Natural and anthropogenic channel pattern changes in the mid-mountain valley during the Late Glacial and Holocene, Polish Uplands

The purposes of this study are to describe the channel patterns of the Czarna Nida River quantitatively and to determine the factors that have had the greatest influence on the development of these patterns. Among the factors considered were natural (climatic) and anthropogenic (prehistoric metallurgy). River development was examined with a focus on valley floor formations, channel geometry changes, and depositional changes. River widths and channel patterns were measured on aerial photographs, and longitudinal profiles were prepared from topographic maps. Within the bottom of the valley, in a single morphological level, a row of inserts of various ages appears. These inserts were formed by the river of different development of the channel – macromeanders (Late Glacial) – multichannel systems (Early Holocene, Subatlantic) – small meanders (Holocene). General tendencies of the Late Glacial and Holocene erosion–accumulation cycle are related to the well-known principles for valleys of Central Europe and described in numerous studies. They encompass dissection from the turn of the younger Pleniglacial and Late Glacial, Younger Dryas straightening and braiding of channels, as well as Holocene phases of intensified fluvial activity. In the Czarna Nida River valley, distinct traces of higher fluvial activity linked with development of prehistoric iron metallurgy in the Roman period were recognised.