Discovering the "Giants' Potholes": A new geotrail in the Apuan Alps UNESCO Global Geopark

With the exception of the Fatonero and Anguillaja streams on the southern slope of Mt. Sumbra, the strange landforms which are deeply carved into the carbonate rocks and named "giants' potholes", are not very widespread in the watercourses of the Apuan Alps. This central area of the Geopark shows a remarkable concentration of large potholes. For a long time, the Fatonero and Anguillaja streams were a frequent destination for hikers and climbers, thanks to the easy access and aesthetic appeal of the potholes in an outstanding scenic landscape. These morpho-sculptures have been classified as a major geosite in the Geopark's inventory due to their rarity, regular shape and size. Their geological importance has even been recognized by their inclusion in the "Italian Geosites Inventory" managed by ISPRA (i.e. National Geological Survey). The "giants' potholes" are of significant educational value with respect to fluvial processes involving plucking, abrasion and hydraulic erosion. In 2015, the Apuan Alps Geopark developed a short trail leading to the potholes of the Anguillaja stream in order to make these landforms more accessible and understandable to tourists. The comprehensive signposting of the trail involved the installation of informative, bilingual (Italian, English) panels. The explanations, which are addressed mainly to visitors without any previous geological knowledge, also deal with the history of geological research and quarrying activity in this area. The first panel is dedicated to Antonio Stoppani - a famous Italian geologist - who in 1872 understood and described the phenomenon of the subterranean water flow by studying the Tùrrite Secca, a karst stream which can be observed at the first stop near the beginning of the geotrail. The second stop along the footpath reveals an abandoned quarry that was cut into the marble along the stream bed during the 1970's, destroying some huge potholes in the process. Here a panel aims to emphasize the result of the irresponsible quarrying activities that are now prohibited thanks to the environmental restrictions introduced by the Geopark. At the end of the geotrail, a panel provides a description of the potholes and the geological interpretation of how these charming landforms were carved into the marble which forms the beds of the Fatonero and Anguillaja streams. Since the southern side of Mt. Sumbra is characterized by widespread glacial landforms produced by glaciers during the last Ice Age, erosion by pressurized meltwater flowing in subglacial channels could have fostered the formation of the potholes. The new geotrail is a powerful tool for disseminating geological information along an easy footpath that will provide hikers with direct contact with the natural environment. At the same time it will also improve the awareness of the Apuan Alps UNESCO Global Geopark's inhabitants about the need to protect the outstanding geological heritage of their territory whilst enhancing access to it.