The dark fibrous material created when the decomposition of dead plants and trees fail to keep pace with the production of organic matter is known as:
Peat
Peat is a dark fibrous material created when the decomposition of dead plants and trees fail to keep pace with the production of organic matter. It is partly decomposed vegetable matter, found in bogs and sometimes burned as fuel or mixed into the soil in order to improve the growing conditions. Peat is the first stage of formation of coal.