Formation of Fossil Fuels

Overview

• Topic: Formation of fossil fuels (coal, oil, natural gas).
• Timeframe: Formed over millions of years; therefore non-renewable.
• Key idea: Carbon in fossil fuels originally came from carbon dioxide absorbed during photosynthesis.

Coal: Formation and Conditions

• Source: Remains of ferns and trees in marshy wetlands.
• Decomposition prevented by lack of oxygen or acidic conditions.
• Process: Plant remains become buried under sediment, then compressed.
• Result: High pressure and temperature convert remains into coal.

Oil: Formation and Conditions

• Source: Plankton (tiny marine plants and animals) that die and settle on the seabed.
• Decomposition prevented by low-oxygen conditions in seabed mud.
• Process: Plankton remains are buried by sediment; heat and pressure convert them into crude oil.
• Location note: Oil forms in marine sediments.

Natural Gas: Formation and Relation to Oil

• Main component: Methane (a hydrocarbon).
• Source: Formed from plankton in a similar way to oil.
• Co-occurrence: Natural gas is often found near oil deposits because of similar origins.

Key Terms and Definitions

• Fossil Fuels: Fuels formed from ancient biological material over millions of years (coal, oil, gas).
• Non-renewable: Resource that cannot be replenished on a human timescale.
• Plankton: Tiny marine plants and animals; source material for oil and gas.
• Methane: Main hydrocarbon component of natural gas.
• Photosynthesis: Process by which organisms take in carbon dioxide and produce oxygen; original step that fixed carbon into organisms long ago.

Process Summary Table

Additional Points / Next Steps

• Burning fossil fuels releases the trapped carbon back into the atmosphere as carbon dioxide.
• Further study: Effects of burning fossil fuels on the planet (climate change topics covered in a later lesson).
• Practice: Review related questions in the provided exam workbook for consolidation.