Usage:
Unkar Group of Grand Canyon Supergroup (AZ*)
Subunits:
(alphabetical) --all in AZ: Bass Limestone* or Bass Formation, Cardenas Lava*, Dox Formation or Dox Sandstone*, Hakatai Shale*, Hotauta Conglomerate*, Shinumo Quartzite*.
Geologic age:
Mesoproterozoic*
Type section, locality, area and/or origin of name:
Named from Unkar Valley, Grand Canyon area, northern AZ (Walcott, 1894).
AAPG geologic province:
Southern Rocky Mountain region*
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 ([ ]).