Hn
A H horizon of the topsoil with current peat formation from the dead remains of peat-forming mosses and peat-forming higher plants. In the fluctuating area of bog, stagnant water or groundwater and temporary overflow. The organic matter consists of extremely low to completely humified plant remains [n from new].

1. organic carbon content ≥ 15 mass % and
2. formed from the remains of peat-forming plants.
3. Saturated with water all year to predominantly saturated or flooded and
4. formed under predominantly anaerobic and only very briefly aerobic conditions and
5. peat formation through incomplete decomposition of plant remains and
6. dense elastic network of living, aerial plant roots or basal sections of mosses and
7. no segregation structure and
8. current vegetation dominated by peat-forming plants.

Modified Hn horizons

Hfn

A modified Hn horizon, peat-forming horizon, permanently waterlogged or flooded, predominantly anaerobic with very weak aerobic conditions due to aerial roots or water table fluctuations; very clearly recognisable plant structures in the extremely low or moderately humified peat [f from fibrum, fibre].

1. organic carbon content ≥ 15 mass % and
2. formed from the remains of peat-forming plants.
3. Saturated with water all year to predominantly saturated or flooded and
4. formed under predominantly anaerobic and only very briefly aerobic conditions and
5. peat formation through incomplete decomposition of plant remains and
6. dense elastic network of living, aerial plant roots or basal sections of mosses and
7. no segregation structure and
8. current vegetation dominated by peat-forming plants.
9. degree of humification according to von Post H1 – H4

Hfn-horizon, extinct spagnum moss, low grade of humification, humus form:  Dystric F-Moor,            ©Gerhard Milbert

Hen
A modified Hn horizon, peat-forming horizon, seasonally waterlogged or flooded, predominantly anaerobic with seasonally weakly aerobic conditions due to aerial roots and water table fluctuations; weakly to indistinctly recognisable plant structures in medium to highly humified peat [e from hemic].

1. organic carbon content ≥ 15 mass % and
2. formed from the remains of peat-forming plants.
3. Saturated with water all year to predominantly saturated or flooded and
4. formed under predominantly anaerobic and only very briefly aerobic conditions and
5. peat formation through incomplete decomposition of plant remains and
6. dense elastic network of living, aerial plant roots or basal sections of mosses and
7. no segregation structure and
8. current vegetation dominated by peat-forming plants.
9. degree of humification according to von Post H5 – H7

Hhn         

A modified Hn horizon, peat formation horizon, predominantly water-saturated or flooded during the course of the year, with intermittent aerobic conditions due to aerial roots and water level fluctuations or aeration; very indistinct or no longer recognisable plant structures in very highly or completely humified peat [h from completely humified = sapric].

1. organic carbon content ≥ 15 mass % and
2. formed from the remains of peat-forming plants.
3. Saturated with water all year to predominantly saturated or flooded and
4. formed under predominantly anaerobic and only very briefly aerobic conditions and
5. peat formation through incomplete decomposition of plant remains and
6. dense elastic network of living, aerial plant roots or basal sections of mosses and
7. no segregation structure and
8. current vegetation dominated by peat-forming plants.
9. degree of humification according to von Post H8 – H10

Fen with nHhn-horizon,
waterhead of the river Eder, Gemany,
© Geological Survey North Rhine-Westphalia