Formation of Fossil Fuels: Coal and Petroleum Genesis: A Visual Explainer
A single side-by-side infographic contrasting the six-stage coalification pathway (plant debris to anthracite) with the parallel petrogenesis pathway (marine organisms to a trapped oil/gas reservoir).
📌 Revision Pointers
Coal rank sequence: Peat → Lignite → Sub-bituminous → Bituminous → Anthracite (rising carbon & energy content with burial depth).
Petroleum sequence: Source rock (kerogen) → Heat & pressure (~60–120°C, catagenesis) → Migration → Reservoir rock → Cap rock & Trap.
Both require burial under sediment, anaerobic (oxygen-free) conditions, heat + pressure, and millions of years - but coal forms from land plant matter while petroleum forms from marine microorganisms.
Two clean labeled flowcharts tracing coal formation and petroleum formation stage-by-stage, with their shared geological requirements called out at the bottom.
💭 Conclusion
A recurring Prelims diagram topic - know the coal-rank order and the source rock/reservoir rock/cap rock/trap terminology for petroleum.