- Usage in publication:
-
- Bald Mountain lake beds member*
- Modifications:
-
- Named
- Dominant lithology:
-
- Conglomerate
- Sandstone
- Shale
- AAPG geologic province:
-
- Great Basin province
Summary:
Named as uppermost named member (of four) of Esmeralda formation in Manhattan district, southern Toquima Range, 35 mi north of Tonopah, Nye Co, NV. Occurs in upper part of Bald Mountain to an altitude within 400 ft of top. Composed of series of conglomerate, tuffaceous sandstone, and shale. Also includes two units of rhyolitic tuff. Overlies Diamond King member (new) (Esmeralda formation). Underlies quartz latite member [informal] (700 ft thick in upper part of Esmeralda formation). Shown on map of Manhattan district as probably late Miocene(?) age.
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Bald Mountain Formation*
- Modifications:
-
- Revised
- Age modified
- Geochronologic dating
- AAPG geologic province:
-
- Great Basin province
Summary:
Bald Mountain Lake Beds Member (Esmeralda Formation) of Ferguson (1924) is raised to formational status and called Bald Mountain Formation due to miscorrelation with type Esmeralda. Contact with overlying tuff of Peavine Creek identical to that defined by Ferguson (1924) between his Bald Mountain Lake Beds Member and quartz latite member [= tuff of Peavine Creek of Shawe]; contact with underlying Diamond King Formation similar to Ferguson's (1924) Diamond King Member with addition of some local coarse-grained sedimentary beds. Lithic content similar to Ferguson (1924) unit with addition of abundant coarse-grained fluvial layers (as coarse as cobble conglomerate) in areas beyond what Ferguson mapped. Age is latest Oligocene based on K-Ar (biotite) and fission-track (zircon) ages of 25 Ma on underlying Round Rock Formation and 24.6 Ma on overlying tuff of Peavine Creek. Age of Bald Mountain Lake Beds Member was considered late Miocene based on correlation with type Esmeralda.
Source: GNU records (USGS DDS-6; Menlo 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 ([ ]).