- Usage in publication:
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- Little Flat Formation*
- Modifications:
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- Named
- Dominant lithology:
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- Limestone
- Siltstone
- Sandstone
- AAPG geologic province:
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- Wasatch uplift
Summary:
Named as lower formation of Chesterfield Range Group (new) for Little Flat Canyon in Chesterfield Range. Type section measured on southwest-trending spur in NW1/4 sec 29, T7S, R40E, to base of a series of prominent cliffs approximately 100 ft below crest of Chesterfield Range, Bannock Co, ID on Wasatch uplift. Replaces use of Brazer Limestone in southeast ID. Is composed of three members that total 965 ft thick. Lower member (126 ft thick) is red, pinkish-weathering siltstone and fine-grained sandstone with two fine-grained cherty limestone beds. Middle member (551 ft thick) is red, fine-grained, calcareous quartz, sandstone and siltstone, and gray, quartzose limestone. Upper member (288+ ft thick) is sandy to fine- and medium-grained, gray limestone. Overlies Lodgepole Limestone; underlies Monroe Canyon Limestone (new) of Chesterfield Range Group (new). Has Meramec brachiopods. Assigned to Late Mississippian.
Source: GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
-
- Little Flat Formation*
- Modifications:
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- Age modified
- AAPG geologic province:
-
- Wasatch uplift
Summary:
Age of the Little Flat Formation is Early and Late Mississippian.
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Little Flat Formation*
- Modifications:
-
- Revised
- Overview
- AAPG geologic province:
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- Snake River basin
Summary:
Divided into (ascending order): Delle Phosphatic Member (new) of Osagean age, Tetro equivalent of Osagean and Meramecian age, sandstone member, and sandy limestone member of Meramecian age in Little Flat Canyon, Chesterfield Range, Bannock Co, ID in Snake River basin. Little Flat lies in the foreland basin. Delle was called phosphatic member in earlier reports. Little Flat overlies Woodhurst Member of Lodgepole Limestone and underlies Monroe Canyon Limestone. Delle-Woodhurst contact is placed at top of a hardground formed on the Woodhurst. Delle also assigned as basal member of Aspen Range, Deep Creek, and Woodman Formations and of Chainman Shale, Deseret Limestone and Brazer Dolomite at other localities. Correlation of Little Flat with other lithostratigraphic units in Great Basin province and on Wasatch uplift, UT, and in Snake River basin, ID, shown on correlation chart. Areal extent map of Little Flat and of Delle.
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 ([ ]).