12 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



Content: Marine Triassic of western Nevada and California; marine Triassic of Zacatecas and 

 red beds in Mexico; red beds of Texas and New Mexico; Newark group, North Carolina 

 to Nova Scotia; marine Triassic of the Arctic. In the Canadian Rockies the marine Triassic 

 is mapped with the "Paleozoic, undivided" (19, 20). In Oregon, Idaho, middle western 

 United States, and part of Alaska the Triassic is combined on the map with Jurassic (9), 



PERMIAN. 



Color, hght gray. 



Symbol, 11. 



Distribution: Southwestern United States; West Virginia, Ohio, and Pennsylvania; New 

 Brunswick and Nova Scotia. Elsewhere mapped with "Carboniferous, undivided." 



Content: Permian hmestone and red beds, Kansas to Texas; Permian red beds, New Mexico; 

 Opeche and Minnekahta formations. Black Hills; Dunkard group of the northern Appa- 

 lachians; red and gray sandstones and subjacent New Glasgow conglomerate of New 

 Brunswick, Nova Scotia, and Prince Edward Island. Includes some Triassic red beds in 

 mapping. 



PENNSYLVANIAN . 



Color, dark gray. 



Symbol, 12. 



Distribution: Guatemala, central and eastern United States, New Brunswick, and Nova Scotia. 



Present, though not distinguished from Mississippian, throughout the Cordillera, the 



Arctic region, and Newfoundland. 

 Content: "Coal measures" (Pottsville to Monongahela, inclusive) of eastern North America and 



their equivalents where distinguished; Carboniferous limestone of Guatemala. Mapped 



elsewhere with "Carboniferous, undivided" (14). 



MISSISSIPPIAN. 



Color, light French blue. 



Symbol, 13. 



Distribution: Guatemala; eastern North America from Oklahoma to Nova Scotia; present but 

 included in the "Carboniferous, undivided," in the Cordillera, Arctic region, and New- 

 foundland. 



Content: "Lower Carboniferous" limestones and their equivalents where they are separated 

 on the map from coal measures of the Pennsylvanian. In Guatemala the Santa Rosa 

 formation. 



CARBONIFEROUS, UNDIVIDED. 



Color, light blue. 



Symbol, 14. 



Distribution: Western North America, Arctic region, Newfoundland, and Central America; 

 subdivided into Mississippian, Pennsylvanian, and Permian in eastern North America. 



Content: Mississippian and Pennsylvanian limestones of the Cordillera including Devonian 

 where present; Mankomen formation and Nabesna limestone of Alaska; Lisburne forma- 

 tion, Alaska; Carboniferous of the Parry Archipelago, Arctic; Carboniferous of Newfound- 

 land; doubtful Carboniferous or Devonian of Honduras. 



DEVONIAN. 



Color, dark blue. 



Symbol, 15. 



Distribution: Eastern central United States and eastern Canada; Cordillera of the United States, 

 Canada, and Alaska; northwestern Canada. 



Content: Devonian as commonly defined through the Appalachians, including Helderberg at 

 the base and higher formations to Chemung and Catskill, inclusive; in the northeast, from 

 Gaspe to New York, Helderberg is included with the Silurian in mapping; in the Appa- 

 lachian zone south of latitude 38° the Devonian color on the map includes Silurian; through- 

 out the Cordillera from Mexico to Alaska the Devonian where present is mapped with 

 "Carboniferous, undivided" (14), except that it is distinguished in the Klamath Moun- 

 tains, California. 



