Small catchments evolution on clayey hilly landscapes in Central Apennines and northern Sicily (Italy) since the Late Pleistocene

The study aims to define a possible evolutionary geomorphological model of small catchments (i.e., <40 km2) that characterise the clayey hilly landscape of Central Apennines and Northern Sicily piedmont for the late Pleistocene–Holocene (i.e., the last 20,000 years, from the last glacial stage to the Holocene climate amelioration). The study is based on an integrated approach incorporating (i) geomorphological surveys and mapping, (ii) dating of Quaternary continental deposits, and (iii) topographical and morphometrical processing. It combines the data collected from previous published investigations as well as new data, specifically related to the availability of geo-chronological markers, and helps outline a common evolutionary model. The selected small catchments are tributaries of major rivers in inland areas (small catchments of the inland hills of Tuscany, Marche, and Sicily) or flow directly to the coast (coastal small catchments in Abruzzo). For each area, the geomorphological features (clay dominated bedrock, erosional landforms and fluvial terraces, and erosional/depositional strath terraces) and the dating of Quaternary deposits (from <50kyr to 15kyr) were compared, reconstructing the morphometry of the probable late Pleistocene landscape configuration. The analysis of the results showed that, although currently characterised by different climatic and geo-structural conditions, the different basins underwent a common geomorphological evolution mostly since the late Pleistocene. During the last glacial stage, under cold climate rhexistasy conditions, the small catchments were dominated by low gradient erosional surfaces with the deposition of fluvial, colluvial, or slope deposits, resulting in the formation of uniform slopes and wide minor valleys. The Holocene climate warming, together with marine transgression and tectonic uplift, induced the incision and dissection of the erosional surfaces and the continental deposits via gravitational movements and rapid erosion processes up until the present-day landscape configuration. The control factors of this evolution are most likely linked to the climate changes at the beginning of the Holocene and the interplay with the changes in the local base level of the small catchments since the late Pleistocene, combining late Quaternary tectonic uplift, sea-level rise, and river/coastal incision.