Podzol soil profile distinguished by having a surface mor (peaty) humus up to a maximum thickness of 30 cm, and usually with an iron pan at the top of the B soil horizons. The term occurs in most of the classification systems derived originally from the work of V. V. Dokuchayev, published in 1886. It has been superseded in the USDA soil taxonomy and podzols now fall within the order spodosols, but the term is retained as a reference group in the World Reference Base for Soil Classification.