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 size. 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 equatorial drift in its eastern extension and of 
the Gulf Stream was then far more powerful in raising tke 
