Ancient plant preserved in the Arkansas River Valley
(stylus approximately 4 inches long)
Plant fossils in Arkansas are mostly preserved in rocks of Mississippian and Pennsylvanian age. Most plants grew in swampy areas, eventually died, and accumulated to ultimately form coal. Because vast coal deposits are recognized worldwide, the Mississippian and Pennsylvanian systems are referred to as the Carboniferous Period or the coal measures. This ancient tree-sized plant called Calamites was more abundant on higher ground along levees and floodplains of rivers than in swamps. This picture shows a branch that would have been positioned on a segmented trunk at intervals. This fossil was discovered in the McAlester Formation.