Pliocene Geotourism: innovative projects for the valorization of the paleontological heritage of three different-staged quarries of Tuscany (Central Italy)

Introduction Quarries are areas of crucial importance for geological and paleontological studies as they represent privileged windows on the geological history of an area. The geoscientific relevance of quarries can be even increased if they are employed for teaching activities and geotourism. Geotouristic activities are necessary, for instance, for abandoned quarries which are often considered as unevaluated and degraded areas. As regard paleontology, innumerable fossils have found in quarries all around the world. Some iconic examples include the German Jurassic quarries at Holzmaden and Solnhofen, featured by exquisitely preserved skeletons of ichthyosaurs and the "Urvogel", Archaeopteryx. The Italian peninsula is densely punctuated by quarries from which different types of stones and loose sediments are extracted for industrial purposes. Tuscany, in particular, hosts 384 active and almost 2000 inactive or abandoned quarries. Most of these quarries extract Pliocene sediments (sand and clay), and some of them have been the location of important fossil finds, including holotypes and first occurrences of taxa in the Mediterranean Basin. Unfortunately, these important fossils represent only a small part of the fossil assemblages contained in these sediments: in fact, many of them are lost during the quarrying activities. For preserving this legacy and encouraging geotouristic activities, a valorization plan has to be elaborated. With this goal in mind, we focus on three different-staged quarries of Tuscany where fossil vertebrate-bearing Pliocene deposits are exposed. For each of these sites, several suggestions for preservation and valorization are proposed, focusing on the importance of geotourism, and involving the broadest audience possible. Many innovative dissemination tools, such as 3D technologies, are now luckily available for implementing such a purpose. The quarries The investigated quarries are La Serra (active), Arcille (inactive), and Certaldo (completely abandoned) (Fig. 1). They are located in two different Neogene Basins: La Serra and Certaldo take their place in the Valdelsa Basin (central-western Tuscany), whereas Arcille is part of the Baccinello-Cinigiano Basin (central-southern Tuscany). The Valdelsa Basin extends for 60 × 25 km in Apenninic direction and is filled with Mio-Pleistocene deposits, whereas the Baccinello-Cinigiano Basin is smaller and preserve rocks spanning chronostratigraphically between the Miocene and the Pliocene. In order to suggest several outputs for the valorization and the recovery of Tuscan quarries, three of them (which are currently under study) were taken as examples, not only for their scientific importance, but also for their different employment condition. La Serra quarry is placed in the vicinities of San Miniato (Pisa Province). Here, four different continental and shallowmarine units, referred to the late Pliocene, are exposed. The site has been studied since 2012 and preserves many sedimentological and paleontological emergences along a ca- 25-m-thick stratigraphic succession. Here, besides wonderful examples of cross stratification and other sedimentary structures, many fossil vertebrate remains have been recorded. A huge amount of land mammal remains (preliminary referred to proboscideans, cervids and suids), freshwater and terrestrial turtles, and bony and cartilaginous fishes comes from these deposits. The marine fossil assemblage includes the great white shark (Carcharodon carcharias), stingrays and other sharks and rays (Garassino et al., 2012; Collareta et al., 2020a). Based on sedimentological and paleontological data, the paleoenvironment testified by the La Serra quarry is comprised of deltaic, lagoonal and shallow-marine settings. The studied succession exposed at Arcille quarry (Grosseto Province) is comprised of fluvial and marine siliciclastic deposits such as sandstones, conglomerates and shelf mudstones. Here, impressive sedimentary structures (cross stratifications and gutter casts) are recorded. Relevant fossil remains come from this site, including marine mammals, bony and cartilaginous fishes. Among these specimens, the holotype of the cetacean Casatia thermophila (Bianucci et al., 2019) and of the putative rajid Nebriimimus wardi have been recently described (Collareta et al., 2021). The fossil assemblage of the Arcille quarry also includes bivalves, gastropods, scaphopods, corals, barnacles, crabs, echinoids, and several fossil traces. The Arcille quarry provides an unparalleled reference for the early Pliocene paleoenvironmental reconstruction of the Tuscan coasts. Sedimentological evidence depicts a shallow-marine setting, close to a river estuary. The presence of the topping mudstones is linked to a shelfal depositional framework. The marine fossil assemblage, mostly comprised of coastal taxa, also includes many open-sea taxa, suggesting a spatial closeness between marginal and pelagic settings. The third site is located in the surroundings of Certaldo (Florence Province). It is comprised of an abandoned quarry, in which massive, grayish shelf mudstones are