*Article* **Preservation of the Geoheritage and Mining Heritage of Serifos Island, Greece: Geotourism Perspectives in a Potential New Global Unesco Geopark**

**Nikolaos Vlachopoulos \* and Panagiotis Voudouris \***

Faculty of Geology and Geoenvironment, National and Kapodistrian University of Athens, 15784 Athens, Greece **\*** Correspondence: nvlahopoulos@gmail.com (N.V.); voudouris@geol.uoa.gr (P.V.)

**Abstract:** Serifos island is characterized by rich geodiversity, industrial and cultural heritage. The present paper focuses on the geological and mining heritage of Serifos, with the aim of integrating the island in the international environment of Geoparks, in the near future. In this geopark, Serifos can highlight the rich geological heritage of the island combined with the rich industrial heritage as expressed by mining activities since prehistoric times and the mining facilities of iron and copper mines. During the present study, six geotrails have been developed to link these cultural and ecological sites with the geological heritage. Along the routes, the geodiversity is explained, including its relationship with the surrounding biodiversity, and the historical and cultural aspects of the region. In the proposed geocultural routes (geotrails), the dialectic relationship between Humans and Nature is determined by historical conditions and by the record of the process that transforms space into a landscape. The geological-mining heritage of Serifos will attract people from all over the world with different kind of interests and will make it known to alternative tourists. The results of this paper are intended to constitute a valuable tool for enhancing and raising awareness of the geological heritage of the island of Serifos.

**Keywords:** geosite; geotourism; mineralogical heritage; geo-conservation; mineralogical museum; iron mines; skarn-related mineralization; geotrails

#### **1. Introduction**

Geoheritage comprises those elements of the Earth's geodiversity (rocks, minerals, fossils, landforms, sediments, water and soils) that are considered to have significant scientific, educational, cultural or aesthetic value [1,2]. Traditionally, the valorization and the use of geological valuable areas as touristic resources has been linked to areas characterized by the beauty of the landscape, the spectacular rock formations or relevant features (mountains, glacier formations, rivers, canyons, caves, etc.) interesting for people loving geology or, at least, nature [1–4]. As stated by Carcavilla et al. [4] "Geological-geomorphological heritage is the collection of geotopes, deposits, forms, and processes that comprise the geological history of each region, and the concept of preserving geological-geomorphological heritage is a cultural concept". Geoheritage aims to highlight the diversity of our planet to illustrate the importance of the biotic and abiotic factors, which document the historical evolution of the Earth [5]. The value of geological heritage is further underlined in a report from UN-ESCO [6], according to which geological heritage is characterized as the whole of the most interesting geological sites (geotopes, geoparks, and geological natural monuments) that deserve to be preserved for scientific, didactic, historical, aesthetic, and cultural reasons.

In addition to geoheritage, the industrial and mining heritage means all the sources of the industrial past that contribute to the knowledge of the history of the productive activities of a country or a population. Considering a monument or an object of industrial use as an information carrier is important and necessary since it incorporates all the influences of culture and the environment.

**Citation:** Vlachopoulos, N.; Voudouris, P. Preservation of the Geoheritage and Mining Heritage of Serifos Island, Greece: Geotourism Perspectives in a Potential New Global Unesco Geopark. *Geosciences* **2022**, *12*, 127. https://doi.org/ 10.3390/geosciences12030127

Academic Editors: Piotr Migo ´n, Karoly Nemeth and Jesus Martinez-Frias

Received: 13 February 2022 Accepted: 9 March 2022 Published: 10 March 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

Geotourism is connecting the geological heritage with the natural environment and the cultural monuments [7–10]. Geoheritage is the driving force of the geotourism itineraries and cultural heritage is also added to increase the value of the visited regions. The management of industrial and geological heritage has demonstrated a number of special applications, such as geoparks, technology parks, eco-museums or theme parks, cultural centers, recreation sites and industrial museums in order to emerge as tourist destinations.

