Silica Formation Units 20-23 (Devonian of the United States)

Where: Ohio (41.7° N, 83.7° W: paleocoordinates 36.4° S, 31.0° W)

• coordinate based on nearby landmark

• local area-level geographic resolution

When: Silica Formation, Givetian (387.7 - 382.7 Ma)

• group of beds-level stratigraphic resolution

Environment/lithology: marine; gray, argillaceous limestone

• Overall sequence: Bioclastic limestone; argillaceous limestone; shale. This unit: 20: "limestone, argillaceous, dark-gray"; 21: "limestone, massive, slightly argillaceous, dark-gray, many marcasite concretions, harder than units below and above"; 22: limestone, massive, argillaceous, dark-gray, some marcasite concretions"; 23: "limestone, massive, argillaceous, dark-gray...many marcasite concretions, grading into units below and above but harder than either"

Primary reference: R. V. Kesling and R. B. Chilman. 1975. Strata and megafossils of the Middle Devonian Silica Formation. University of Michigan Papers on Paleontology 8:1-408 [M. Foote/M. Foote/M. Foote]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 38471: authorized by Michael Foote, entered by Michael Foote on 21.04.2004

Creative Commons license: CC BY (attribution)

Taxonomic list

 Fenestrata -
 Trepostomida -
 Cyclostomata - Hederellidae
 Cryptostomata - Hyphasmoporidae
 Strophomenida - Strophodontidae
"Strophodonta spp." = Strophomena (Strophodonta)
"Strophodonta spp." = Strophomena (Strophodonta) Hall 1852
 Spiriferida - Mucrospiriferidae
 Rhynchonellida - Leiorhynchidae
Anthozoa indet. Ehrenberg 1834