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| Fern Glen Formation | |
|---|---|
| Name | Fern Glen Formation |
| Type | Formation |
| Period | Mississippian |
| Age | Osagean (Lower Mississippian) |
| Primary lithology | Limestone |
| Otherlithology | Dolomite, chert |
| Namedfor | Fern Glen |
| Region | Missouri, USA |
| Country | United States |
| Unitof | Chouteau Group |
| Underlies | Burlington Limestone |
| Overlies | Reynoldsburg Formation |
Fern Glen Formation The Fern Glen Formation is a Lower Mississippian carbonate unit known for fossiliferous limestone, dolomite, and chert in the Midcontinent United States. It has been studied in regional stratigraphy, paleontology, and economic geology from the Ozarks to the Illinois Basin, and is an important reference in studies by workers from institutions such as United States Geological Survey, University of Missouri, Kansas Geological Survey, Illinois State Geological Survey, and American Association of Petroleum Geologists. The unit provides key biostratigraphic ties to global Mississippian frameworks such as the Osagean and Tournaisian correlations used by stratigraphers at International Commission on Stratigraphy.
The Fern Glen Formation consists predominantly of fossiliferous crinoidal and micritic limestone, with interbeds of cherty limestone and local dolomitization recognized by researchers from Missouri Geological Survey and petrographers affiliated with Smithsonian Institution. Lithologic descriptions emphasize skeletal grainstones, packstones, and nodular chert horizons correlated with regional sea-level fluctuations studied in publications tied to Geological Society of America meetings. Petrographic thin-section studies cite calcitic and microsparitic matrices, silicified bioclasts, and stylolitic surfaces comparable to sections logged by geologists from Ohio State University and Iowa Geological Survey.
Regionally assigned to the Osagean (early Mississippian), the Fern Glen Formation lies within the Chouteau Group and is stratigraphically positioned beneath the Burlington Limestone and above the Reynoldsburg and other Kinderhookian strata, as documented by stratigraphers at Indiana Geological and Water Survey and Kentucky Geological Survey. Biostratigraphic control derives from conodont, brachiopod, and crinoid assemblages tied to global Mississippian stages used by the International Commission on Stratigraphy and correlated with sections in the Appalachian Basin and Midcontinent Rift System. Sequence stratigraphy work links the unit to transgressive–regressive cycles recognized in syntheses from American Geophysical Union publications.
The formation is renowned for abundant crinoids, brachiopods, bryozoans, corals, echinoderms, and conodont elements, with taxonomic treatments published by paleontologists affiliated with Field Museum of Natural History, Yale Peabody Museum, Carnegie Museum of Natural History, and University of Chicago. Notable fossil genera recovered include diverse crinoid faunas comparable to those described from the Hamilton Group and brachiopod assemblages paralleling collections from the Hamilton Group and Chesterian Series localities. Microfossil work on conodonts and foraminifera has provided biostratigraphic markers used by researchers at British Geological Survey and National Museum of Natural History (France), while taphonomic analyses align with models developed by investigators at University of Kansas.
The Fern Glen Formation is exposed widely across the Ozark Plateaus, particularly in southern Missouri, with correlative intervals recognized in eastern Kansas, western Illinois, and northwest Arkansas; mapping and type section descriptions appear in reports from the Missouri Bureau of Geology and Mines and regional atlases produced by the United States Geological Survey. The type locality near Fern Glen, Missouri, was described by early stratigraphers associated with United States Geological Survey field parties and subsequent regional mapping by geologists from Missouri University of Science and Technology and Saint Louis University.
Interpretations indicate deposition in shallow, warm, carbonate-platform settings influenced by episodic siliciclastic input and stormites, comparable to depositional models developed for the Lower Mississippian shelf sequences of the North American Midcontinent. Paleoecological reconstructions, informed by community analyses from paleontologists at University of Oklahoma and Texas A&M University, suggest benthic-dominated assemblages with reefal to shoal facies and high crinoid abundance similar to contemporaneous faunas in the Cahaba Group and Redwall Limestone. Diagenetic features such as early dolomitization and silicification mirror processes documented in studies coordinated with Society for Sedimentary Geology.
The Fern Glen Formation provides locally important limestone resources for crushed stone, agricultural lime, and construction use, with extraction and quarry data reported by state agencies like the Missouri Department of Natural Resources and businesses cataloged by the United States Geological Survey minerals program. Its cherty horizons can affect aggregate quality and reservoir properties relevant to hydrogeology and petroleum exploration assessed by consultants and researchers from Bureau of Economic Geology and industry groups such as the Society of Petroleum Engineers. Paleoenvironmental and stratigraphic data from the unit also contribute to regional mineral-resource and groundwater studies undertaken by the National Ground Water Association and academic centers.
Category:Geologic formations of Missouri Category:Mississippian Series