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National Geologic Map Database

Geologic Unit: Niobrara

Usage:

Niobrara Formation (MN*,MT*)
Niobrara Formation of Colorado Group (CO*,KS*,NE*,NM*,ND*,SD*,WY*)
Niobrara Shale of Colorado Group (MT*,ND*)
Niobrara Chalk of Colorado Group (KS*)
Niobrara Marl of Colorado Group (SD)
Niobrara Marl (SD)
Niobrara Member of Cody Shale (MT*,WY*)
Niobrara Member of Colorado Shale (MT*)
Niobrara Member of Mancos Shale (CO*,NM*)


Subunits:

(alphabetical): Fort Hays Limestone Member (CO*,KS*,NE*,NM*,SD*,WY), Smoky Hill Chalk Member (CO*,KS*,NE*,SD*) or Smoky Hill Marl Member (CO*,NM*) or Smoky Hill Member (WY) or Smoky Hill Shale Member (CO*,NE*,NM*).


Geologic age:

Late Cretaceous (Turonian to Campanian)*


Type section, locality, area and/or origin of name:

Not designated. Named from Niobrara River where forms cliffs near mouth, along Missouri River, Knox Co., NE (Meek and Hayden, 1862).


AAPG geologic province:

San Juan basin*
Salina basin*
Central Montana uplift*
Powder River basin*
Denver basin*
Sioux uplift*
Las Vegas-Raton basin*
Williston basin*
Iowa shelf*
North Park basin


For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).

Slash (/) indicates name does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).