The marshes represent other small component of hydrosphere, intermediate between lakes and underground waters distinguished by the special selection of vegetation, adapted to superfluous humidifying and lack of oxygen in water. The marshes of moderate and high breadthes are traps of organic carbon, in which its accumulation and burial is done. Usually it is overmoistened superficial layer of the soil, in which the rests of vegetation forming peat collect. To them overmoistened soil more characteristic for tropical areas, where the peat does not collect as the organic substance basically is decomposed adjoins. The general area of marshes and overmoistened soil is estimated in 3 million km2.