At present, there are 169 UNESCO Global Geoparks in 44 countries, six among them in Greece [11] (Figure 1). Geoparks are wider areas that contain significant sites of geological monuments and geotopes as well as sites of ecological, archaeological, historical or cultural interest and are tools for environmental education [6,12,13]. The concept of geopark was attributed to areas with special geological appearances, which can contribute to sustainable local development. Thus, the establishment of a geopark not only opens up new opportunities and creates enthusiasm for geoconservation, but the park also becomes a new tourist attraction.

Serifos island, located in the South Aegean Sea, represents a multiple-mineralized district, including porphyry, skarn, carbonate-replacement and vein-type ores [14–18]. The Serifos mineralization is related with the emplacement of I-type granodiorite, considered to be synchronous with Miocene extensional detachment faulting, and intruded gneisses, amphibolites, schists and marbles causing an extensive contact metamorphic aureole [14,15,19–23].

Serifos is well known to collectors for its spectacular skarn-related mineralization with gem quality green quartz crystals with actinolite inclusions (prase or prasem) [24–30]. The Serifos minerals are among the most impressive collectable objects exhibited in museums and private collections worldwide. These minerals at Serifos can be founds either on the surface, but also underground in mining sites and include species of exceptional beauty and scientific value [28].

The Serifos island is also known for its numerous iron mines opened in: (i) numerous magnetite-rich skarns; (ii) hematite/limonite ± barite ore bodies hosted in marbles that were exploited until 1963 [15,31]. Already Ducoux et al. [15] emphasized the role of lowangle detachment fault systems to ore mineralization at the various mining sites, and described the geological and mineralogical characteristics of Serifos. From an archeological point of view, Serifos island is famous for the exploitation of copper ore during ancient times [32,33].

The aim of this article is to summarize the current state of knowledge on the geology, petrology, mineralization, and the primary mineralogy and mining characteristics of Serifos island, and to expand on previous work by highlighting its unique geological, petrological, mineralogical, mining, and educational features. We suggest various geosites and industrial sites on the island, present new geotrails that could be used for geotourism, cultural, education and research activities, and evaluate all data considering Serifos as a best candidate for integration in a potential new Unesco Global Geopark.

**Figure 1.** Geological map of (**a**) Greece and (**b**) Attic-Cycladic Crystalline Belt, showing the major tectonic structures, as for example, the North Cycladic Detachment System (NCDS), the West Cycladic Detachment System (WCDS). The location of Lesvos, Psiloritis, Chelmos-Vouraikos, Vikos-Aoos, Sitia and Grevena-Kozani UNESCO Global Geoparks are shown, while the Serifos area is marked with a red square in Figure 1b and described in detail in Figure 2. Other mining sites with exemplary geological and mineralogical characteristics include Stratoni and Olympias at Chalkidiki, and Milos, Syros, and Naxos islands. Modified from Voudouris et al. [34] and references therein.

#### **2. Geological Setting**

Serifos island belongs to the Attic-Cycladic crystalline belt, which represents a polymetamorphic terrane of the Hellenides, in the back-arc region of the Hellenic subduction zone [35,36] (Figure 1). Since Oligocene, slab roll-back resulted in the southward migration of magmatic activity from north to south, in orogenic collapse, and the post-orogenic exhumation of the crust as metamorphic core complexes, associated with voluminous magmatism [36]. The Attic-Cycladic belt comprises four major units, the Cycladic basement, the so-called Basal unit, the Cycladic blueschist unit, and the Upper tectonic unit (e.g., [36–38], Figure 1b). The Cycladic basement includes Pre-Carboniferous schists and Carboniferous gneisses tectonically overlain by the Cycladic blueschist unit consisting of a volcano-sedimentary sequence of metasediments, marbles, calc-silicate schists, and meta-igneous rocks of Permo-Carboniferous to latest Cretaceous ages [35,36]. The Upper tectonic unit consists of various unmetamorphosed Upper Permian to Jurassic volcaniclastics, ophiolites, and carbonates, greenschist-facies rocks of Cretaceous to Tertiary age, and Late Cretaceous amphibolite-facies rocks and granitoids (e.g., [39,40]).

