Geomorphological map and raised-relief model of the Carrara marble basins, Tuscany, Italy

Marble extraction in the Carrara basins has occurred since the 1st millennium BC, with relevant exploitation periods during the Roman period and the Renaissance, when Michelangelo visited the Carrara quarries to personally select the marble blocks he used for sculpting his legendary works of art. As a consequence of this long-lasting activity, the landscape is almost completely notched by extensive quarry fronts and covered by huge quarry dump deposits, locally named ravaneti. Through a detailed field survey and the interpretation of aerial photographs, we compiled a geomorphological map at a scale of 1:10,000 of the Carrara marble basins. Additionally, a raised-relief model at a scale of 1:10,000 was derived from the geomorphological map. To our knowledge, this model is the first product of this kind. A geomorphologic survey, historical documents, and stratigraphic and grain-size analyses allowed us to reconstruct the evolution of the anthropogenic landscape and allowed for the characterization of past and current geomorphic processes. Four main stratigraphic units are recognizable in the ravaneti. The different textures and structures of these units reflect the evolution of marble quarrying techniques. The oldest and deepest debris layer dates back to pre-Roman and Roman periods and is made up of flat pebbles with an open-work structure. In several localities, this manually produced debris is associated with very distinctive excavation cutting traces (caesurae in Latin), covering paleosoils predating the Roman excavation activity. Medieval and Renaissance ravaneti are locally documented on top of this unit, burying post-Roman soil. Coarse multi-decimeter-sized cobbles («head man» size cobbles) with a scarce fine matrix constitute the typical ravaneto of the end of 19th century. The uppermost layer, with boulders and an abundant fine matrix (ranging from sand to silt), is the consequence of the new diamond wire cutting methods that were introduced in the 1970s. The fine matrix produced by the recent techniques of block cutting and grinding destabilizes the dump deposits, making them very prone to hazardous remobilization of debris flows and shallow landslides. These are the most significant geomorphologic processes acting in this anthropogenic landscape. In general, the geomorphological map of this extractive environment offered the opportunity i) to verify that anthropogenic landforms archived the principal steps of technological development of such industrial context strictly linked to important cultural events, and ii) to evaluate what are the technological developments in excavation activities that could generate situations of geomorphological risk.