- Usage in publication:
-
- Tsadaka formation*
- Modifications:
-
- Named
- Dominant lithology:
-
- Conglomerate
- Sandstone
- Siltstone
- AAPG geologic province:
-
- Alaska Southern region
Summary:
Occurs in Tsadaka Canyon on Moose Creek below Premier Mine and on Wishbone Hill, Matanuska coal field, southern AK. Rocks formerly uppermost conglomeratic beds mapped as part of Eska conglomerate by Martin and Katz (1912). Consists of poorly indurated coarse conglomerate characterized by boulders and cobbles of granite and diorite in matrix of granitic debris and interbedded silty sandstone, siltstone, and pebbly sandstone. Is at least 700 ft thick in Tsadaka Canyon. Unconformably overlies Wishbone formation (new). Underlies relatively thin veneer of unconsolidated material in area immediately south of Wishbone Lake. Considered to be Eocene or younger in age.
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Tsadaka Formation*
- Modifications:
-
- Age modified
- Biostratigraphic dating
- AAPG geologic province:
-
- Alaska Southern region
Summary:
Age is considered to be late Oligocene (Angoonian Stage) based on fossil flora.
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 ([ ]).