104 LAND MAMMALS IN THE WESTERN HEMISPHERE 



2. Eocene Epoch 



North America. — The Eocene witnessed quite extensive 

 geographical changes, though but little is known of it in Central 

 or South America, or the West Indies. Along the Atlantic 

 and Gulf coasts of the United States there was an extensive 

 submergence of the coastal plain, the sea covering the southern 

 half of New Jersey and extending thence to the southwestward 

 in an ever broadening band, through the South Atlantic and 

 Gulf states. Northern Florida was under water and the Gulf 

 extended as a narrow sound, known as the "Mississippi Em- 

 bayment, " up the valley of that river to southern Illinois and 

 westward into Texas. The Embayment was present in th^ 

 Cretaceous and again in the Eocene, but it is not known 

 whether it persisted through the Paleocene ; probably it did 

 not, as the whole Atlantic coast region appears to have stood 

 at a higher level then than now. While the condition of 

 Mexico and Central America during the Eocene is not known 

 in any save the vaguest manner, it is evident that there was 

 then a broad communication between the Atlantic and the 

 Pacific, completely severing North and South America, though 

 the place of this transverse sea has not been fixed. On the 

 Pacific side, a long, narrow arm of the sea occupied what is now 

 the great valley of California, extending north into Oregon and 

 Washington. It will be noted that in North America the 

 Eocene sea was almost confined to the neighbourhood of the 

 present coast-lines, nowhere penetrating very far inland, except 

 in the Mississippi Embayment, and thus differing widely from 

 the condition of Europe at that epoch, where much of what is 

 now land was submerged. The greatly expanded Mediter- 

 ranean covered most of southern Europe, where the great 

 mountain ranges, the Pyrenees, Alps, etc., had not yet been 

 formed. Very important, from the point of view of American 

 geography, is the fact that Europe was completely separated 

 from Asia by a narrow strait or sea, which ran down the eastern 



