Inventory and analysis of geological and topographic distribution of “Balze” crags in the Upper Valdarno basin (Tuscany region, Italy)

Abstract

In this work we provide an analysis and an updated inventory map of the main outcropping crags, known as Balze in Italy, in the Upper Valdarno basin (Tuscany, Italy). These erosional forms develop in the alluvial-fan deposits that characterize this area. The study area extends up to 30 km2 within the local ANPIL (Natural Protected Area of Local Interest) and can be ascribed as a geomorphosite. Detection and mapping of Balze exposures were outlined on a pre-existing broad raster database, and then improved by means of photo-interpretation of optical imagery and analysis of Digital Terrain Model (DTM) and of topographic layers at 1:2,000 and 1:10,000 scale, supported by field work. A total of 151 Balze exposures were mapped and classified according to their progressive erosional stages, i.e.linear or indented escarpments, spire rocks and pinnacles or residual pillars. Furthermore, the spatial distribution of Balze scarps was investigated with respect to the geological and geomorphological setting and to the landscape zonation of the study area. Results of the inventory and analysis of geological and topographic distribution of the Balze crags can be useful for the characterization of the geomorphosite in the framework of its activity and management.