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National Geologic Map Database

NGMDB

Geologic Unit: Hornbrook

Usage:

Hornbrook Formation (CA*,OR*)


Subunits:

(alphabetical): Blue Gulch Mudstone Member (CA*,OR*), Ditch Creek Siltstone Member (CA*,OR*), Klamath River Conglomerate Member (CA*,OR*), Osburger Gulch Sandstone Member (CA*,OR*), Rocky Gulch Sandstone Member (CA*,OR*).


Geologic age:

Cretaceous (Albian to Maastrichtian)*


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

Type section (composite): NE/4 SE/4 sec. 32 to SE/4 SE/4 sec. 29, T. 47 N., R. 6 W., NW/4 NW/4 sec. 29 to middle SW/4 sec. 20, T. 47 N., R. 6 W., SW/4 sec. 20 to SE/4 SW/4 sec. 17, T. 47 N., R. 6 W., Hornbrook 15-min quadrangle, Siskiyou Co., CA (Peck and others, 1956).


AAPG geologic province:

Klamath Mountains province*


NGMDB

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 ([ ]).

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Page Last Modified: Tue Jun 3 16:45:23 2014