All tectonic units in the Cyclades are separated by crustal-scale detachment faults [21,35,41] (Figure 1b). Three stages of metamorphism during the Tertiary characterize the Cycladic area (e.g., [42,43]): blueschist-to-eclogite facies metamorphism during the Eocene (~52–40 Ma), followed by Eocene-Oligocene (ca. 40–30 Ma) upper greenschist-facies metamorphism, and then, by Oligo-Miocene (25–17 Ma) greenschist to upper amphibolitefacies metamorphism (locally with crustal anatexis at about 17 Ma). The Oligo-Miocene event was accompanied by exhumation of Attic-Cycladic metamorphic core complexes along several low-angle extensional detachment faults, such as the Northern and the Western Cycladic detachment systems, the latter also exposed at Serifos island [21,41] (Figure 1b). Intrusion of various granitoids throughout the Attic-Cycladic belt between 15 and 6 Ma was accommodated by movement of detachments [44,45].

Serifos Island is interpreted as a metamorphic core complex exhumed below the Western Cycladic detachment system [19,20]. The northern part of the island is dominated from base to top by (Figure 2): (1) metamorphic rocks of the Cycladic Continental Basements Unit (CCB) composed of gneiss and mylonitic schists, covered with calcite and dolomite mylonitic marbles; (2) the Cycladic Blueschist Unit (CBU) composed of amphibolites at the base overlain by greenschists with marble intercalations; (3) the Upper Cycladic Unit (UCU), composed of marbles, ankeritized cataclastic shales and schists exposed in the southwestern part, the Kyklopas area, and the northern part, at Platy Gialos [15,21]. These three units are separated by two detachments which both show top-to-the-SSW kinematics, which belong to the WCDS [15]: the Megalo Livadi detachment (MLD) separating the CCB from CBU, is well exposed at Megalo Livadi and Koundouros, and the Kavos Kiklopas detachment (KKD) separating the CBU from UCU which is exposed at Kavos Kiklopas and Platy Gialos [15].

On Serifos, blueschist facies metamorphism dated between 38 to 35 Ma based on 40Ar/39Ar in phengites [46], while all metamorphic rocks have been affected by retrograde LP/HT greenschist facies metamorphism during the Late Oligocene-Early Miocene [15,47,48]. During the Late Miocene the metamorphic pile is intruded by a I-type hornblende and biotite-bearing granodiorite with an age between 11.6 to 9.5 Ma, based on zircon U–Pb dating [22,44,47–50]. The pluton has two distinct facies [15,47,48]: an inner facies which is fine-grained equigranular unfoliated and a border coarse-grained facies with large biotite flakes and mafic enclaves. The pluton intrudes the MLD and the granodiorite roof is deformed by extensional shear zones in the south (Vagia Bay) and east (Agios Sostis) of Serifos [15].

The Serifos granodiorite was emplaced along the West Cycladic detachment fault in the CCB and the CBU units and caused contact metamorphism with the development of hightemperature Ca-Fe endo- and exoskarns and iron ores (Figure 2). Both the Megalo Livadi and Kavos Kyklopas detachment faults acted as pathways by the magmatic-hydrothermal fluids resulting to the development of medium-temperature Ca-Fe-Mg exoskarn zones in

the southwestern part of the island (Figure 2) [15]. Skarns and iron ores demonstrate ductile and brittle structures as a consequence of the activity of the detachment fault [15]. Sulfide ore was formed during the retrograde stage and consists mainly of pyrite, chalcopyrite, galena, sphalerite and is extensively oxidized [14–16,18]. Calcite, barite, garnet, pyroxene, epidote, fluorite, talc, chlorite, adularia are the main gangue minerals [14–16,18].

**Figure 2.** Geological map (modified after Ducoux et al. [15]). HT/MT/LT for high, medium and low temperature, respectively.

