15 July 2015

Years ago when I first hiked the Ferncliff Trail at Ohiopyle I was puzzled by this pattern on the rock beneath my feet.

In those days there were no interpretive signs nearby so I tried to make sense of it as best I could.  I decided it was a motorcycle track, but I couldn’t figure out how the vehicle had gotten there and why it had run from the cliff into the river.

Duh!  Motorcycles don’t leave tracks in rock.  It’s a fossil!

This Lepidodendron is one of six kinds of fossils found along the river’s edge now listed on an interpretive sign as: Cordaites leaves, Lepidodendron scale, giant Calamites, Psaronius, a giant dragonfly and Sigillaria.

Though I’ve seen the other ones this is the fossil I like the best.

Lepidodendron was a tree-like plant with scales on its trunk that grew as high as 100 feet tall.

It lived and died in the Carboniferous (coal making) era.  If the tree had fallen in a swamp it would have become peat and then coal, but it happened to fall on sand so the patterns of its scaly trunk were preserved in rock.

Not far away is one of Lepidodendron’s last living relatives: Lycopodium or groundpine. Only 6-12 inches tall, it provides a visual hint of its ancestor’s appearance including the scales on its trunk and branches.

The past and present are near each other at Ferncliff Peninsula.

(fossil photos by Kate St. John. Drawing of Lepidodendron and photo of Lycopodium from Wikimedia Commons; click the images see the originals)