Usage:
/Black Knob quartzite [informal, unranked] in Pacheta Member of Lowell Formation of Bisbee Group (AZ-recognized locally in Bisbee area)
[Use of identical geographic names to several minor units in one vertical sequence (Black Knob quartzite and underlying Black Knob dolomite) is considered informal nomenclature (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021).]
Geologic age:
Early Cretaceous (Aptian)
Type section, locality, area and/or origin of name:
[Occurs in southern Mule Mountains (Black Knob Ridge section), north of International Monument No. 89, in N/2 sec. 14, T. 24 S., R. 25 E., Bisbee 15-min quadrangle, Cochise Co., southeastern AZ. Also occurs in the Ninety One Hills area, local name for hills in secs. 14 and 23, T. 24 S., R. 24 E., immediately north of International border in vicinity of International Monument No. 91, southeast of Bisbee Junction on Southern Pacific RR, Bisbee 15-min quadrangle, Cochise Co., southeastern AZ; area includes type locality and standard section of Lowell Formation (see Stoyanow, 1949).]
AAPG geologic province:
Pedregosa 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 conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).