366 HISTORICAL GEOLOGY. 



of these are Eocene, some Miocene, some Pliocene. The 

 Eocene deposits are in the Plateau region north and south 

 of the Uintah Mountains. The Miocene and Pliocene 

 deposits are in the Plains and the Basin regions. 



These fresh-water deposits of the West are imperfectly 

 lithified, and therefore are sculptured "by erosion into the 

 curious forms called Mauvaises Terres, as already ex- 

 plained (page 248, Fig. 152). 



Physical Geography. It is easy, from the distribu- 

 tion just given, to reconstruct the physical geography of 

 the American Continent during the Tertiary. It is sim- 

 ply a restatement in another form of what we have already 

 said. On the Atlantic border the New England shore-line 

 was farther out than now, because we have no Tertiary 

 deposits exposed along that coast. The Tertiary shore- 

 line crossed the present shore-line about New York, and 

 thence passed along the line of limit of the Tertiaries of 

 the Southern Atlantic States, the waves beating there 

 against Archaean shore-rocks. On the Gulf border the 

 north shore of the Gulf did not reach quite so far as in 

 Cretaceous times (see map on page 272), but the Gulf 

 waters covered all the flat lands about the Gulf, beating 

 here on Cretaceous rocks ; extending north, as an embay- 

 ment to the mouth of the Ohio River, and then swept 

 southward, covering a broad strip on the west. The Up- 

 per Mississippi (if it existed at all) and the Ohio emptied 

 by separate mouths into the embayment. On the Pacific 

 border the waves of the Pacific beat against the foot-hills 

 of the Sierra, the place of the Coast Range being then a 

 marginal sea-bottom. Fig. 326 shows the American con- 

 tinent in Early Tertiary. 



The interior region was occupied by enormous lakes. 

 During the Eocene, the lakes were in the Plateau region ; 

 during Miocene and Pliocene times, in the Basin on the 

 one side and the Plains on the other. 



Coal. Lignite is found again in the Tertiary, espe- 