exposed. The succession crops out in a badland-like context. Here, elasmobranch teeth and bony fish otoliths have been recorded (Collareta et al., 2020b) and are currently under examination. In the vicinities of Certaldo, other fossiliferous sites are under investigation, where marine mammals as well as cartilaginous and bony fishes remains have been abundantly collected. The presence of mudstones in the quarry constitutes a strong evidence of a shelf depositional paleoenvironment. All these sites are of crucial importance for paleontological and geological investigations of the Tuscan Pliocene. The scientific relevance, geographic position, accessibility and new employment opportunities (especially for the last two quarries) allow for considering the quarries of La Serra, Arcille and Certaldo as geoattractors. Geotourism activities, teaching and popular science programs can be proposed in order to protect, promote and enhance their geopaleontological heritage. Geoheritage valorization Geotourism is an increasing phenomenon that promotes geosites and their scientific heritage. The three aforementioned quarries can be considered as suitable places to host visits, guided tours, fieldtrips and outdoor teaching activities. The use of 3D technologies and virtual reconstruction tools would also increase attractivity for a broad public outside academia. Several enhancement proposals are here provided for each of the aforementioned quarries. The present-day extracting activity at La Serra quarry may represent a potential danger for the preservation of geological structures as well as, perhaps more importantly, fossil specimens. An informal partnership with the quarry supervisor has been established, resulting in the precious opportunity of monitoring and check periodically the evolution of the quarry and its new discoveries. In this respect, the first proposal for the valorization of the geoheritage of this quarry is that of collecting multimedia material to create visual exhibitions in museums dealing with the relationship between anthropic activities and the environment. Furthermore, interactive 3D reconstructions of the quarry (Fig. 2) in different moments of the past could facilitate the dissemination of our geoconservation project. The relatively easy accessibility of the Arcille quarry allows for multiple geotouristic purposes. Teaching activities and guided fieldtrips, including school students as well as an adult public, may be implemented in this area. Interactive 3D models and Augmented Reality could be used directly by the visitor, even in the field, by projecting virtual reconstructions on the background of a real environment. Permanent installations (e.g. informative and didactic panels) can be placed in the site to disseminate information about the history of paleontological discoveries at this foremost geosite. Our plans for Certaldo are not limited to the quarry: we project to build up a “diffuse geosite” of the Certaldo area, including also other fossil-bearing locations in the vicinities of the abandoned pit. The latter would provide an available, somewhat “wild” background where a broad spectrum of restoration activities may take place. The final goal is the conversion of the quarry in an open-air virtual museum. Augmented reality and 3D technologies would be used to reconstruct and visualize the Pliocene marine environment of the area, and people would view everything via their own mobile device. Thus, Certaldo quarry (Fig. 3) can be the core of this new 2.0-museum, an interesting proposal for the requalification of an abandoned area. Concluding remarks Quarries are privileged windows for scientific studies. In the Italian peninsula, Tuscany hosts lots of active, inactive and abandoned quarries. We take in account three different-staged quarries (La Serra, Arcille and Certaldo), comprised of Pliocene deposits. These sites are deeply relevant for their geological and paleontological heritage. For all of them, revaluation programs are here suggested, in order to promote and valorize their geological and palaeontological legacy. Permanent exhibitions, teaching and dissemination activities, fieldtrips and geotourism are the base for the valorization of these geosites. In particular, I) La Serra quarry would be employed for monitoring and multimedia collections for the establishment of museum expositions; II) Arcille quarry would host permanent, informative installations, being also the location of didactic fieldtrips; furthermore, the use of 3D tools and augmented reality would increase the interest in the public; III) Certaldo quarry could become the center of a “diffuse geosite”, converting the area in an open-air virtual museum. Requalification programs are of crucial importance for cultivating the awareness of the outstanding geological and paleontological heritage of Tuscan Pliocene. References Bianucci G, Pesci F, Collareta A, Tinelli C (2019) A new Monodontidae (Cetacea, Delphinoidea) from the lower Pliocene of Italy supports a warm-water origin for narwhals and white whales. Journal of Vertebrate Paleontololgy, 39:e1645148 Collareta A, Merella M, Casati S, Di Cencio A (2020a) Did titanic stingrays wander the Pliocene Mediterranean Sea? 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