The peat swamps were interwoven with meandering river channels which deposited silt and mud over the fallen organics. We also find cycles in alot of places where the coal seams are squashed between thick layers of marine sediments. These are called cyclothems.
True depostional rates were anything but uniform. In some places, fossilized trees are observed in surface mine highwalls buried in standing position, attesting to rapid burial. While in other spots, the coal seams are several meters thick, displaying slow even deposition. In general, every twelve inches of coal thickness represents approximately 10 000 years of continuous peat accumulation.
The fossilized trunk of a Lepidodendron