Abstract:

The climate and ancient human activities changed with the Yangshao village soil over time. Although most of the changes disappeared from a macro perspective, they were preserved in the soil micromorphology. Therefore, this study adopted the soil micromorphology method to conduct multi-point sampling in a cultural layer of the Yangshao village site. By comparing the differences in the soil micromorphology characteristics of ancient soil, cultural layer, and topsoil, this study investigated the impact of climate change and ancient human activities on soil micromorphology, providing a basis for exploring relics of ancient human activity and agricultural development during the Yangshao culture period. First, the results showed that the soil experienced a strong degree of chemical weathering. At the same time, sedimentation and viscosity were obvious, and the clay gel film was fully developed. As the iron element was added and oxidized, the color became reddish-brown. The gel film moved downward or measured seepage with the soil solution and then lost water and deposits in the aggregate or pore wall, with a smooth and bright surface or waxy luster. Second, coarse grains in the cultural layer were mostly decomposed into small grains, accumulated with fine grains present at multiple b-junctions, and the spatial relationship between fine and coarse grains was also diversified. Humus was attached to the pore wall, and carbon chips filled the pore channel. Traces of fire could be clearly identified, and the red burnt soil presented a variety of shapes, mainly blocky and clastic. Traces of water could be clearly identified, showing either a directional arrangement or accumulation state. The water movement intensity could be further identified according to the size of the arranged particles. Earthing activities, such as smooth holes and scratches, could be clearly identified. Third, large coarse bone particles in the topsoil layer were scattered in the soil matrix, and the carbonate and clay gel films were mixed with irregular and unstable shapes, indicating weak pedogenesis and a short duration. Soil formation is mainly inherited from calcareous formation and calcareous neogenesis, and it can also be used to identify sediment clay. The soil stratification was single, and the pores showed an accumulative, irregular, and unstable state. In conclusion, the ancient soil layer was primarily affected by a warm and humid climate, with obvious desilication, iron enrichment, and aluminization, and the secondary minerals were primarily hematite. Ancient humans began to live here, promoting soil development. Sedimentation and viscosity were obvious, and the clay film was fully developed. Moreover, the cultural layer was mainly affected by ancient human activities. The intensity of ancient human activities was enhanced, and soil formations and horsts were diversified, clearly indicating the horsts were formed by ancient human activity. The soil microstructure appeared spongy, indicating that the cultivation maturity was high and the soil fertility reached a certain level. Furthermore, the topsoil layer was foremost affected by dry and cold climates, and the secondary mineral was primarily carbonate. The activity intensity of ancient humans weakened, and soil development slowed down. Large coarse bone particles were scattered in the soil matrix, and carbonate was mixed with the clay film.

Key words: Yangshao village site, soil micromorphology, soil accretion, soil formation