Britton Formation

The Britton Formation is a geologic formation deposited during the Middle Cenomanian to the Early Turonian ages of the Late Cretaceous in modern-day East Texas.[1] It forms the lower half of the Eagle Ford Group in the northern portion of East Texas. The formation was named by W. L. Moreman in 1932 for outcrops on Mountain Creek near the small town of Britton, south of Dallas.[2] In the Dallas area it has been subdivided into the Six Flags Limestone, Turner Park Member, and Camp Wisdom Member.[1][3] The Six Flags Limestone is a 3 ft (1 m) thick fossiliferous calcarenite made up of pieces (prisms) of Inoceramus clams.[4] The Turner Park and Camp Wisdom Members were subdivided based on the numerous volcanic ash beds (bentonites) found in the Turner Park, and the common occurrence of concretions in the Camp Wisdom. They are approximately 120 ft (37 m) (Turner Park) and 250 ft (76 m) (Camp Wisdom) thick in the Dallas area.[3] Thin sandstones known as the Templeton Member are found in Grayson County, north of Dallas, that are age equivalent to the lower part of the Turner Park Member. The Templeton Member was originally described as a part of the Woodbine,[5] but it was recently placed in the Britton Formation of the Eagle Ford Group based on its age as derived by ammonites.[1] Plesiosaur remains are among the vertebrate fossils that have been recovered from its strata.[6]

Britton Formation Stratigraphic range: Middle Cenomanian to Early Turonian 96 to 93 million years ago[1]
Type	Geological formation
Unit of	Eagle Ford Group
Underlies	Arcadia Park Shale
Overlies	Tarrant Formation
Lithology
Primary	Shale
Other	Marl, limestone, sandstone, volcanic ash beds
Location
Region	East Texas
Country	United States
Type section
Named for	Britton, Texas[2]
Named by	W. L. Moreman[2]

Paleofauna

Vertebrate fossils found in the Britton Formation include plesiosaurs and shark teeth.[6]

Invertebrate fossils found in the Britton Formation include crustaceans, ammonites, Inoceramus, foraminifera, and ostracods.[2][7]

Archosaurs of the Britton Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Cimoliopterus	C. dunni[6]				A pteranodontoid.	Cimoliopterus

References

1. Denne, R. A., Breyer, J. A., Callender, A. D., Hinote, R. E., Kariminia, M., Kosanke, T. H., Kita, Z., Lees, J. A., Rowe, H., Spaw, J. M., and Tur, N. (2016) Biostratigraphic and geochemical constraints on the stratigraphy and depositional environments of the Eagle Ford and Woodbine Groups of Texas: in Breyer, J. A. (ed.), The Eagle Ford Shale: A renaissance in U.S. oil production, AAPG Memoir 110, p. 1-86.
2. Adkins, W. S. (1932) The Mesozoic systems in Texas, in E. H. Sellards, W. S. Adkins, and F. B. Plummer, eds., University of Texas Bulletin 3232, 1007 p.
3. Reaser, D. F. (2002) Geology of the Dallas-Ft. Worth Metroplex and local geologic/meteorologic hazards: Upper Saddle River, New Jersey, Pearson Custom Publishing, 193 p.
4. Norton, G. H. (1965) Surface geology of Dallas County, in The geology of Dallas County: Dallas Geological Society, Dallas, Texas, p. 40–125.
5. Bergquist, H. R. (1949) Geology of the Woodbine Formation of Cooke, Grayson, and Fannin Counties, Texas: USGS, Oil and Gas Investigation, Preliminary Map 98.
6. Timothy S. Myers (2015) First North American occurrence of the toothed pteranodontoid pterosaur Cimoliopterus. Journal of Vertebrate of Paleontology (advance online publication) DOI:10.1080/02724634.2015.1014904 http://www.tandfonline.com/doi/full/10.1080/02724634.2015.1014904
7. Stenzel, H. B. (1952) Decapod crustaceans from the Woodbine Formation of Texas: USGS Professional Paper 242, p. 212-217.

See also

• Plesiosaur stratigraphic distribution