During the mid-to-late Carboniferous the state gradually became a swampy environment.

During the Carboniferous period the state became a swampy environment where lush vegetation included trees more than 50 feet high.

Rivers and streams drained into the basin, which became a swampy environment.

Carboniferous Pennsylvania was a swampy environment covered by a wide variety of plants.

It is made up of siltstones and claystones, red in color, which have been interpreted as a swampy environment.

It can even grow submersed in swampy environments.

This swampy environment formed many coal deposits which were mined in the late 19th and early 20th centuries.

This may have led some paleontologists to believe that the animals had died in swampy environments.

This probably helped rhizodonts detect prey in the turbid, swampy environment where they lived.

During the mid-to-late Carboniferous, the state became a swampy environment, home to a rich variety of plants including ferns and scale trees.