STRATIGRAPHIC SUMMARY. 659 



Lower Oligogenic or Vigksburgian. 

 Ocala limestone. 

 Vicksburg limestone. 



The Vicksburg limestone is also known as the Orbitoides lime- 

 stone, from the abundance of Orbitoides mantelli; the Ocala lime- 

 stone is also called the Nummulitic limestone from the abundance 

 of Nummulites willcoxi Heilprin. 



In central Florida the Chipolan or Middle Oligocenic includes 

 in descending order — Tampa limestone, Orthaulax beds and Haw- 

 thorne beds. In Georgia, the Vicksburg limestone is succeeded by 

 the Altamaha grits which form basal Mid-Oligocenic and this by 

 the Bainbridge residual beds, representing the remainder of the 

 Oligocenic. In Alabama, Mississippi, Louisiana and Texas, the 

 Grand Gulf beds represent the Middle Oligocenic or Chipolan. In 

 the last two of the states mentioned, the Frio clays overlying, also 

 belong to the Middle Oligocenic. 



Typical Oligocenic beds are mostly wanting on the Atlantic coast 

 of the United States though the Cooper River marls of South 

 Carolina are placed here. The Shiloh marls of New Jersey also 

 have some Oligocenic elements. In the West Indies, however, 

 Oligocenic deposits are well developed. Here belong the Bowden 

 beds of Jamaica, the Hayti marls of Hayti, the Monkey Hill beds 

 of the Isthmus of Darien, the Coroni beds of Trinidad and the 

 Bonilla beds of Costa Rica. These are all referred to the Chipolan. 

 The Naparima or San Fernando series of Trinidad and the Gual- 

 lava sandstone of Costa Rica, are referred to the Vicksburgian. 



On the Pacific coast, the San Lorenzo beds of California, the 

 upper part of the Puget group of Washington and the Astoria 

 shales of western Oregon, represent the Oligocenic. The Sespe 

 beds of southern California are more doubtfully referred to the 

 Oligocenic. 



The continental deposits of Oligocenic age are represented by the 

 John Day beds of eastern Oregon, the White River beds of South 

 Dakota, Nebraska, etc. {Brule and Chadron formations), and the 

 Florissant " lake beds "of Florissant, Colorado, celebrated for their 

 rich insect fauna. 



