Cason Shale

The Cason Shale is a Late Ordovician to Middle Silurian geologic formation in the Ozark Plateaus of Arkansas.[1] The name was introduced in 1894 by Henry Shaler Williams in his study of Arkansas.[2] Williams designated a type locality at what was known as the Cason tract and mine, near Batesville, Independence County, Arkansas, however, he did not assign a stratotype. As of 2017, a reference section has not been designated for this unit.

Cason Shale Stratigraphic range: Ordovician-Silurian
Type	Formation
Unit of	none
Underlies	Brassfield Limestone
Overlies	Fernvale Limestone
Thickness	up to appx. 23 feet[1]
Lithology
Primary	Shale
Location
Region	Arkansas
Country	United States
Type section
Named for	Cason tract and mine, near Batesville, Independence County, Arkansas
Named by	Henry Shaler Williams[2]

Paleofauna

Conodonts

Acodus A. inornatus[3] A. unicostatus[3] Ambalodus A. triangularis[3] Amorphognatus[3] Belodella B. flexa[3] Belodina B. inclinata[3] B. ornata[3] Carniodus[3] Cordylodus C. delicatus[3] C. flexuosus[3] Distacodus D. mehli[3] D. posterocostatus[3] D. procerus[3]

Distomodus D. kentuckyensis[3] Drepanodus D. homocurvatus[3] D. simplex[3] Eoligonodina E. delicata[3] Hadrognathus H. staurognathoides[3] Hindeodella H. equidentata[3] Keislognathus K. gracilis[3] Ligonodina L. egregia[3] L. silurica[3] Neoprioniodus N. bicurvatoides[3] N. planus[3]

Oistodus O. venustus[3] Ozarkodina O. gaertneri[3] O. tenuis[3] Paltodus P. multicostatus[3] P. trigonius[3] Panderodus P. gracilis[3] P. miseri[3] P. simplex[3] P. sulcatus[3] P. unicostatus[3] Phragmodus P. undatus[3] Plectospathodus P. extensus[3] Prioniodina P. irregularis[3]

Pterospathodus[3] Scolopodus S. insculptus[3] Spathognathodus S. manganiferus[3] S. procerus[3] S. sweeti[3] S. wolfordi[3] Tetraprioniodus T. superbus[3] Trichonodella T. brassfieldensis[3] T. carinata[3] T. diminuta[3] T. exacta[3] T. variflexa[3] Zygognathus Z. mira[3]

See also

• List of fossiliferous stratigraphic units in Arkansas
• Paleontology in Arkansas

References

1. McFarland, John David (2004) [1998]. "Stratigraphic summary of Arkansas" (PDF). Arkansas Geological Commission Information Circular. 36: 7. Archived from the original (PDF) on 2016-12-21. Retrieved 2018-01-11.
2. Williams, Henry S. (1894). "On the age of the manganese beds of the Batesville region of Arkansas". The American Journal of Science. 3rd Series. 48: 325–331.
3. Craig, William (1968). The stratigraphy and conodont paleontology of Ordovician and Silurian strata, Batesville district, Independence and Izard counties, Arkansas (PhD). The University of Texas.