U.S. Geological Survey Home AASG Logo USGS HOME CONTACT USGS SEARCH USGS
National Geologic Map Database

Geologic Unit: Lewis

Usage:

Lewis Shale (CO*,NM*,UT*,WY*)


Subunits:

(alphabetical): Dad Sandstone Member (WY*), Huerfanito Bentonite Bed (CO*,NM*), Teckla Sandstone Member (WY*) or Teckla Sand Member (WY).


Geologic age:

Late Cretaceous (Campanian to Maastrichtian)*


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

Named from occurrence at Fort Lewis, in La Plata Valley, [in sec. 3, T. 34 N., R. 11 W., Kline quadrangle, La Plata Co.], western CO (Cross and Spencer, 1899).
Principal reference section: in SW/4 SW/4 sec. 13 and SE/4 SE/4 sec. 14, T. 22 N., R. 89 W., [in vicinity of Lat. 41 deg. 52 min. 22 sec. N., Long. 107 deg. 24 min. 31 sec. W., Rawlins Peak SW 7.5-min quadrangle], Carbon Co., southern WY (Gill and others, 1970).


AAPG geologic province:

Bighorn basin*
Green River basin*
Powder River basin*
San Juan basin*
Wind River 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 ([ ]).