Geoarchaeological and historical implications of late Holocene landscape development in the Carseolani Mountains, central Apennines, Italy

This study investigates the relationship between late Holocene landscape development and early human interaction by means of geomorphological and sedimentological analyses supported by GIS modeling operations. The selected geoarchives are sedimentary valley fills of two subwatersheds located in the upper Turano River drainage basin (60 km northeast of Rome, Italy), where humans settled at least since the earliest classic period. First the alluvial plains were identified and mapped through multiple GIS operations. Thereafter, 12 cores were taken from the alluvial plains, collecting in total 68 m of alluvial profiles. By sedimentological analyses (i.e., grain size, carbon determination) together with 36 AMS-radiocarbon dates, we identified phases when changes in the geomorphological evolution of the study area occurred. Starting around 4200 cal BP, eight distinct clusters of increased cumulated probability density functions of the C-14 dates were observed, representing enhanced alluvial deposition and/or fluvial activity. The shift from a phase of prevailing biostasy to a period of anthropic rhexistasy occurred after 4200 cal BP in the Rio di Riccetto and around 2200 cal BP in the more remote Ovito watersheds. Dividing the alluvial sediment volumes by the potential erosion areas and assuming a sediment delivery ratio (SDR) between 0.21 and 0.46, we obtained an average late Holocene surface lowering of 370 to 540 mm in the Rio di Riccetto and 400 to 510 mm in the Ovito watersheds. Our results show that notable land reshaping occurred in the vicinity of the city of Rome, which can be attributed to human-induced land cover changes. (C) 2014 Elsevier B.V. All rights reserved.