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National Geologic Map Database

Geologic Unit: Ogallala

Usage:

Ogallala Formation (CO*,KS*,NE*,NM*,OK*,SD*,TX*,WY*)
Ogallala Group (NE,SD, and WY-local)
Misspelled Ogalalla in some early reports.


Subunits:

GROUP STATUS (alphabetical): Ash Hollow Formation (NE,SD), Box Butte Formation (NE), Olcott Formation (NE), Runningwater Formation (NE, and WY-local), Sand Canyon beds [informal] (NE-local), Sheep Creek Formation (NE, and WY-local), Snake Creek Formation (NE-local), Thin Elk Formation (SD), Valentine Formation (NE,SD).
FORMATION STATUS (alphabetical): Bridwell Member (TX), Calvert Ash Bed (KS-local), Couch Member (TX), Dellvale Ash Bed (KS-local), Edson local fauna (informal) (KS-local), Fort Wallace Ash Bed (KS-local), Rawlins Ash Bed (KS), Reager Ash Bed (KS), Reamsville Ash Bed (KS), Rhinoceros Hill local fauna (informal) (KS-local), Woodhouse Clay [unranked] (KS-local), Wray Channel Beds (CO).


Geologic age:

late Tertiary (Miocene to Pliocene)*


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

Named from exposures around Ogallala (correct spelling), located along South Platte River, [Ogallala quadrangle, scale 1:125,000], Keith Co., western NE (Darton, 1898).
Type section: on Feldt Ranch, in SE/4 sec. 33, T. 14 N., R. 38 W., 2 mi east and 0.5 mi north of town of Ogallala, [Ogallala 7.5-min quadrangle], Keith Co., western NE (Hesse, 1935).


AAPG geologic province:

Anadarko basin*
Central Kansas uplift*
Chadron arch*
Denver basin*
Las Animas arch*
Palo Duro basin*
Permian basin*
Powder River basin*
Salina basin*
Sierra Grande uplift*
Sioux uplift*
Wind River 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 ([ ]).