What is the formation process of coal?

Coal formation primarily involves the transformation of organic material, specifically plant matter, into peat, which then undergoes physical and chemical changes over geological time under the influence of heat and pressure. This process begins with the accumulation of plant debris in swampy or marshy environments, where conditions are conducive to preserving organic matter. Over millions of years, layers of sediment build up over the peat, exerting pressure that causes the organic material to undergo a process known as "coalification."

During coalification, peat is transformed into different types of coal—lignite, sub-bituminous, bituminous, and anthracite—each representing varying degrees of heat and pressure applied over time. As heat and pressure increase, volatile compounds are driven off, and carbon content increases, resulting in higher energy content and a denser material, which is characteristic of coal.

This process is fundamental to understanding natural resource formation and is significant for energy production and environmental studies. The other options refer to processes that do not correctly describe the coal formation process: for instance, the first choice involves non-organic materials, the second focuses on marine organisms rather than terrestrial plants, and the last option, while it mentions plant matter, does not capture the critical stages of peat conversion through heat and pressure