How do I decide what resources are where?

[Adversary]

The most famous coal fire I knew about was the one in Centrailia, Pennsylvania. It was started accidentally when a trash dump was burned. The dump was in contact with an exposed coal seam and has been burning since 1961. Ironically, the fire was started by five firefighters. This fire gets it's oxygen from the exposed seam and from mine shafts. The town was evacuated because of sinkholes and the poisonous fumes released by burning coal.

But the longest burning fire is in Australia. Burning mountain has been burning for about 6,000 years. Again it was started in an exposed coal seam.

These fires do not require much oxygen, they smoulder more than burn so they tend to last for a very long time. Coal fires can get enough oxygen through cracks, mine shafts, sinkholes or from surface exposure. The deeper fires stay burning because the heat is so efficiently trapped by the earth above it, so even if the oxygen gets consumed in the short run, the heat and fuel are still present waiting for a breath of oxygen to reignite.

There are thousands of coal fires burning worldwide.

[Adversary]

There is one example of a natural, natural gas fire that I found. It is in Yanartas, Turkey. There are several fires burning over a 5000 squad meter area which have been burning since ancient times. I found a Wikipedia post that I found humorous: "In ancient times sailors could navigate by the flames, but today they are more often used to brew tea."

[Adversary]

I have a correction for the coal section I added. Most coal does not need pressure to form, only heat and time in an environment low in oxygen. It is possible (but very rare) for coal to form near the surface. Anthracite is the only coal that needs pressure to form.