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he energy stored in coal and petroleum originally came to the earth from the sun. The bulk of the present-day supplies was laid down some 200 to 600 million years ago, when tropical conditions were widespread. Lush, swampy forests produced huge trees; warm coastal seas swarmed with microscopic forms of life. When these organisms died, much of their tissue was recycled as it is today — through scavenging and decay. But a significant amount of dead plant and animal material was covered with mud, which prevented complete decomposition.

With the passage of time, layer upon layer of the fine sediment was deposited over the once-living material; the sheer weight turned the sediments to rock. Sandwiched between the layers, both coal and petroleum were produced and preserved under pressure. Coal was formed mostly of giant fern-like plants that have only small counterparts today. Coal may still be forming here and there on earth, but conditions are not right for the production of significant quantities.

1) Energy stored in coal, petroleum came from sun

2) bulk of present-day supplies – laid down some 200-600 million years ago

3) coastal seas teemed with microscopic forms of life in tropical conditions – these organisms
died –  tissues recycled through scavenging and decay

4) dead plants and animals covered with mud, prevented from total decomposition

5) layers of sediments- weight accumulation – sediments turned into rocks – pressure built – formation of coal and petroleum preserved under pressure

6) today, conditions unsuitable for coal – production not in significant quantities

1) Energy stored in coal, petroleum came from sun

2) bulk of present-day supplies laid down some 200-600 million years ago

3) abundance of microscopic forms of life in tropical conditions

4) organisms died – tissues recycled through scavenging and decay

5) prevention from total decomposition- considerable portion of dead animal and plant remained covered with mud

6) over the years, sediments hardened to form rocks

7) production of coal, petroleum under pressure

8) present day conditions not suitable for coal-formation

1) Energy stored in coal and petroleum came from sun
    - bulk of present-day supplies laid down some 200-600 million years ago

2)  abundance of microscopic forms of life in tropical conditions
     -Dead organisms
     -Tissues recycled through scavenging and decay

3) Total decomposition of considerable dead plants and animals prevented by being covered with mud

4) Formation of rocks as the sediments hardened

5) Coal, petroleum produced by compression of matter between rocks

6) Present times, unsuitable for coal formation

- Storage of energy from sun in coal and petroleum

- Deposit of bulk supplies 200-600 million years ago

- Abundance of microscopic forms of life in tropical conditions

- Death of microscopic life forms leading to recycling through decay

- Prevention of total decomposition by significant amount of dead plants and animals being covered with mud

- Hardening of sediments, over the years, led to rock-formation

- Production of coal, petroleum by compression of matter between rocks

- Unsuitability of present-day conditions for coal-formation