10 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



CONTINENTAL OLIGOCENE. 



Color, light orange (dots) . 



Symbol, 5c. 



Distribution: Great Plains of Wj^oming, the Dakotas, and Colorado. 



Content: White River group, including Chadron and Brule formations. 



EARLIER TERTIARY (EOCENE AND OLIGOCENE), 



Color, orange (horizontal ruUng) . 



Symbol, 5. 



Distribution: Central America, West Indies, and Pacific coast to Alaska. Mapped separately on 

 the Atlantic and Gulf coasts, in Greenland, and in the Interior. 



Content: Marine Eocene and Oligocene formations of Central America and West Indies; corre- 

 sponding marine formations on the Pacific coast of California and Oregon ; and coal-bearing 

 formations of Pugct Sound (Puget group) and Alaska (Kenai formation). 



MARINE EOCENE. 



Color, orange (vertical ruhng). 



Symbol, 5b. 



Distribution: Atlantic and Gulf coasts, Mississippi embayment, Jamaica, and Greenland, where 



it is separated from Ohgoceno. Elsewhere mapped with Ohgocene as "Earlier Tertiary. " 

 Content: Marine Eocene of the Atlantic and Gulf coasts, Jamaica, and Greenland, and estuarine 



deposits of the Mississippi embayment. 



CONTINENTAL EOCENE. 



Color, orange (dots). 



Symbol, 5b-l. 



Distribution: Interior basins of the western United States and Canada. 



Content: Puerco, Fort Union, Wasatch, Green River, Bridger, and Uinta formations. 



EARLIEST TERTIARY OE LATEST CRETACEOUS. 



Color, orange-brown. 



Symbol, 5a. 



Distribution: Colombia, middle western United States, and Canada. 



Content: Shoshone group; Denver and Arapahoe and equivalents in Colorado; "Upper 

 Laramie," Lance formation, "Ceratops beds," or "Somber beds" in Wyoming, Montana, 

 and the Dakotas; and Edmonton of Alberta; also "Upper Laramie" of Canadian reports. 

 In Colombia, the Guaduas or Cerro de Oro formation. 



LATE UPPER cretaceous; LARAMIE. 



Color, yellowish green. 



Symbol, 6. 



Distribution: Rocky Mountains of the United States, southern Wyoming to New Mexico. 



Content: Late Cretaceous coal-bearing formations; Laramie of the Denver Basin; "Lower 



Laramie" of southern Wyoming; and coal-bearing equivalents in Colorado and New 



Mexico. 



UPPER CRETACEOUS. 



Color, light green. 



Symbol, 7. 



Distribution: South America and West Indies; present but not generally distinguished in 

 Mexico from Lower Cretaceous; Atlantic and Gulf coasts from Mexican boundary to New 

 England; the Interior province. New Mexico to Mackenzie; Pacific coast. Lower Cali- 

 fornia to Alaska; the Arctic coastal plain of Alaska; and the west coast of Greenland. 