#### **3. Results**

The data used in this study have derived from several field trips in Serifos island. During this fieldwork, all identified geosites were assessed and ranked. The geosites (and mining sites) considered in this paper are of great scientific interest, as they provide information about the conditions and timing of metamorphism, the subsequent exhumation paths of the metamorphic core complexes, and the magmatic and hydrothermal processes leading to magma emplacement, and subsequent ore deposition and exploitation, as well

as of crystallization of rare minerals. The geosites (and industrial sites) have been classified based on their physical and scientific characteristics into various categories such as: (a) Geomorphosites, such as landforms resulting from differential erosion and weathering (tafoni), tectonics, drainage network, sea level changes and depositional processes of the geological formations and karstic geotopes, such as caves; (b) Geological, which are also distinguished in petrological or mineralogical geotopes; (c) Tectonics, including detachments, tectonic covers and contacts, faults and folds; (d) Hydrogeological, concerning the springs; (e) Mining heritage. Localities for the various geosites and mining sites at Serifos island are presented in Figure 3 and described in detail in the following paragraphs.

**Figure 3.** Localities of various geosites and mining sites for the suggested Serifos geopark. Geological map modified after Ducoux et al. [15]).

#### *3.1. Geological-Tectonic Geosites at Serifos*

On Serifos Island, geological, tectonic, magmatic, and skarnization processes can be best demonstrated at hundreds of sites, thus making the island a natural geological observatory. Lithological and tectonic contacts can be observed around Megalo Livadi and Kavos Kiklopas, where both the Megalo Livadi and the Kavos Kiklopas detachments are exposed (Figure 4a–d). At these sites, marbles from the CCB, amphibolites from the CBU and schist and serpentinites from the UCU are well exposed. Mylonitic gneisses from the CCB can be observed in the Tsilipaki area and at Trulli (Figure 4e,f).

The I-type granodiorite pluton with its border facies is well exposed around Chora and Vagia (Figure 4g,i), and dacite dikes crosscut marbles of the CCB at Megalo Livadi (Figure 4h). Another igneous body, located in the southern part of the island, was mentioned

by Voudouris et al. [51] as an undeformed leucogranite composed of K-feldspar, quartz, minor plagioclase and biotite and hosts molybdenite-pyrite mineralization (Figure 4f).

**Figure 4.** Field photos showing typical lithologies and tectonic features at Serifos. (**a**) The Megalo Livadi detachment (MLD) separating marbles of the Cycladic Continental Basement (CCB, footwall) from amphibolite and gneisses of the Cycladic Blueschist Unit (CBU, hanging wall). Note the location of Fe-mines beneath and along the detachment fault; (**b**) the MLD separating marbles of the CCB from hedenbergitic skarn hosted in brecciated amphibolite of the CBU at Koundouros area; (**c**,**d**) the Kavos Kiklopas detachment (KKD) separating mylonitic marbles of the CBU (footwall) from metaophiolites and schists of the Upper Cycladic Unit (UCU); (**e**) panoramic view of the mylonitic orthogneiss of the CCB at Trulli area (view from W to E); (**f**) undeformed S-type (?) granitoid (leucogranite) at Trulli area intruding the mylonitic orthogneiss; (**g**) I-type granodiorite (border facies) at Vagia area; (**h**) dacitic dikes crosscutting Fe-oxides stained marbles of the CCB at Megalo Livadi area; (**i**,**j**) I-type granodiorite including high-T endoskarn garnet-pyroxene-magnetite bodies (dark areas) intruding white and grey marbles of the CCB at Chalara area; (**k**) medium-T hedenbergite skarn crosscutting epidotized amphibolite at Avessalos area; (**l**) modern galleries within oxidized ore hosted in schists and marbles of the CBU at Galani area (Moutoula, Pyrgos).

High-temperature endo- and exoskarns, medium-temperature distal exoskarns with prograde and retrograde assemblages including iron oxides and sulfides occur among others at Chalara (Figure 4i,j), Agia Marina, Megalo Livadi, Avessalos (Figure 4k) and Moutoulas (Figure 4l). Additional sites and photos with petrological and mineralogical characteristics are demonstrated in the following paragraphs.

