- Usage in publication:
-
- Trail member
- Modifications:
-
- Named
- Dominant lithology:
-
- Sandstone
- AAPG geologic province:
-
- Green River basin
Summary:
Named as lower member of Ericson formation, apparently for its occurrence in Mountain Fuel Supply Company's Trail field [T13N, R100W, Sweetwater Co, WY] in the Vermillion basin of the Greater Green River basin. Consists of massive sandstone; base grades down and intertongues with Mancos shale. Underlies middle member ("Rusty Zone") of Ericson formation. Is considered possible that base of member contains time-stratigraphic equivalents of upper part of Rock Springs formation, which would include McCourt sandstone tongue (new), Coulson shale tongue (new), and Brooks sandstone tongue (new). Age is Late Cretaceous.
Source: GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
-
- Trail Zone
- Modifications:
-
- Redescribed
- AAPG geologic province:
-
- Green River basin
Summary:
Is unranked lower fluviatile unit in the Ericson Formation of Mesaverde Group in the Rock Springs uplift area in the Greater Green River basin, southwestern WY. Rank changed from member to zone. [No explanation given for inappropriate redescription.] Overlies Gottsche Tongue (new) of Rock Springs Formation. Underlies middle unit (Rusty Zone) of Ericson. Age is Late Cretaceous. [The misuse of the rank term "zone" as applied to this lithostratigraphic unit has proliferated in subsequent published reports by Roehler and others, usually citing Smith (1961) as the source. However, Smith actually ranked the unit as a member.]
Source: GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
-
- Trail Member*
- Modifications:
-
- Overview
- Areal extent
- AAPG geologic province:
-
- Green River basin
Summary:
Is lower member of Ericson Sandstone in Washakie basin, Sweetwater Co, WY and northwest part of Sand Wash basin, Moffat Co, CO (both basins part of Greater Green River basin). Coastal-plain fluvial deposits correlated from outcrop near Rock Springs, WY, southeast into subsurface of Washakie and Sand Wash basins on basis of electric-log correlations. Areally extended in subsurface as far as gas well (station 5, sec 33, T12N, R97W) in Moffat Co, CO. Unconformably overlies Gottsche Tongue (Smith, 1965) of Rock Springs Formation. Underlies Rusty zone (Roehler, 1965) [middle member] of Ericson Sandstone. Is shown to be correlative with delta-plain deposits in middle part of Iles Formation of Mesaverde Group. Late Cretaceous age.
Source: GNU records (USGS DDS-6; Denver GNULEX).
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 conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).