The Devonian in Pennsylvania, US

Paleontology and geology

The Devonian Period witnessed another great episode of mountain building, the Acadian Orogeny. Rivers poured sediment into the sea, building vast deltas and flood plains. The muddy sea floor was home to brachiopods and to tall, flower-like crinoids. Land plants became more common and their fossils can sometimes be found in Late Devonian rocks in central Pennsylvania.