I'm maybe about to get enmeshed in a discussion along these lines on another board. I can handle most of the questions, but I have one so far unanswered for myself: what are the likely precursors for 14C in ancient carbon? I can see some of the nirtogen in coal or petroleum being irradiated to 14C, as it is in the upper atmosphere, but how, say, in diamonds? Neutron capture by 13C? Or what?
Added in edit: There's usually more nitrogen than nirtogen in coal. Sorry.
[This message has been edited by Coragyps, 04-20-2004]