Seriously, I slept through most of my geology classes. (Remember Ben Stein as a science teacher? I had him for geology.)
Is it possible or reasonable that some or most petroleum is left over from early, prebiotic tar formation? Or is petroleum associated with later strata? Isn't there a guy named Gold who believes petroleum is abiotic?
It's times like this I wish I'd payed attention to what my teacher tried to tell me.
LOL! We have an early leader for 'funniest one-liner of the week'.