Mem. Descr. Carta Geol. d’It. LXXXVII (2009), pp. 15-28 figg. 14 Geomorphology, environmental geology and natural-cultural heritage of Palmaria, Tino and Tinetto Islands (Portovenere Park, Italy) Geomorfologia, geologia ambientale e patrimonio naturale-culturale nelle Isole della Palmaria, del Tino e del Tinetto (Parco di Portovenere, Italia) BRANDOLINI P. (*), FACCINI F. (*), PICCAZZO M. (**), ROBBIANO A. (*) ABSTRACT – The islands of Palmaria, Tino and Tinetto re- RIASSUNTO – L’arcipelago delle isole Palmaria, Tino e Tinetto, present the western limit of the Gulf of La Spezia. They ubicato al limite occidentale del Golfo di La Spezia (Liguria constitute the seaward extension of the Portovenere Pro- orientale), costituisce la naturale prosecuzione del Promon- montory, part of the site inscribed on the UNESCO World torio di Portovenere e rappresenta un sito di grande interesse Heritage List. The three islands comprise a small archipe- geomorfologico-culturale, con importanti aspetti scientifici, lago, which has been protected since 2001 as part of the Na- paesaggistici, socio-economici e storici, in particolar modo tural Park of Portovenere. Geomorphological features and legati alla plurisecolare attività estrattiva, anche in sotterra- numerous traces of the historic quarrying of the precious neo, del pregiato marmo Portoro. Portoro marble characterize the islands. The geology is mar- Dal 1997 l’arcipelago è stato riconosciuto come Patri- ked by an overturned fold, with overlapping dolomitic lime- monio Mondiale dell’Umanità dall’Unesco e dal 2001 è tute- stone rock strata, affected by karstic phenomena that are also lato dal Parco Naturale Regionale di Portovenere. of archaeological importance. The geomorphological mo- L’assetto geologico-strutturale è caratterizzato da una deling is conditioned by the structural arrangement and the piega anticlinale rovesciata con asse NW-SE nella quale si ri- tectonic lineations: the processes in progress are mainly re- scontra la sovrapposizione di strati calcareo-dolomitici, in- lated to wave undercutting, which determines a cliffed coa- teressati da diffusi fenomeni carsici. Tra Palmaria, Tino e stal profile on the slopes facing SW and SE, while the other Tinetto sono infatti censite una trentina di cavità naturali, al- island sectors present coves with pocket beaches. The islands cune delle quali di importanza anche archeologica, come la of Palmaria and Tino are well known for the extraction of Grotta dei Colombi. Portoro marble during the Roman period. Portoro, quarried Il profilo costiero delle isole è condizionato dall’assetto mostly underground, is a black marble with gold, white and tettonico ed in particolare le falesie che caratterizzano i set- rose-colored veining, utilized as ornamental stone. The is- tori sud-occidentali delle isole della Palmaria e del Tino sono lands are basically visited for hiking excursions and beach impostate lungo una faglia diretta orientata NW-SE. I ver- outings, and the environmental heritage they represent is of santi nord-orientali degradano a mare con pendenze relati- great value for tourism. Initiatives aimed at the valorization vamente più modeste e si presentano bordati da piccole and protection of this heritage are needed. Based on the geo- spiagge ghiaioso-ciottolose. logical and geomorphological aspects, geotourist map of the Tracce di modellamento dei versanti dovuto a processi Palmaria islands was prepared to promote an understanding gravitativi sono presenti soprattutto sulle pendici sud-occi- of the landscape and to valorize the environmental values. dentali dell’Isola della Palmaria, dove si osservano falde de- tritiche, talora frammiste a depositi colluviali. In alcuni casi KEY WORDS: Geomorphology, Environmental geology, Cul- questi depositi sono debolmente cementati e rappresentano tural heritage, Palmaria Island, Ligurian sea. un’interessante testimonianza di variazioni climatiche del passato. (*) Dipartimento di Scienze dell’Antichità, del Medioevo e Geografico-ambientali, University of Genoa, Italy (**) Dipartimento per lo Studio del Territorio e delle sue Risorse, University of Genoa, Italy [email protected] 16 BRANDOLINI P. - FACCINI F. - PICCAZZO M. - ROBBIANO A. Sulla base degli aspetti geologici, geomorfologici e geo- mental education), Forte Cavour and Forte Umberto I. ambientali rilevati, è stata preparata dapprima una carta geo- The islands also took on social and economic morfologica-ambientale e successivamente una carta geoescursionistica dell’Isola della Palmaria, con lo scopo di importance, owing to their geomine features: ex- favorire la comprensione del paesaggio e la sua valorizza- traction of the precious Portoro marble has been zione estendendone la fruizione a diverse tipologie di escur- traced