; 

 and we may imagine a North Atlantic equatorial current de- 

 flected so as to reach the arctic region, the main branch finding 

 its way into the Pacific to form a part of the Pacific equatorial 

 current; and a second current from the equatorial Atlantic ram- 

 ifying along the eastern coast of the South American Archi- 

 pelago. 



If we omit the intervening periods and pass over to an exami- 

 nation of the map of the world at the time of the chalk, we 

 shall find our continents greatly increased in siz.e. The littoral 

 and shallow-water deposits, which have formed the devonian, 

 the carboniferous, the lias, the jura, have united many of the 

 older islands. They had perhaps given to Africa much the out- 

 line which it now has, with the exception of the broad passage 

 which was still open to the Indian current, through Arabia and 

 North Africa, to the Atlantic. The European Archipelago 

 consisted of large islands. The northern part of Asia was still 

 disconnected from China, Siam, and India by a wide strait, 

 through which flowed a current joining that in the Indian 

 Ocean, and forming a large inland sea, connecting the Caspian_, 

 Black, Aral, and Baikal Seas. The islands forming the south- 

 ern extremity of South America had become connected, but 

 there was probably little change in the outlines of the archi- 

 pelago forming the northern part of South and Central America. 



But North America itself has greatly changed. There is a 

 deep bay extending from the Gulf of Mexico far up towards 

 the sources of the Missouri, while the shores of Mexico, of the 

 greater part of Texas, Louisiana, Mississippi, Alabama, Florida, 

 Georgia, North Carolina, parts of Virginia, and New Jersey are 

 still swept by the returning Atlantic equatorial stream, much as 

 the shores of the Gulf of Mexico are nowadays. Only a small 

 part of the North Atlantic equatorial current finds its way now 

 through the Central American and South American archipel- 

 agoes into the Pacific, the greater part of it raising the tem- 

 perature of the shores of North America as high as that of the 

 Gulf of Mexico at the present day. Undoubtedly the combined 

 influence of this equatoiial drift in its eastern extension and of 

 the Gulf Stream was then far more powerful in raising the 



