Some coal is too thoroughly cooked to show traces of the original
constituents, and some coal consists largely of algal remains, but I do not
know the proportions.
Most trees fall down after they die, and the roots may rot. Roots do not
need to be very deep in a swamp, since water is at the surface. There
should be relevant information from modern swamp cores, although for the
Carboniferous we don't know the exact physical properties of tree-size club
mosses, and predicting their decay is also complicated by not knowing
exactly which organisms were present to help decay.
Tree bark should not be the main constituent in the catastrophic
model-tree wood should be more significant.
The drainage paths in many swamps move around enough to have limited
long-term preservation potential.
A feature of some lignites that supports an allocthonous but slow origin is
the presence of large bivalve borings in the fossil wood. It takes a while
for clams to grow as big as those in the Drumheller region in Alberta or
around Tar Heel here in North Carolina.