Textures and conditions of formation of Middle Pennsylvanian coal balls

Calcareous, fossiliferous nodules occasionally occur within coal seams of Middle Penn-sylvanian age and may contain a wide variety of remarkably well-preserved plant taxa and sometimes marine animal shells. Textural variability within these nodules, termed coal balls, suggests that the energy of transport of organic constituents varied from mild current activity to turbid wave or perhaps tidal movements. The environment of coal ball deposi-tion may have been in coastal marshes similar to the southwest Florida mangroves, where repeated influxes of marine sediment-bearing water provide both the energy source for agitation and mixing of organic detritus and the proper geochemical conditions for car-bonate diagenesis