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Firstly, I would prefer it if you e-mailed me with these sorts
of questions, as they can be a bit complex to answer.
Coprolites
are preserved under special curcumstances, such as rapid burial
or falling into an environment in which no scavenging organisms
are present. sometimes, the content of the coprolite is sturdy
enough to be preserved. They tend to be rare in the Wealden, but
one or two are known.
The
colour differences between the beds is due to the conditions they
were under prior to burial. The grey beds were anoxic, with early
sulphide reduction taking place. this in turn leads to a low Fe
value, less than 2%. Sulphide ions are abundant, due to the equally
abundant organic material, such as wood. The red beds were much
dryer, and are actually iron rich, with haematite being concentrated
within the clay particles, causing the red colour.
I
hope this is helpful, and that you get your essay in on time.
DW
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