How is compaction important in the formation of coal? i don't get it?

Question

i dont get it

Answer 1

Coal is formed from accumulations of plant materials. Most accumulations of dead plants will decompose and will not be preserved, but in places where the plants that later became coal formed, the plant remains often fell into water that was fairly acidic, with a pH below 4, so there was almost no biological activity to decay the plant material. Instead, as later geologic processes buried this plant material under deposits of mud and sand, the weight of the overlying sediments pushed water out of the layer of plant materials. Eventually hundreds and then thousands of feet of rock may accumulate and the weight of all of that rock creates pressure that compacts as many as fourteen feet of plant remains down to only one foot of coal. Temperature and chemical changes also take place that are driven partially by the change in pressure and resulting compaction. Without the compaction, coal would never form from plant remains. Different grades of coal such as lignite, sub-bituminous, bituminous, and anthracite all result from different amounts of compaction, or pressure.

Here is a basic diagram of the process:
http://waterquality.montana.edu/docs/photo/coalification.shtml
Here are descriptions of the ranks of coal:
http://www.appaltree.net/aba/coaltypes.htm

Answer 2

WITH OUT THE COMPACTING OF THE CARBONACEOUS MATERIALS THERE WOULD BE A MASS OF LOOSE PARTICLES. THE COMPACTION ALSO CAUSES TEMPERATURE ELEVATIONS NECESSARY FOR COAL FORMATION.