CENOZOIC TIME — TERTlAEY. 



881 



a large bay on the Arctic shores, and an extended " Gulf of Mexico " at its 

 southern limit. Isolated salt lakes probably remained for a while over the 

 Interior, of which Great Salt Lake of Utah is the last survivor; but no 

 marine Tertiary strata found in and about them are known to exist. 



The submerged portions of the continent, or the areas of marine rock 

 making, were therefore confined to the borders of the continent, — the 

 Atlantic border, the Gulf border, and the Pacific border. This general 

 condition of the continent during the early Tertiary is represented on the 

 accompanying map, Fig. 1468. 



1468. 



Map of North America showing the parts under water in the Tertiary Era ; the vertically-lined is the Eocene ; 

 the horizontally-lined, the Miocene or Miocene and Pliocene ; the cross-lined, the Eocene and later Tertiary. 



It is observed on the map that the condition of the Atlantic border was 

 much like that of the Cretaceous period ; that Florida was under water, as 

 then, and that the Mississippi bay was scarcely diminished in extent during 

 the time of greatest submergence. 



The portions of the Tertiary area which are lined vertically are those 

 of the Eocene beds, and those lined horizontally, of the Miocene or Mio- 

 cene and Pliocene. The map thus indicates the fact that along the Atlantic 

 coast region the sea had nearly the same limit through both the Eocene and 

 Miocene periods ; but that on the Gulf border a great retreat of the waters 

 took place before the beginning of the Miocene. 



On the Atlantic border northeast of New Jersey, Tertiary beds have been 

 identified by fossils only on Martha's Vineyard ; and, doubtfully, through 

 shells brought up by the dredge, on St. George's Shoal, east of Cape Cod, 

 Dana's manual — 56 



