Cryogenic soils near Batagay megaslump, located in the Verkhoyansk region, northern Yakutia were investigated in detail in August-September 2019. Soil samples from the Batagay megaslump were analyzed for organic carbon and humic substances. The pH was determined in soil extracts. On the slope to the Batagay megaslump, a soil catena was studied. It included the near-summit surface of the Kirgilyakh slope, the middle part of the slope, as well as the bord of the Batagai megaslump. The soil cover in the area of the Batagay ravine is represented by various types of soils formed on permafrost rocks, mainly Cryosols Gleyic, found in various landscape conditions, and Podzols Entic are also sporadically distributed in the area. On alluvial deposits in the valley of the Batagaika river Podzols Haplic are formed. Leptosols Lithic are confined to the elevation of the relief with bedrock located close to the surface. The main processes typical for soils in the Batagay megaslump area are: cryogenic structuring, organic matter accumulation, Al-Fe-humus and gleiing processes. Above the permafrost horizon a local minimum of pH values was noted both in Podsols Entic and in Cryosols Gleyic.

The content of organic carbon and humus in soil samples was carried out in the laboratory of the Ecological and Geochemical Center at the Faculty of Geography of Lomonosov Moscow State University under the leadership of E.V. Terskaya. The measurements were carried out according to the method of I.V. Tyurin, which is based on an oxidation of organic carbon in soils with an excess of Cr⁶⁺-ion.The hydrogen index (pH) was measured in 30 samples taken from the genetic horizons of soils near the Batagay megaslump in August 2019. Water extracts of soils were made by mixing pre-dried, pounded with a porcelain pestle in a porcelain mortar and sifted through a sieve (with a pore diameter of 1 mm) of a sample with distilled water. Mixing was carried out in a ratio of 1:25 for samples from peat horizons O and in a ratio of 1:5 for samples from all the other soil horizons.Soil horizons were named according to the nomenclature by Shishov et al. (2004):O: Organic horizon less than 10 cm thick comprises peat and detritus;pir: Any horizon that contains coal. Stands for “pyrogenic”;┴ : Any permafrost horizon;E: Stands for “eluvial”. Analogue of albic horizon. The albic horizon is defined as a diagnostic subsurface horizon that is comprised of primary sand and silt particles that are light-colored because they lack iron oxide coatings;BF: Illuvial horizon, that is enriched by iron oxydes;BHF: Illuvial horizon, that is enriched by iron oxydes and humus;f: Any horizon with distinct signs of iron accumulation;p: Rock inclusions;CRM: Stands for “cryo-metamorphic”. Mineral horizon with granular structure caused by cryogenic processes;C: Loose parent material