#### *3.2. Mineralogical and Petrological Geotopes at Serifos*

Serifos is not only famous because of the mining activity in the past, it also shows unique mineralogical and petrological features: its very rare and worldwide known skarn minerals (e.g., garnets, quartz and its green variety called prase, ilvaite; Figures 5–9), attracted scientists and mineral collectors from all over the world. This has led to a dramatic reduction in the abundance of the mineral occurrences of the island, making their preservation necessary. The Serifos skarn is unique in the world containing the best varieties of prase (e.g., the green quartz variety) and ilvaite [24–30].

**Figure 5.** Field and hand specimen photos showing typical petrological and mineralogical features of geotopes at Agia Marina (a to j), and Koutalas (k to o) areas. (**a**) Panoramic view of Agia Marina area from N to S with mylonitc orthogneiss outcrop; (**b**) mineralized geode within hedenbergitic skarn surrounding orthogneiss; (**c**) quartz crystals from the previous geode; (**d**,**e**) garnetite (andraditic skarn) hosted in orthogneiss at the contact to I-type granodiorite (view from N to S and E to W respectively); (**f**–**h**) garnetite with idiomorphic andradite and late quartz crystals; (**i**,**j**) geode within hedenbergite filled with quartz crystals, occasionally amethystine at their basis; (**k**) I-type granodiorite (inner facies) at the Kastro Grias area (view from S to N); (**l**) hydrothermal breccia composed of sericite-altered granodiorite fragments within a matrix of Fe-oxides and barite at the Kastro Grias locality; (**m**) Fe-Pb mines within marbles of the CCB; (**n**,**o**) barite crystals with galena and Fe-oxides at the Koutalas mines.

**Figure 6.** Field and hand specimen photos showing typical petrological and mineralogical features of geotopes at Megalo Livadi area. (**a**–**c**) Panoramic view (from S to N) showing marbles of the CCB and hedenbergite skarn separated by the MLD fault. Note location of mine within marbles just beneath the detachment fault; (**d**,**e**) hand specimens with calcite rhombohedron coated by quartz associated with hedenbergite; (**f**) hand specimen with quartz crystals coated with Fe-oxides; (**g**) hand specimen with barite crystals covered with calcite; (**h**) panoramic view (from N to S) showing location of ilvaite in the hedenbergitic skarn on the road towards Megalo Livadi; (**i**) hedenbergite followed by ilvaite and then by quartz being part of breccia cement of the cockade megabreccia in the previous locality; (**j**) amethyst and prase as late open-space filling in geodes of the hedenbergite bearing megabreccia.

Quartz is a very common mineral in the skarns of Serifos. Combinations of amethyst and prase forming scepter growths at Serifos are worldwide unique specimens. Garnet is a major constituent of skarn and represented by several varieties at Serifos. The Serifos andradites are famous due to their zonal growth with colors ranging from deep brown to orange. Ilvaite, up to 50 cm long in association with hedenbergite at Serifos, represent the best occurrence of this mineral worldwide. Calcite crystals up to 35 cm are intergrown with prase at Serifos. The carbonate-replacement deposits at Serifos contain large crystals of fluorite (up to 5 cm) and barite (up to 50 cm). Native bismuth in grains up to 5 cm occurs at Moutoulas, near Galani in the northern part of Serifos island. A list of all known collective minerals in Serifos, including primary, supergene as well as slag minerals are presented in Table 1.

**Figure 7.** Field photos showing typical petrological and mineralogical features of geotopes along (**a**) the Megalo Livadi-Koundouros geotrail; (**b**) magnetite replacing marbles of the CCB; (**c**) panoramic view (from SW to NE) of the Koundouros geosite, showing mineralized marbles of the CCB, and hedenbergitic skarn on both sides; (**d**,**e**) hedenbergitic skarn developed in several growth zones around fragments of amphibolite; (**f**) prase and hematite (iron roses) in cavities of hedenbergite; (**g**) the Megalo Livadi detachment (red dotted line) separating Fe-oxide mineralized marbles of the CCB from amphibolite-hosted hedenbergitic skarn of the CBU. Note the location of mine entrances just beneath the detachment fault; (**h**,**i**) ilvaite crystals developed in geodes within hedenbergitic skarn at the Koundouros geosite.

