Formation of fossil coal is the following stage after formation of peat. That peat could be carbonized, some conditions have to be met.
Conditions of formation of peat
To turn peat into coal, a lot of time is required. Peat layers gradually collected in peat bogs, and from above the earth grew with increasing number of plants. At a depth the difficult connections which are in the decaying plants break up to more and more simple. They are partially dissolved and carried away by water, and a part turns them into gaseous state, forming methane and carbon dioxide. Bacteria and various fungi inhabiting all swamps and peat bogs also play an important role in formation of coal as promote fast decomposition of vegetable fabrics. Over time in the course of such changes in peat carbon as the most resistant substance begins to collect. Eventually carbon in peat becomes more and more.
Important condition at accumulation in peat of carbon is the lack of access of oxygen. Otherwise carbon, having connected to oxygen, would turn into carbon dioxide and disappeared. The peat layers which are transformed to coal are isolated from air and the oxygen which is contained in it by the water covering them in the beginning, and the peat layers which from above are again arising from the decaying layer of plants and the new thickets growing on them.
Coal stages
The first stage is a lignite, friable coal of brown color, the most similar to peat, not the most ancient origin. The remains of plants, especially wood as it decays longer are clearly looked through in it. Lignite is formed in modern peat bogs of a midland, and consists of a cane, a sedge, a peat moss. Wood peat which is formed in a subtropical strip, for example, on swamps of Florida in the USA is very similar to fossil lignite. Brown coal is created at stronger decomposition and change of the vegetable remains. Its color black or dark-brown, in it residues of wood meet less often, and there are no remains of plants at all, it is stronger than lignite. When burning, brown coal generates much more heat as in it it is more carbonaceous connections. Over time brown coal turns into coal, but not always. Process of transformation happens only if the layer of brown coal falls to deeper layers of earth crust when there is a mountain building process. To turn brown coal into stone or into anthracite, very high temperature of bowels of the earth and big pressure is necessary. Remains of plants and wood can be found in coal only under a microscope, it shines, almost like the stone is heavy and strong. Black and brilliant coal under the name anthracite contains the greatest number of carbon. This coal is appreciated above everything as at combustion gives most of all heat.