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Geologic Unit: Grizzly
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Map showing publication footprint
  • Usage in publication:
    • Grizzly formation
  • Modifications:
    • Areal extent
  • Dominant lithology:
    • Phyllite
  • AAPG geologic province:
    • Midcontinent region
Publication:

Dodge, T.A., 1942, Amphibolites of the Lead area, northern Black Hills, South Dakota: Geological Society of America Bulletin, v. 53, no. 4, p. 561-583.


Summary:

Pg. 563. Grizzly formation. Name appears on list of Precambrian rocks of area. Phyllite, about 3,000 feet thick. Overlies Flag Rock formation (new). Age is Precambrian.

Source: US geologic names lexicon (USGS Bull. 1200, p. 1620).


Map showing publication footprint
  • Usage in publication:
    • Grizzly formation
  • Modifications:
    • Areal extent
  • AAPG geologic province:
    • Midcontinent region
Publication:

Noble, J., and Harder, J.O., 1948, Stratigraphy and metamorphism in a part of the northern Black Hills and the Homestake Mine, Lead, South Dakota: Geological Society of America Bulletin, v. 59, no. 9, p. 941-975.


Summary:

Pg. 944 (fig. 1), 962. Grizzly formation. Consists almost wholly of fine-grained gray to dark-gray sericitic phyllite with no distinctive character and almost no bedding. Thickness about 3,000 feet not allowing for possible duplication by undisclosed folding; probably thicker in vicinity of Deadwood, southwestern South Dakota. Top of
formation not observed; overlies Flag Rock formation. Age is Precambrian.

Source: US geologic names lexicon (USGS Bull. 1200, p. 1620).


Map showing publication footprint
  • Usage in publication:
    • Grizzly Formation
  • Modifications:
    • Age modified
  • AAPG geologic province:
    • Midcontinent region
Publication:

DeWitt, Ed, Redden, J.A., Wilson, A.E., and Buscher, David, 1986, Mineral resource potential and geology of the Black Hills National Forest, South Dakota and Wyoming, with a section on salable commodities by J.S. Dersch: U.S. Geological Survey Bulletin, 1580, 135 p., (incl. geologic map, scale 1:250,000)


Summary:

Mapped as part of the youngest stratified unit Xsh (Pl. 1) of Early Proterozoic age in the Lead area, Lawrence Co, SD in the Midcontinent region. Extends south under cover of Cambrian sandstones into the Roubaix area in Lawrence Co. Geologic map.

Source: GNU records (USGS DDS-6; Denver GNULEX).


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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 ([ ]).

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