In addition, under the microscope, the minerals arsenopyrite, sphalerite, cobaltite, glaucodot, gersdorffite, marcasite, native Au and native Bi and sulfosalts of the bismuthiniteaikinite series were identified in southwestern Serifos mineralization by Korisidis et al. [18] and Bi- and Te-rich tetrahedrite-tennantite solid solutions, greenockite tellurides, tetradymite, hessite, and melonite are additionally mentioned by Fitros et al. [16]. Beyerite, bismutite, and bismite replaced native bismuth at Moutoulas, and together with covellite, cerussite, anglesite, chalcocite, goethite, are products of the supergene stage.

**Figure 8.** Field and hand specimen photos showing typical petrological and mineralogical features of geotopes at north (**a**–**f**) and south (**g**–**m**) Avessalos area. (**a**) Panoramic view from W to E with location of dark green prase crystals and red-colored andradite within hedenbergite skarn. Marbles of the CCB can also be seen; (**b**) panoramic view from E to W with outcrops of mineralized geodes within hedenbergite skarn; (**c**,**d**) hedenbergite with geodes filled by red andradite; (**e**) hand specimen with red andradite on hedenbergite both covered by green quartz (prase) (photo courtesy of B. Ottens); (**f**) hand specimen of dark green variety of quartz with hematite roses at its base; (**g**) panoramic view from W to E with location of light green prase crystals and amethyst scepters within hedenbergite skarn at south Avessalos; (**h**–**j**) goesite with huge geodes within hedenberite filled with prase, at the previous locality; (**k**) hand specimen of prase crystals with orange-colored upper parts due to iron oxide inclusion; (**l**) hand specimen with amethyst scepter on prase; (**m**) hand specimen with intergrowth between prase and platy calcite.

**Figure 9.** Field photos showing typical petrological, mineralogical and mining features of the geotope at Chalara area. (**a**) Panoramic view (from S to N) showing marbles of the CCB intruded by Itype granodiorite. Note location of garnet-pyroxene-magnetite endoskarn within the granodiorite; (**b**) granodiorite veins intruding marbles of the CCB; (**c**) garnet-bearing endoskarn of granodiorite sill intruding marbles of the CCB; (**d**) garnet-pyroxene exoskarn within layers of CCB marbles; (**e**) pyrite-magnetite mineralization associated with garnet-pyroxene endoskarn within granodiorite; (**f**) pyrite-magnetite mineralization within exoskarn.

The SW part of Serifos island, including the Agia Marina-Koutalas, Megalo Livadi-Koundouro and Avessalos subareas, displays all the criteria necessary to be characterized as a mineralogical and petrological geotope [25–27,52,53].

The Agia Marina area is dominated by mylonitic gneisses of the CCB intruded by granodiorite veins and sills transformed to granatitic endoskarn bodies (Figure 5a–l; see also Ducoux et al. [15]). The geotope includes splendid occurrences of andraditic garnets (crystals up to 5 cm in size) formed during the prograde stage in association with quartz crystals crystallized during the retrograde skarn stage (Figure 5c–h). Quartz (often amethystine) is associated with hematite in quartz veins crosscutting garnetite or hedenbergitic skarn (Figure 5i,j). Towards the Kastro Grias locality, a brecciated granodiorite with iron oxide and barite in the breccia matrix is exposed (Figure 5k,l). At the adjacent Koutalas area, the Fe-Pb mines within marbles of the CCB contains large barite crystals (up to 30 cm), in associated with galena (Figure 5m–o).

