Description

The Mazon Creek area fossils are found mostly in siderite concretions but may also be found in shale as black carbon compressions. The age of the fossil plant is Desmoinesian, Middle Pennsylvanian of the generalized Carboniferous period, about 307 million years ago. This siderite fern is from the Braidwood biota of terrestrial fossils of Mazon Creek, near Joliet, IL.

Fossils pairs vary depending on shape and size.

sizes range from 1.5″- 2″ in width and 3.5″- 4″ in length.