Image: Fossiliferous flint (Upper Mercer Flint, Middle Pennsylvanian; Nellie West Outcrop, Coshocton County, Ohio, USA) 1 (31803128551)

Description: Fossiliferous flint (chert) from the Pennsylvanian of Ohio, USA. (9.5 cm across at its widest) "Flint" is the official gemstone of Ohio. Flint is actually chert (the two terms are synonymous, despite what anyone else might say), a cryptocrystalline, quartzose sedimentary rock. High-quality, colorful, multicolored, and multipatterned flint is moderately common at some Ohio localities. A couple famous flint occurrences in east-central Ohio include the Vanport Flint at Flint Ridge and Nellie Blue Flint in Coshocton County. The rock shown above is from the Upper Mercer Flint, a somewhat persistent horizon of chertified marine fossiliferous limestone in east-central and eastern Ohio called the Upper Mercer Limestone. The Upper Mercer is usually a black flint with whitish speckles (= often body fossils and fossil fragments). This sample has a fossil solitary rugose coral exposed in transverse cross-section. The light-colored rind at top is non-chertified Upper Mercer - in other words, limestone. Classification: Animalia, Cnidaria, Anthozoa, Rugosa Stratigraphy: Upper Mercer Flint (= chertified Upper Mercer Limestone), upper Bedford Cyclothem, upper Pottsville Group, Atokan Series, lower Middle Pennsylvanian Locality: Nellie West Outcrop, western Jefferson Township, western Coshocton County, east-central Ohio, USA
Title: Fossiliferous flint (Upper Mercer Flint, Middle Pennsylvanian; Nellie West Outcrop, Coshocton County, Ohio, USA) 1 (31803128551)
Credit: Fossiliferous flint (Upper Mercer Flint, Middle Pennsylvanian; Nellie West Outcrop, Coshocton County, Ohio, USA) 1
Author: James St. John
Usage Terms: Creative Commons Attribution 2.0
License: CC BY 2.0
License Link: https://creativecommons.org/licenses/by/2.0
Attribution Required?: Yes