Carboniferous Cunundrum.

[JimB88]

This will sound like a dumb question. But keep in mind that all my previous fossil expertise came from the Middle Ordovician of N.Illinois.

Is it unusual to find marine fossils in shale directly associated with coal? Shouldn't there be plant fossils from there as well - after all coal is formed from plant material. My question stems from the frustration of finding that site hoping for a plant that I can say "hey, thats pecopteris (or insert plant name)" or some such thing and only finding small unidentifiable fragments and some wood impressions. Would finding the exact layers adjacent to the coal be more productive? Would checking the coal itself be productive?

I realize that a lot of this depends on the environ at the time of deposition and the type of plants that existed there.

Thanks for enduring my questions.

[Guest N.AL.hunter]

I am no expert,but my experience has shown me:

Not common to find marine fossils in layers directly in contact with coal.

Common to find whole coal mines with nothing more than plant fragments.

Usually not too much found in the coal itself, only in the sedimentary rocks in contact with the coal.

[Terry Dactyll]

Jim..... If you can imagine great area's of forestation that initially produced the coal and also river deltas rich in vegetation around the edges that are constantly changing as sediments are washed down from the supercontinent... what was once a waterway becomes land and what was once land gets washed away and becomes part of the river channel as vast ammounts of rainwater make there way down into the ocean.... In the timescale we are talking about this could happen many times..... Maybe the area your talking about was situated more towards the ocean and through fluctuations or ultimately rises in sea level.... your landmass follwing forestation actually became seabed.....maybe! lol.....

[glacialerratic]

Terry is right on the money.

In IL., there was an ocean to the West/SW of the Mazon area. There were several sea level rises and falls over something like a 10 to 20 m.yr. period-- sea rise=coal bed formation/fall=swamp, more vegetation for future coal beds.

So yes, you can find marine organism in shale directly above/below coal.

[JimB88]

Terry is right on the money.

In IL., there was an ocean to the West/SW of the Mazon area. There were several sea level rises and falls over something like a 10 to 20 m.yr. period-- sea rise=coal bed formation/fall=swamp, more vegetation for future coal beds.

So yes, you can find marine organism in shale directly above/below coal.

Thanks guys, that makes sense. Rapid deposition over the swamp deposits would be needed to form coal. Im still determined to find some recognizable plant fossils (I know they are around here, I know people who have collected them - but they wont share the location! )

[RomanK]

This will sound like a dumb question. But keep in mind that all my previous fossil expertise came from the Middle Ordovician of N.Illinois.

Is it unusual to find marine fossils in shale directly associated with coal? Shouldn't there be plant fossils from there as well - after all coal is formed from plant material. My question stems from the frustration of finding that site hoping for a plant that I can say "hey, thats pecopteris (or insert plant name)" or some such thing and only finding small unidentifiable fragments and some wood impressions. Would finding the exact layers adjacent to the coal be more productive? Would checking the coal itself be productive?

I realize that a lot of this depends on the environ at the time of deposition and the type of plants that existed there.

Thanks for enduring my questions.

Hi Jim, answer on your question is here. Pay please attention to the Ice Age Sea Level Oscillations and Coal Deposits part. Regards, Roman

[JimB88]

Thanks Romank, that was helpful.

[Guest N.AL.hunter]

"repeating stratigraphic levels of peat bogs that later became coal, separated by layers of fluvial rocks like sandstone and shale when the deltas were building, and marine rocks like black shales and limestones when rising seas drowned coastlands." From the West Virginia site above.

Like I said, marine layers in direct contact with coal is not common. Direct contact is usually with lacustine deposits and not marine.

[JimB88]

"repeating stratigraphic levels of peat bogs that later became coal, separated by layers of fluvial rocks like sandstone and shale when the deltas were building, and marine rocks like black shales and limestones when rising seas drowned coastlands." From the West Virginia site above.

Like I said, marine layers in direct contact with coal is not common. Direct contact is usually with lacustine deposits and not marine.

It possibly could have been a brackish environ as well. The other possibility is the brach's Im finding were actually freshwater.