1. Accumulation: In ancient swampy areas, large amounts of plant material, such as trees, ferns, and mosses, grew and died. The waterlogged environment prevented the material from fully decaying.
2. Burial: Over time, layers of sediment, like mud and sand, buried the plant material. The weight of these layers pressed the organic matter down, squeezing out water and air.
3. Transformation: Under pressure and heat, the plant material underwent a series of chemical and physical changes. The complex organic compounds in the plants were broken down into simpler molecules, resulting in the formation of coal.
4. Coal Formation: The transformation process leads to different types of coal, with varying levels of carbon content:
* Peat: The first stage, a soft, brown, partially decayed organic material.
* Lignite: A soft, brownish-black coal with a relatively low carbon content.
* Bituminous Coal: A harder, black coal with a higher carbon content.
* Anthracite: The highest-grade coal, with a very high carbon content and a shiny, black appearance.
The type of coal formed depends on the conditions of burial and the length of time the process takes. It typically takes millions of years for coal to form.