The Megalo Livadi-Koundouro area is dominated by several Fe mines hosted within medium temperature hedenbergitic skarns and CCB marbles, following the trace of the Megalo Livadi detachment (Figure 6a–c). Magnetite was formed during the retrograde stage and followed by pyrite-arsenopyrite-chalcopyrite-Bi-Au mineralization [18]. Retrograde minerals also include calcite, quartz and barite (Figure 6d–g). At about 1 km NE of Megalo Livadi, a cockade megabreccia is composed of epidotized amphibolite fragments, rimmed by several bands of prograde hedenbergite in association with ilvaite, followed by quartz (also amethystine) and late calcite (Figure 6h–j). The Koundouros locality is characterized by hedenbergitic skarn including the best ilvaite crystals worldwide. Geodes within the skarn are filled by idiomorphic crystals of ilvaite, hematite (iron roses), quartz and calcite. The ilvaite crystals are associated with hedenbergite, forming radial aggregates reaching sizes of up to 50 cm (Figure 7).


**Table 1.** List of collective minerals from Serifos island (data from Ottens and Voudouris [28] and this study).

The Avessalos area is the best site in the world in respect to the mineral green quartz (prase). Similarly to Megalo Livadi-Koundouro, at Avessalos, the mineralization occurs in geodes developed within a cockade megabreccia just below the Megalo Livadi detachment, formed around epidotized amphibolite, subsequently covered by hedenbergite and garnet during prograde skarnization and by quartz during the retrograde stage. The northern Avessalos geosite was discovered 20 years ago and represents the best locality of the mineral prase, the green variety of quartz [24]. The crystal forms, intergrowths and sizes (up to 40 cm) of green quartz specimens from this locality are unique. Similar crystals have never been observed elsewhere in the world. The very deep green-colored prase crystals are accompanied by iron roses. The northern Avessalos area is characterized by a granatitic and hedenbergitic exoskarn and by the development of huge geodes filled by

prograde and retrograde skarn minerals (Figure 8a–f). Zoned andraditic garnets occur in this location, but the spectacular specimens of green quartz and amethyst are those which attracted the interest of mineral collectors in that geosite. In the double-colored crystals of prase-amethyst, the transition between these two crystals is abrupt within the same crystal, where prase occurs at the base and amethyst at the top of the crystal. The amethysts are transparent and of gemstone quality [30,54–56].

The second geosite is located at the southern part of the Avessalos area (Figure 8g,h). This geosite includes large geodes, containing unique quartz crystals, not only in respect to their quality but also for their crystal forms, which reflect very special growth conditions (Figure 8i–l).

Rare combinations of prase-amethyst scepter crystals contain phase alternations, including transitions from prase towards amethyst, and finally, to prase even within a single composite crystal [30,54–56]. Scepters include both normal and reverse forms. Calcite-prase intergrowths, abundant within the southern Avessalos geodes, were found for the first time in Serifos island: calcite crystals, either as rhombohedron, or in platy forms alternate with the prase suggesting contemporaneous deposition probably during boiling processes (Figure 8m). The Avessalos area underwent extensive mineral exploitation by local and foreign dealers, often destroying scientific information on the geological evolution and valuable elements of the geocultural heritage.

The Chalara locality best demonstrates outcrops of high-temperature endo- and exoskarn and of typical prograde and retrograde skarn sequences as described in the literature (e.g., [57,58]). Skarn formation is related to intrusion of granodiorite (Figure 9a–d), whereas at places granodiorite sills intruding marbles of the CCB are totally transformed to garnetites (Figure 9c,d). Pyroxene accompanies garnet during prograde skarn formation followed by magnetite and then by pyrite in the retrograde stage (Figure 9d–f).

#### *3.3. Geomorphological–Hydrogeological Geosites at Serifos*

The geotopes considered in this paper as geomorphosites include a variety of geomorphological landscapes. The lithology of Serifos consists of various lithological formations with different resistance in erosion and weathering, which in combination with the action of the hydrographic network and tectonics, has created the geomorphosites (tafoni) located in the NW part of Serifos' coast (Figures 3 and 10). The increased presence of halite indicates a salt-induced weathering (humidity and seawater spray) that plays an important role in their development.

Additionally, karstic geotopes, such as caves are areas with unique characteristics and archaeological findings. The Koutalas cave is decorated with stalactites and columns, while the next chamber is covered almost along its entire length by a small lake.

