Dynamic evolution of badlands in the Roglio basin (Tuscany, Italy)

The Roglio basin, in the relatively arid Central Tuscany (Italy), is characterised by the presence of 191 badlands that have developed on Pliocene fine-grained blue clays. A morphometric analysis on the badlands has highlighted that these landforms formation and distribution are primarily related to the steepness of the hill flanks, which favour runoff and gravitational processes, along with favourable aspects, typically the southern ones that experience a stronger solar-induced daily thermal variation. A detailed physico–chemical analysis of the clayey material involved has also been carried out, with the specific aim of testing whether this plays a role in the various stages of activity shown by the Roglio basin badlands. The results indicate that there are no significant differences in the physico–chemical properties of an active vs. an inactive/dormant badland. Observation and field data, however, indicate that the dynamic of the Roglio basin badlands is strongly controlled by the occurrence of earth flows and the velocity of sediment removal at the bottom of the badlands. These two processes, variously combined at different intensity in relationship to many local factors, are likely to be the main responsible for the different stages of activity shown by the Roglio basin badlands.

Research Highlights► The location of 191 badlands in clayey terrains of Central Tuscany (Italy) appears largely controlled by the steepness of the hill flanks and a southern aspect. ► A high slope favours runoff and gravitational processes, while a southern aspect determines stronger daily thermal variation. ► Different stages of badland evolution (from totally inactive to totally active) are independent to various physico-chemical properties of the clayey terrains. ► The dynamic of the badlands appears to be strongly controlled by the frequency of earth flows events and the velocity of sediment removal from the system.