66o NORTH AMERICAN INDEX FOSSILS. 



XIV. The Miocenic System. 



Marine Miocenic strata are well developed in the Atlantic coastal 

 plain of North America, the Gulf region and on the Pacific coast. 

 In the east the succession is : 



Upper Miocenic or Oakvillian, including 

 Oakville beds of Texas. 



Duplin beds of North Carolina and probably the Gayhead 

 osseous conglomerate and green sands of Martha's 

 Vineyard, Mass. 

 Middle Miocenic or Chesapeakean including the Pascagoula 

 beds of Mississippi, and the Chesapeake group of Maryland 

 and Virginia, with its subdivision in ascending order into : 

 Calvert formation, Choptank formation and St. Mary's 

 formation. 

 Lower Miocenic or Ashleyan including Ashley River marls 

 of South Carolina and probably the Shiloh marls of New 

 Jersey. 



On the Pacific coast, the succession of Miocenic l)eds is as fol- 

 lows: 



Superformation. 



Pliocenic (San Diego beds). 

 Upper Miocenic. 

 San Pablo beds. 



(Disconformity.) 

 Santa Margarita beds. 



(Disconformity or unconformity.) 



Middle Miocenic. 



Monterey formation (5,000 ft.). 

 (Disconformity.) 



Lower Miocenic. 



Vaqueros formation (3,000 ft.). 

 (Generally an unconformity.) 



SUBFORMATION. 



Oligocenic (San Lorenzo) or older. 



