Stratigraphy of Peat Bog in the Gorobets River Valleyand Development of Natural Environments of Shikotan Island (Lesser Kurile Ridge) in the Holocene

摘要

The stratigraphic subdivision of peat in the Gorobets River valley, the largest river on ShikotanIsland, is conducted based on the study of palynological and diatom assemblages, tephrostratigraphy, and radio-carbon dating. The study object is one of the oldest peats in the South Kurile region and reflects the developmentof natural environments beginning from the early Holocene. Nine phases are distinguished in the developmentof vegetation on Shikotan Island. The changes in vegetable communities were determined by climatic fluctua-tions during the Holocene. Their ages, the factors responsible for the appearance and extinction of particularconiferous, small-, and broad-leaved taxa, and changes in their landscape-forming role during different periodsof the Holocene, as well as specific features in the formation of the present-day vegetation on the Lesser KurileRidge representing a separate floral area, are established. In addition to the climatic and sea-level fluctuations,the development of the island landscapes was determined to a significant extent by its topography, size, and iso-lation.