Correlation of the river valleys terraces of the Volhynian Upland based on morphological and lithological features

River valleys of Volhynian Upland are characterized by a larger number of terraces and a greater depth of their downcutting compared with neighbouring Polissia and Male Polissia. We established that the major rivers of Volhynian Upland have floodplain and mostly three terraces. The valley of the Horyn River is different from others by presence of fourth terrace. According to received information, the age of forming of the highest terrace (revealed only in the Horyn Valley) can be considered as Early Pleistocene, the third terrace – Middle Pleistocene, and the two lowest terraces – Late Pleistocene. Relief of the Early and Middle Pleistocene terraces is characterized by high degree of dissection and presence of sufficiently thick loess cover. At higher Late Pleistocene terrace loess cover isn’t revealed everywhere and has a small thickness (typically up to 5 m). The lowest terrace in most valleys has local distribution and it is composed mainly of sandy material. The surface of this terrace is located on several hypsometric levels. Floodplain usually has two high-rise levels. It formed in the Holocene. Key words: river valley, terrace, floodplain, Volhynian Upland, Horyn River, Styr River, Zakhidnyi Buh River.