- Usage in publication:
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- McMillan formation
- Modifications:
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- Named
- Dominant lithology:
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- Shale
- Limestone
- AAPG geologic province:
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- Cincinnati arch
Summary:
McMillan formation proposed to encompass the Bellevue, Corryville, and Mount Auburn, here reduced to members as they are closely related and not of sufficient importance to be separately mapped. Along McMillan Street in Cincinnati, 85 ft of strata composing this formation are fairly well exposed. Overlies Fairview formation and underlies Richmond group. Age is Late Ordovician. [According to Wilmarth (1938, US geologic names lexicon, USGS Bull. 896), at the time of publication McMillan was treated as upper formation of Maysville group (reference not given).]
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
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- McMillan group
- Modifications:
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- Revised
- AAPG geologic province:
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- Cincinnati arch
Summary:
McMillan used at group rank in KY. Includes Bellevue, Corryville, and Mount Auburn formations as exposed in region around Cincinnati. In southern Blue Grass region, the Tate, Gilbert and Mount Auburn occupy the same interval.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
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- McMillan formation
- Modifications:
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- Revised
- AAPG geologic province:
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- Cincinnati arch
Summary:
Pg. 1029-1030. McMillan formation of Covington group. Uppermost formation of Covington group. Overlies Fairview formation; underlies Arnheim formation. Fairview and McMillan formations constitute standard for a medial Cincinnatian Maysville stage.
Source: US geologic names lexicon (USGS Bull. 1200, p. 2309-2310).
- Usage in publication:
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- McMillan Formation*
- Modifications:
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- Areal extent
- AAPG geologic province:
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- Cincinnati arch
Summary:
McMillan Formation not used in area of report. Replaced by Tate, Gilbert, and Stingy Creek Members of Ashlock Formation.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
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- McMillan Formation
- Modifications:
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- Areal extent
- AAPG geologic province:
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- Cincinnati arch
Summary:
Upper contact of McMillan Formation is not lithologically definable in its type area. On the basis of this and the restriction of the McMillan from south-central KY by Weir and others (1965), the unit is no longer valid in KY and the equivalent beds in the Maysville area are assigned to the Grant Lake Limestone.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
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- McMillan Formation
- Modifications:
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- Overview
- AAPG geologic province:
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- Cincinnati arch
Summary:
Stratigraphic column illustrates continued usage of the McMillan Formation in southwestern OH, where it includes Bellevue, Corryville, and Mount Auburn Members. Overlies Fairview Formation; underlies Arnheim Formation. Age is Late Ordovician (Cincinnatian).
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
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- McMillan Formationâ€
- Modifications:
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- Abandoned
- AAPG geologic province:
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- Cincinnati arch
Summary:
McMillan Formation (of Bassler, 1906) is here abandoned in southwestern OH [type area]. Its rocks are assigned to Corryville Formation, raised in rank. Lithologic homogeneity of McMillan is not up to the 1983 Code, according to author.
Source: GNU records (USGS DDS-6; Reston 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 ([ ]).