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MGS Loc. 74b - Chickasawhay River [Mint Spring Fm] (Oligocene of the United States)

Where: Wayne County, Mississippi (31.0° N, 88.7° W: paleocoordinates 31.3° N, 82.3° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Mint Spring Formation, Rupelian (33.9 - 28.4 Ma)

• The Mint Spring formation consists of fossiliferous sands that lie disconformably above the estuarine clays and sands of the Forest Hill Formation. This contact is characterized by shell gravels that are largely comprised of the bivalve Callista,by lithified clay clasts bored by the bivalve Jouannetia , and by shark and ray teeth. Lithified clay clasts are especially common at the base of the Mint Spring Formationalong the Chicasawhay River in Wayne county. Here clay clasts are numerous enough to have produced a cobble bottom on the Mint Spring sea floor. These clasts formed a hard substrate utilized by a variety of encrusting organisms. The sands of the Mint Spring Formation are moderately clean and often show cross-bedding. These sands indicate a near-shore shelf enviromentand have macrofauna dominated by bivalves. This marine sand facies has well-preserved fossils at the type locality at the Mint Spring Bayou, at localities 99-101 in Rankin County, and at localities 89-90 in Smith County. In Wayne County, at localities 74b, 75b, and 117b, the Mint Spring Formation is only one to two feet in thickness,is very calcareous, and slightly indurated.

• formation-level stratigraphic resolution

Environment/lithology: offshore; lithified, sandy, calcareous claystone and conglomerate

Size class: mesofossils

Preservation: original aragonite, original calcite

Collection methods: bulk, mechanical,

• bivalves only

Primary reference: D. T. Dockery. 1982. Lower Oligocene Bivalvia of the Vicksburg Group in Mississippi. Mississippi Department of Natural Resources Bureau of Geology 123:1-261 [L. Ivany/S. DeLong] more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 5820: authorized by Linda Ivany, entered by Sarah DeLong on 07.12.1999

Creative Commons license: CC BY (attribution)