GEOLEX database
Geologic Unit: Alder
Usage:
Alder Group (AZ*)
Alder Formation (AZ*)
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Type Locality:
Named from typical exposures in vicinity of Alder Creek, in central segment of Mazatzal Range, Jerome area, AZ. Crops out extensively in Mazatzal Mountains, eastern Tonto basin, Black Hills, and to small extent in Del Rio area (Wilson, 1937 [abs.], 1939). [From US geologic names lexicon, USGS Bull. 1200]
Subunits:
GROUP STATUS (alphabetical) --all in AZ: Board Cabin Formation, City Creek Formation, Flying W Formation, Houden Formation, McDowell Mountains Formation, Rackensack Canyon Formation, Reef Ridge Formation.
Unit Name History:
Named Alder sedimentary series of Yavapai group (Wilson, 1937 [abs.], 1939).
Revised to Alder Formation, divided into 3 unnamed members (Gastil, 1954 [abs.], 1958).
Revised to Alder Group, divided into 6 formations; Areal limits; Revised; Adopted by the USGS (Anderson and Creasey, 1958).
Not used in Prescott-Jerome area, replaced with Big Bug Group (new) (Anderson and others, 1971).
[When referring to the Alder sedimentary series of Wilson (1937), please use informally. The practice of employing "Series" for lithostratigraphic or lithodemic nomenclature is now regarded as improper (see ACSN, 1961, 1970; NACSN, 1983). The term "Series" is applied formally only to chronostratigraphic units.]
Note: If you need more information, please contact Nancy Stamm (nstamm@usgs.gov).
Asterisks (*) indicate usage by the U.S. Geological Survey. Other usages by state geological surveys.
"No current usage" implies that a name has been abandoned or that it has fallen into disuse. Former usage and, if known, replacement name given in parentheses ().
Slashes (/) indicate unit name usage violates the 1983 North American Stratigraphic Code. This violation may be explained within brackets ([ ]).
U.S. Department of the Interior, U.S. Geological Survey, Reston, VA, USA
URL http://ngmdb.usgs.gov/ngmdb/ngm_catalog.ora.html
Database project personnel
Last modified: 7-Jan-2007