TERTIARY AGE. 491 



Cape Cod, and the islands off southern New England ; in New Jersey, 

 and through Maryland, Virginia, and the Carolinas, over a narrow 

 coast region, and, from South Carolina, westward along the Gulf Bor- 

 der, the inner limit of the region being about one hundred miles from 

 the Gulf in Alabama, and one hundred and fifty to two hundred in 

 Texas. Along the Mississippi River, the Gulf-border region extends 

 northward to southern Illinois. 



Marine Tertiary beds occur also on the Pacific coast, in California 

 and Oregon, forming, with the Cretaceous, the Coast Range of hills. 

 Some of the Tertiary ridges are 2,000 to 3,000 feet in height. They 

 also cover the Cretaceous, over the Rocky Mountain slopes and sum- 

 mit, but alternate, in these parts, with extensive fresh-water beds. 



Lignitic beds, referred to the Lower Eocene, are well displayed 

 either side of the Mississippi, in Mississippi, Tennessee, and Arkansas. 



The Laramie beds occur over the eastern slopes of the Rocky Moun- 

 tains, on the Upper Missouri and elsewhere; over the Rocky Mountain 

 region, in Wyoming, Utah, Colorado, etc., where the thickness is sev- 

 eral thousand feet; in California, overlying the Cretaceous, and in 

 other parts of the Pacific-border region. Lignite, or carbonized wood, 

 and beds of mineral coal occur in the formation. Part of the beds 

 outcrop near the Pacific Railroad ; and the coal obtained, often called 

 lignite, is used for the engines on the road, and for metallurgical and 

 other purposes. The coal of Mount Diablo, California, and other beds 

 of the Tejon series, appear to be of cotemporaneous formation. 



The Eocene marine beds, of the Alabama period, are extensively 

 displayed in the States of Mississippi, Alabama, and Georgia; they 

 occur also at some points in South Carolina and Virginia, though gen- 

 erally concealed on the Atlantic border by the Miocene beds. They 

 have been divided, commencing below, into the Claiborne group, 

 well displayed at Claiborne, Alabama, and the Vicksburg group, so 

 named from Vicksburg on the Mississippi. Lyell, whose observations 

 in America as well as Europe first brought out the true character and 

 relations of the Tertiary formations, makes the Claiborne beds to be 

 probably the equivalent of the Middle Eocene of Great Britain, stating 

 that several of the shells (among them, Venericar.dia planicosta Lam.) 

 are identical with those of European species of that age. 



The marine Miocene beds cover a large part of the Atlantic Border, 

 and are well exhibited and full of fossils in Virginia and New Jersey. 



Over the Rocky Mountain region and part of the Eastern slopes, 

 the Tertiary beds later than those of the Laramie group are wholly of 

 fresh-water origin ; and they lie upon the upturned Laramie beds. 

 As first shown by Hayden, the beds were formed in lakes that existed 

 over the Rocky Mountain region, soon after it first emerged, and while 

 it was yet low. 



