McDonough County
In some of the small underground mines near Colchester, the shale overlying the Colchester (No. 2) Coal contains ironstone concretions similar to those from northeastern Illinois. More than 50 species of plant fossils have been reported, but they were collected many years ago from spoil heaps at the mines. Beds of the same age crop out widely in other localities in western Illinois and may contain plant fossils.
Plate 4
Sphenopteris ⅗× Linopteris ⅗× Neuropteris ½× Odontopteris ⅗× Cycopteris ½× Alethopteris ⅗× Alethopteris ⅗× Odontopteris ½× Alethopteris ⅗×