2.3.14 (HL)—Fossil fuel formation

Coal mainly formed from buried land plants; oil and natural gas mainly formed from buried marine organic matter under suitable geological conditions.

Low oxygen, burial, pressure, heat and long time limited decomposition and transformed the material. These conditions were uneven, so not every deposit forms the same fuel.

A coal seam points to ancient plant-rich wetlands; an oil source rock points to organic-rich marine sediments rather than simply ‘old dead matter’.

Fuel type depends on original biomass and formation environment, not age alone.

Geological time is necessary but not sufficient; source material and preservation conditions matter.