back to the Roman period, and continued sionismo: didattico, scientifico, sportivo e turistico-culturale. on through to the end of the 20th century. Lungo la rete escursionistica sull’Isola della Palmaria (sul For these reasons, there has been recent growing Tino la visita è ad oggi interdetta per attività militari) sono stati evidenziati i principali geositi, con particolare riferi- interest in educational and recreational activities mento a quelli connessi alla geomorfologia culturale. I sen- made possible through and linked to the develop- tieri, suddivisi secondo una scala semplificata di difficoltà, ment of geomorphological and geomine trails sono stati esaminati in rapporto ai pericoli naturali che pos- (BRANDOLINI et alii, 2005; ROBBIANO et alii, 2005). sono coinvolgere l’escursionista, spesso associati a particolari The islands of Palmaria, Tino and Tinetto have condizioni meteorologiche, ed agli elementi di vulnerabilità legati alle loro caratteristiche strutturali (esposizione, lar- been protected by the Cinque Terre network of pro- ghezza, tipo di fondo). tected areas in the Liguria Region since 1985 Per la fruizione degli aspetti geomorfologico-culturali si (BRANDOLINI & ROLLANDO, 1995). As of 2001, propone la realizzazione di alcuni itinerari guidati: nell’Isola they have represented part of the Regional Natu- della Palmaria si può distinguere un percorso legato all’im- ral Park of Portovenere, and in 1997, the archipel- piego dei materiali lapidei nell’architettura civile e militare ed uno storico-geominerario. Le peculiarità geomorfologiche ago was recognized as a World Heritage Site by delle isole, con particolare riferimento ai processi legati al UNESCO. These places have fascinated Romantic modellamento costiero, possono essere infine pienamente and contemporary poets and have served as inspi- apprezzate attraverso un percorso a mare. ration for literary works, musical compositions and paintings. In fact, the area is of exceptional value, PAROLE CHIAVE: Geomorfologia, Geologia ambientale, Pa- trimonio culturale, Isola Palmaria, Mar Ligure. one that reveals the relationship between hu- mankind and nature, the source of a landscape of extraordinary scenic beauty. The objective of this work is to broaden the 1. – INTRODUCTION knowledge of the geology and geomorphology of the area as cultural elements of the landscape, as The archipelago of the islands of Palmaria, well as their interaction with the presence and ac- Tino and Tinetto (Ligurian Sea) represents a site tivities of humans, with the aim of valorizing the of exceptional geomorphological and cultural area culturally and in terms of tourism. value. The site’s important scientific, scenic, so- Additionally, existing geomorphological haz- cioeconomic and historical features offer an op- ards that could affect the numerous visitors along portunity to broaden our understanding of the hiking trails in Palmaria Island, were also taken geomorphological and geoenvironmental issues into consideration, with the objective of guaran- (BENNETT & DOYLE, 1997; PANIZZA & PIACENTE, teeing sustainable tourism and helping tourists be- 2003; GRAY, 2004). come informed and aware; Tino and Tinetto The islands are characterized by a high rocky islands were not examined because they are mili- cliff on the western and southern slope, whereas tary zone. the remaining coastline is more jagged, with small promontories and pocket beaches. There are many cave openings, including both karstic and sea 2. – GEOGRAPHIC FRAMEWORK caves, in the limestone and dolomite, which con- stitute the bedrock of the three islands. Some of The islands of Palmaria, Tino and Tinetto are these caves, such as the Grotta dei Colombi, have located along the western limit of the Gulf of La been object of research in the past and are of Spezia in eastern Liguria (fig. 1). They constitute great importance not only in terms of their his- the natural extension of the Portovenere Promon- torical and archeological value, but also in terms tory (fig. 2). In fact, the islands present an approx- of their scientific value, as they contain valuable imately NW-SE alignment and the possibility that evidence of past climatic variations (CIGNA, 1967). at least Tino and Tinetto were once joined cannot Settlements on the islands date back to prehistoric be excluded (CIGNA, 1967). times. The islands were the seats of important The island of Palmaria, Liguria’s largest island monastic communities in the Middle Ages, and of with a land area of 1,65 km2, has an approximately military defense and naval bases starting from the triangular shape with three sides that are about 3 end of the 19th century, when major defense km in length. The maximum elevation (about 190 works were built, including the Punta della