The study area is located in the central part of the forest-steppe zone of European Russia, in the vicinity of Zadonsk, Lipetsk region.
It is a highly dissected hilly terrain at an elevation on 170-180 m a.s.l. Quaternary sediments are represented by glacial deposits - moraine with a predominance of loam sediments with gravel, pebbles and clay (Geological map of quaternary deposits of the Lipetsk region, 1998). The upper sediments are presented by a thick layer of loess (up to 26 m), either calcareous or non-calcareous, sometimes with gypsum (Sycheva, et. al, 2017, Tregub, 2014).
The main rivers are the Don River and its tributary the Snova river. The study area is characterized by the temperate continental climate, with mean temperature 23,5°C in July and -9,5°C in January, and mean annual precipitation of 548 mm (https://en.tutiempo.net/). Natural vegetation is variable because the territory is located in the forest-steppe ecotone and consist of mixed-grass steppe and linden and oak forest patches (Atlas of the Lipetsk region, 1994.). The soil cover is dominated by Luvic Phaeozems (IUSS Working Group WRB, 2015) that cover uplands and gentle slopes. The vegetation is represented mostly by herbaceous-grassy communities with some patches of deciduous forest. Soils were formed on calcareous loess with single gypsum crystals.
The settlement represented hillforts of the Early Iron Age surrounded by defensive ramparts - an earth walls constructed from the soil excavated nearby. Two earth walls of Degtevoe settlement were built ~2500 (Db-1) and 2300 yrs BP (Db-2) by Scythian-like peoples. Scythian-like culture belongs to Scythian people who lived in the forest-steppe part of a Don region, rites of which were slightly different from Scythian culture (Medvedev, 1999).
Soils of the Degtevoe site were formed in calcareous loess with the inclusion of single gypsum crystals. The soils buried 2500 yrs BP (Db-1) and 2300 yrs BP (Db-2) are Greyzemic Stagnic Luvic Phaeozems (Gypsic, Cutanic, Loamic). The thickness of the rampart is 60 cm in the Db-1 soil and 30 cm in the Db-2 soil. The profile of the soil buried 2500 yrs BP includes AhEb-AhBtb-Btgyb-BCkgyb horizons. The colour of the upper horizon is 10 YR 3/2 (very dark greyish brown), in the lower part of the Ahb horizon, uncoated quartz grains were observed. The structure of the Ahb horizon is granular changing into prismatic and angular blocky in the underlying AhBtb horizon. A lot of Fe and Mn hard concentrations were revealed in the Btgyb horizon indicating redox conditions. The clay cutans covering ped faces are also common in this horizon. Single gypsum crystals occur from 40 cm toward the parent material. In the BCkgyb horizon, the clay cutans get darker in colour and Fe-Mn concentrations become more abundant. Сarbonates occur from 105 cm and are presented as soft nodules whose size reach 5 cm.
The buried 2300 yrs BP soil consists of AhEb-AhBtb-Btgyb-Bgyb-BCkb horizons. AhEb horizon consists of lighter and darker (10 YR 5/2) parts. The clay-humus cutans appear in the underlying AhBtb horizon. The Fe-Mn concretions are present in all subsoil horizons. Single gypsum crystals (up to 3 mm) appear in the Btgyb horizon. Rare soft carbonate nodules appear at a depth of 130 cm in BCkb horizon.
The surface soil (Ds) is classified as Greyzemic Stagnic Luvic Phaeozem (Anthric, Cutanic, Gypsic, Loamic) and consist of the following horizons: Ahp-Ahpy-Bty-Btgy (Fig. 4, 11). The Ahp horizon is characterised by the greyish brown colour 10 YR 5/2 and weak granular structure (Table 2). Beginning with Ahpy horizon single gypsum crystals occurs. The Ahpy horizon consists of unstructured and very dense material because of ploughing. The subsoil is also dense, characterised by an angular blocky structure with clay and humus cutans on the ped faces. The Btgy horizon contains Fe-Mn concentrations, with the depth their amount decreases.
Soils of Degtevoye site contains a small number of carbonates, the high values of CaCO3 found in BCkgyb horizon of the Db-1 soil (1,4%), other soils either do not contain them at all or contain only 0,1% (Bty, Btgy horizons in Ds soil, Btgyb, Bgyb and BCkb). Abundant soft carbonate concretions in the soils of the Degtevoye site can be identified from 105 cm in Db-1 soil, while rare carbonate neoformations starts from 130 cm in Db-2 soil. As well as carbonates, single gypsum crystals found 30 cm lower in Db-2 soil in comparison with Db-1 soil. Dissolution and further migration of gypsum and on 30 cm point to increased humidity existing 2300 yrs BP. The groundmass in the Btgyb and BCkgyb of the soil buried 2500 years BP is characterised by a high level of birefringence and random striated b-fabric. In the soil buried 2300 years ago, reorganization of fine material leads to the low-level birefringence of the groundmass and granostriated b-fabric. In the Db-1 soil, most of the clay coatings are presented as assimilated fragments , while in the Db-2 soil clay coatings uniformly cover structural ped surfaces. The distribution of the plant communities displays higher proportions of forest and meadow grasses and two times lower proportion of the steppe grasses in the Db-2 soil compared to the soil buried 200 years earlier. The high amount of Fe-Mn concretions in were noted in soils of this site, but in Db-2 soil amount of concretions are higher.
We conduct, that transformations of the soil buried 2300 yrs BP were caused by climatic fluctuations in the direction of increasing humidity. This conclusion is confirmed by the phytolith spectrum, the proportion of steppe communities halved in comparison with the Db-1 soil and share of forest and meadow grasses increase in this soil.
- Kurbanova, Fatima; Makeev, Alexander; Puzanova, Tatiana; Kust, Pavel; Chernov, Timofey. Soil indicators of Late Holocene forest-steppe landscape evolution on the Russian Plain International Multidisciplinary Scientific GeoConference : SGEM Sofia, Том 18, Изд. 3.2, (2018). DOI:10.5593/sgem2018/3.2/S13.064
- Puzanova, Tatiana; Makeev, Alexander; Khokhlova, Olga; Aseeva, Elena; Kurbanova, Fatima. Holocene signals of climate dynamics in the profiles of soils buried under archaeological objects in the central part of the East European Plain International Multidisciplinary Scientific GeoConference : SGEM; Sofia, Том 17, (2017). DOI:10.5593/sgem2017/32