>I was under the impression that most coal was made up of the remains of
>lycopyte and sphenite material. This would be mosly extinct tree-form
>lycopods and hortails.
Of course you are correct for the Paleozoic coals in your neighborhood.
Maybe my impressions are wrong. What is the
>consensus on how much dicot (flowering plant) wood there is in the coal
>record. My guess would be only the most recent coals (mostly soft brown
>coals if I remember my coal terminology) would contain any dicot wood.
The dominant coals in our area are Tertiary, and those in the west are
Cretaceous. In any case no one answer will do for all coals.
The point here is that in general lycopods and sphenites likely had very porous
>wood (much like todays tree ferns and palms) and thus the compression
>factor was very high, as opposed to dicot (flowering plant) wood which has
>a high density/specific gravity.
>On a similar note, the vast amount of fern-like fossilized material would
>seems to imply that the world was covered prodominantly with fern-like
>plants. Am I way off here in my impression of the fossil record?
Your impression based on the Carboniferous coals is correct for your part of
the country certainly. Not so for our coals, which are largely angiospermous.
But even for Carboniferous coals i think most of the estimates of
compression are exaggerated. The figures are not that hard to calculate,
just dry weight (generally 10-20% of wet weight) times .5 (to get rid of
oxygen) times 1.3 (to account for density increase). What we are talking
about in Paleozoic coals is not the living flora but the accumulated
biomass, already largely deflated (such as calamite stems) by decay processes.
Art
http://chadwicka.swau.edu