Gleysols occur throughout the world where groundwater comes near to the surface, causing soils to become wet for a prolonged part of the year. They are particularly abundant in the low-lying river basins.
Soils having gleyic properties (properties associated with prolonged wetness) within 50 cm from the soil surface. They have no diagnostic horizons other than an anthraquic, histic, mollic, ochric, takyric, or umbric horizon at the surface, or an andic, calcic, cambic, gypsic, plinthic, salic, sulfuric, or vitric horizon within 100 cm from the soil surface.
Gleysol with a fluctuating groundwater regime, Germany; permanent reduction in the grey part (bottom), alternating oxidation and reduction in brownish parts (middle) (Eutric Gleysol; ISRIC reference soil DE 006)