This week's Friday Field Photo is from Pennsylvanian aged (~300 million years old) strata exposed in southern West Virginia. Actually, it's a slab of fine-grained sandstone used to construct a pathway very close to Pennsylvanian strata. It's certainly possible it's from very far away, but I'm going to guess that it's from nearby stone quarries of very similar aged-rock.
Regardless of its age, it shows a very nice example of a trace fossil. That is, not a fossil of biomineralized body parts (shells, bones), but the evidence of life preserved as a track in the sediment -- a preserved footprint is a trace fossil. In this case, some small organism 300 million years ago crawled across the sea floor leaving this sinuous trace behind.
The study of trace fossils -- called ichnology -- is very useful for reconstructing ancient environments. If you're not already, I recommend subscribing to Anthony Martin's blog and Twitter feed -- @ichnologist -- to learn much more about how these squiggly little tracks help us understand Earth history.
Happy Friday!
Image: Trace fossils in West Virginia strata / from my collection
