Pinnacle of fossiliferous Ordovician Jonesboro Limestone that crops out in the alluvial plain. Cows give scale of a typical outcrop.
Jonesboro Limestone is a light gray weathered, bedded limestone defined by clay partings, fossil horizons, sand grains, and chert stringers. Locally it is a massive and brecciated dolomite. The limestone contains both micro- and macro-fossils.