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National Geologic Map Database

Geologic Unit: Greenhorn

Usage:

Greenhorn Limestone of Colorado Group (CO*,IA,KS*,MT*,NE*,NM*,ND*,OK*,SD*,WY*)
Greenhorn Limestone of Benton Group (CO*,SD)
Greenhorn Formation (CO*,NM*,OK*)
Greenhorn Formation of Colorado Group (MN*,MT*,ND*,SD*,WY*)
Greenhorn Formation of Benton Group (SD)
Greenhorn Shale of Colorado Group (MT*)
Greenhorn Limestone Member of Benton Shale (CO*,NM,SD,WY*)
Greenhorn Limestone Member of Colorado Shale (MT*)
Greenhorn Limestone Member of Mancos Shale (NM*)
Greenhorn Calcareous Member of Cody Shale (MT*)
Greenhorn Bentonite Bed of Colorado Formation (MT)


Subunits:

FORMATION STATUS (alphabetical): Bridge Creek Member (CO*,KS*) or Bridge Creek Limestone Member (CO*,NM*,OK*,WY*), Hartland Member (NM*) or Hartland Shale Member (CO*,KS*,WY*), Jetmore Chalk Member (KS*), Lincoln Limestone Member (CO*,KS*,NM*,OK,WY*), Mosby Sandstone Member (MT*), Orman Lake Limestone Member (SD*), Pfeifer Shale Member (CO,KS*).


Geologic age:

Late Cretaceous (Cenomanian to Turonian)*


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

Named from Greenhorn Station, 14 mi south of Pueblo, CO, and for Greenhorn Creek [Pueblo Co., Pueblo and Walsenburg quadrangles] (Gilbert, 1896). [See detailed information in G.W. Stose, 1912, USGS Geol. Atlas of the U.S., Apishapa folio, no. 186, 12p.]
Principal reference section: at Rock Canyon anticline, a few mi west of Pueblo, in SW/4 sec. 30, T. 20 S., R. 65 W., and in NW/4 NE/4 sec. 36, T. 20 S., R. 66 W., Pueblo Co., CO (Cobban and Scott, 1972).


AAPG geologic province:

Anadarko basin*
Central Kansas uplift*
Central Montana uplift*
Denver basin*
Iowa shelf*
Las Animas arch*
Powder River basin*
Salina basin*
San Juan basin*
Sierra Grande uplift*
Sioux uplift*
Sweetgrass arch*
Williston basin*


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

Asterisk (*) indicates published by U.S. Geological Survey authors.

"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 ([ ]).