Coal is made from the remains of plans and trees that lived about millions of years ago. They delayed and get buried to the ground and were compacted under rock layers. It is a hard brown or black rocklike mineral substance that is used for burning to generate heat. It is one of the most abundant mineral fuels on the earth and the leading source of electrical power in most industrialized countries.
There are a number of theories that came up as to where goal is produced or where it originated. The first one is ancient swamp forest which stated that even though coal resembles like rock, it is different from other mineral substance that is found in the ground. According to this theory, coal is made up of the plant remains which existed hundreds of millions of years ago. The remains of the ancient plans are being constantly found in coal beds. If small pieces of coal would be examined using a microscope, the patter of the fibers forming the original plant can be visible.
The second theory is sinking land. In the carbon or coal bearing period, most of the parts of the earth were rising or sinking slowly. The land underneath the swamp forests slowly sank, allowing the seawaters to flow in, covering them. The water pressure squeezed the beds of pear that caused them to solidify and dry. The sediments on the bottom of the sea slowly turned to rock, which pressed the peat even more.
The last one is the formation of coal beds. In most areas, the land rise and fell several times. Such movement has caused the formation of layer after layer of coal that is separated by the layers of sedimentary rock. The increased pressure was caused by more dock deposits that formed bituminous coal. In areas where mountains are formed, the coal beds had been compressed to the hardest type of coal that was recognized as anthracite. The coal beds, known as seams can be 400 feet thick or 2.5 cm or less thin.
Regardless of how it is formed, coal is one of the very important products being used today in terms of heat and electricity generation.