[Tolerance Sucks Rocks]

Oil is made by methane percolating up from the earths core, becoming trapped in rock formations and being compressed into oil over time. This is the current view of competent geologist, very simplified.

I thought the Earth's core was made up of iron and maybe nickel as well. When did the thinking on the core's composition change?

[Dan Evans]

I thought the Earth's core was made up of iron and maybe nickel as well. When did the thinking on the core's composition change?

There are meteorites that contain some percentage of carbon and hydrogen and so it would be surprising if the earth's core had none. It wouldn't take very much at all to account for the oil deposits since the crust is a tiny fraction of the earth's mass.