I just ran across a video of Kurt Wise talking about his floating forest hypothesis regarding the origin of coal seams. From memory, his main lines of evidence for this are:
- Coal too flat (top, bottom, and benches in the middle) to have been formed from a gradual process
- Plants in coal have a different root system from modern plants - the only similar root system are plants which grow entirely in water
- Fossil sequence similar to sequence of habitats in quaking bogs - smaller moving towards larger, and semi-aquatic moving towards amphibians in animals
Anyway, I think he was only referring to certain coal beds, not all coal beds. Nonetheless, based on the biomass, he was estimating that there was an entire pre-flood continent-sized floating forest which got buried. It is very interesting!