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Geologic Unit: Mayo
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Map showing publication footprint
  • Usage in publication:
    • Mayo formation*
  • Modifications:
    • Named
  • Dominant lithology:
    • Schist
  • AAPG geologic province:
    • Midcontinent region
Publication:

Redden, J.A., 1963, Geology and pegmatites of the Fourmile quadrangle, Black Hills, South Dakota, IN Pegmatites and other Precambrian rocks in the southern Black Hills: U.S. Geological Survey Professional Paper, 297-D, p. D199-D291.


Summary:

Named for town of Mayo, 1 mi east of Fourmile quad in Horney Peak quad, Custer Co, SD. No type section designated, but a generalized section measured and described along Fourmile Creek in Midcontinent region, where 14,000 ft are exposed between Crow formation (new name) at base and the overlying Paleozoic rocks. Is mostly a light- to dark-gray, medium-grained quartz-mica-feldspar schist. Also has quartz-mica schist, medium- to coarse-grained metagrit, and metaconglomerate, coarse-grained calc-silicate gneiss, and cummingtonite-quartz schist. Assigned to the Precambrian.

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


Map showing publication footprint
  • Usage in publication:
    • Mayo 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 with Early Proterozoic unit Xgw (Pl. 1) west of the Grand Junction fault, Berne and Fourmile quads, Custer Co, SD in the Midcontinent region. Geologic map.

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

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