Coal, coke and oil as ancient fuels

[M. Demetrius]

Petroleum would only be accessible in the rare places where it comes to the surface on its own. The had no means to drill deep enough to get oil, I think, except maybe from tarpits, which do exist in scattered places.

Probably, the tar had better uses than to be burned. It's at least as good as pitch for sealing boats, etc., just not as easily available.