Here is an amazingly well preserved Pennsylvanian Alethopteris Fern Leaf block. Alethopteris is a prehistoric plant genus of fossil seed fern that developed in the Carboniferous period around 360 to 300 million years ago. It is from the famous coal mining areas of Pennsylvania. There are several species of Ferns found in the fossil floral record.
The Carboniferous Period of Illinois was mostly a hot steamy jungle and swamps. The plants and animals were buried in sediment without much Oxygen and began to fossilize.
The Pennsylvanian Alethopteris Fern fossil was found within the sediments of discarded rock. Because it was of no use to the coal companies it was tossed onto a pile of unusable rock. The shale is formed when fern leaves fall to the ground and are quickly covered by sediment. Because of the low level of oxygen the leaves are preserved as impressions.
This Pennsylvanian Alethopteris Fern, Alethopteris block displays beautifully. The white fern impressions set off nicely from the black shale. This block is 4 1/2 inches long and 6 inches wide. It will make a great cabinet piece.
Pennsylvania is famous for these fossils but the areas where they were collected is now off-limits they are harder to obtain. Because of coal mining activity they were brought to the surface.