Evidence in Support of a Limnic Subgroup in the Gelisol Order of US Soil Taxonomy.

SSSA 2009 Lorene Lynn Evidence in support of a limnic subgroup in the Gelisol order of US Soil Taxonomy. A soil of special interest was found along the Beaufort Sea Coast of Alaska. High volumes of coprogenous earth were discovered in deep organic Gelisols. A distinct feature of the soils at West Dock in Prudhoe Bay was the presence of coprogenous earth in over half of the soil profiles examined. Limnic soil was also observed in Cape Halket, which is east of Elson Lagoon and west of Prudhoe Bay. These limnic deposits ranged in thickness from 1cm to 46cm and were usually found at or around 30cm below the surface. Examination by microscope revealed that the soils were composed of a mix of coprogenous earth and partially decomposed organic materials. Currently in Keys to Soil Taxonomy, 10th ed., limnic deposits are only considered in the lower categories of Histosols and are considered common to organic soils. Gelisols frequently have deep organic horizons that extend well into the permfrost. The cold, wet conditions common to Gelisols are ideal for the genesis and preservation of limnic materials. In addition, organic Gelisols were formerly classified as pergelic Histosols (Soil Survey Staff 1975). Limnic soils are usually the result of organic material deposition and often found in lakes such as the thaw lakes of the Arctic Coastal Plain. Because of the unique properties and common occurrence of limnic soils in the Arctic, Soil Taxonomy needs to be amended to include limnic material as a subgroup of the Gelisol soil order.