Coon Creek Formation

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Coon Creek
Stratigraphic range: Early Maastrichtian PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Formation or member
Overlies	Selma Chalk
Lithology
Other	Limestone, marl, sand, clay
Location
Coordinates	34°24′N 88°54′W / 34.4°N 88.9°W / 34.4; -88.9
Approximate paleocoordinates	38°00′N 66°12′W / 38.0°N 66.2°W / 38.0; -66.2
Region	Tennessee,  Mississippi
Country	USA
Type section
Named for	Coon Creek (Mississippi)
Named by	B. Wade

The Coon Creek Formation or Coon Creek Tongue is a geologic unit and Konservat-Lagerstätte located in western Tennessee and extreme northeast Mississippi.^[1] It is a sedimentary sandy marl deposit, Late Cretaceous (Maastrichtian) in age, about 70 million years old. The formation is renowned for its pristine fossils of Late Cretaceous marine invertebrates, including gastropods, bivalves, decapod crustaceans, and ammonites, particularly at Coon Creek in McNairy County, Tennessee, which the formation is named for. It is also known for producing fosslis of marine vertebrates, such as mosasaurs and plesiosaurs. Notable fossils from this formation is the gastropod Turritella, the bivalve Pterotrigonia thoracica (the state fossil of Tennessee), as well as other fossils such as crabs.

It is alternately considered its own geologic formation (as the Coon Creek Formation) or a distinct member of the wider Ripley Formation (as the Coon Creek Member or the Coon Creek Tongue).^[1][2]