What happens in each step of coal formation?

Answer 1

From the beginning of time, occurring over millions of years....

1. leaves (leaf litter) fall upon the dirt (ground; Earth)
2. branches fall; trees fall upon the leaf litter
3. plants die under leaf litter and fallen branches / trees
4. the rains come
5. sunlight hits upon the saturated leaf litter, branches, and fallen trees
6. the pile begins to heat up from within, accelerating decomposition
7. winds blow dust around, adding new dirt to the decomposing warmed-up pile
8. fallen trees under the pile begin to rot
9. more leaves fall from trees
10. more branches fall
11. more trees fall
12. more rain
13. every day's sunlight keeps heating the pile
14. winds blow in more and more dirt
15. what is on top presses down on what is at the bottom
16. more leaf litter, branches, trees, rain, sunlight, winds...
17. the bottom of the pile, which is very hot inside the decomposing mess, begins to compact, eventually becoming coal
18. the cycle is continual...even today, coal is being compressed from under the ground
19. swampy areas in hot environments are more likely to make coal, as water is continually added to the mix and heat continues to build below the surface **
20. What kind of coal you get (anthracite or bituminous) depends on how many millions of years the pile of litter decomposed and "cooked" underground.

** Millions of years ago, the NE US to middle states was temperate and swampy. Water from the inland sea was still receding from the middle of the country. So, Pennsylvania, West Virginia, Ohio, Kentucky, Illinois, and Indiana had an abundance of coal made over many hundreds of millions of years, back in the era when glaciers were retreating and dinosaurs roamed.