* Organic Origin: Coal starts as a vast accumulation of dead plants, mostly ferns and trees, in swampy or boggy areas. These environments are characterized by abundant water, limited oxygen, and the presence of decaying organic matter.
* Burial and Pressure: Over millions of years, these layers of plant material are buried under sediment (sand, mud, etc.), leading to increased pressure and temperature.
* Chemical and Physical Changes: As the plant material is buried deeper, bacteria break down the material, releasing gases and leaving behind a carbon-rich substance called peat. Continued pressure and heat transform the peat into coal, squeezing out water and other volatile compounds.
* Stages of Coal Formation: The process of coal formation goes through various stages, each with different properties:
* Peat: The initial stage, consisting of partially decayed plant material.
* Lignite: A soft, brownish-black coal with a high moisture content.
* Bituminous coal: A harder, black coal with a higher carbon content and lower moisture content.
* Anthracite coal: The highest-grade coal, with the highest carbon content and the lowest moisture content.
Therefore, the formation of coal involves the accumulation, burial, and transformation of organic matter within a sedimentary environment, making it a sedimentary rock.