In the coastal zone, the most characteristic geomorphosites are due to deposition processes with notable examples of coastal dunes, tombolo (Figure 10), as well as lagoon in the Tsilipaki area.

The hydrogeological geotopes include rivers, a number of springs (created by the discontinuities of the granite), fountains and wells and the presence of hot springs such as the Almyros springs near the old loading facility of Megalo Livadi (Figures 3 and 10). During the mining period, the Mining Company had built stone baths for therapeutic purposes.

**Figure 10.** Field photos showing typical geomorphological features of geotopes at Serifos. (**a**) Tombolo at Agios Sostis; (**b**–**d**) landforms resulting from differential erosion and weathering (tafoni) at Skala, Moutoula and Sykamia, respectively; (**e**,**f**) the hot springs of Almyros area.

#### *3.4. Mining Heritage of Serifos*

Serifos was aptly named "the iron island" among the Cycladic islands, due to the flourishing of the iron industry. Iron ore mining activities have been witnessed in Serifos since antiquity. Minoans and Mycenaeans developed mining activities here, which continued during Roman times and Venetian domination from the 14th to 16th century. Prehistoric clay kilns have been identified in Avessalos in the Phournoi area and on the Kefala peninsula, a fact that testifies the extraction and processing of ore in the early stages [32,33]. Copper minerals are more frequent in the southern part of the island in association with the magnetite-hematite deposits [18]. Unique in Greece are the kilns that melted iron and copper in various places on the island [32,33]. By far the largest known copper slag heap in the Aegean area is that of Skouries at Avessalos with estimates of about 100,000 tons of slags present. Kefala and Phournoi with several hundred tons and a few tens of tons of slags, respectively, are minor compared to Skouries [32,33]. In addition to copper and iron ores, galena-rich ores are known in the northeastern part of Serifos at Moutoula (Figure 4l) and Pyrgos close to Galani. The Moutoula deposit was exploited in the 19th century for galena, while a possibly earlier undated gallery has also been noted [31].

Modern mining of the district started from 1861 and the iron ore mines finally ceased operations in 1965 [59,60]. From 1861, and systematically, from 1869, began the extraction of iron ores by the Hellenic Mining Company, which remained there until 1875. After 1880, the French company Serifos-Spiliazeza proceeded to intensive exploitation of the deposits of Serifos [59,60]. Andreas Sygros and Giovanni Baptista Serpieri were involved in its operation. In 1886, the German miner Emilios Groman took over the management of the company Serifos-Spiliazeza and essentially all the mines of Serifos [59–63]. The Gromans effectively controlled the island, while building extensive infrastructure for the extraction, transport and loading of ore on ships. From 1869 to 1940, a total export of 6.59 × <sup>10</sup><sup>6</sup> tons of iron ore (e.g., hematite, limonite and magnetite) from several mines mainly in the southwestern part of the island was made (Figure 11). When Grohmann undertook the operation of the mines, the headquarters of the company were transferred to Megalo Livadi, where a two-story neoclassical building with architectural elements of the "Ziller" style were created, ruins of which still stand at the end of the beach today (Figure 11d). Megalo Livadi was the main iron ore export harbor of Serifos, equipped with all the necessary sorting and shipment facilities (Figure 11a,b).

**Figure 11.** Field and underground photos showing evidence of mining activity at Serifos. (**a**,**b**) Loading bridges at Megalo Livadi; (**c**) entrance of gallery at Megalo Livadi; (**d**) the headquarters of the iron ore mines at Megalo Livadi; (**e**) loading bridge at Koutalas; (**f**) mining wagon in a Koutalas mine.

The Ministry of Culture declared the following as historical monuments: the Headquarters of the mines, the loading bridge in Megalo Livadi, the ore loading bridge in Koutalas, the workers' residencies, as well as any kind of equipment that remains to provoke memories of the flourishing of the island in another era (Figure 11). The activities of the mines in their three-thousand-year history have left behind monuments and residential complexes, which are an important part of the pre-industrial history of Greece [63]. They are an important testimony of the industrial activity that had been developed on the island and are of historical, architectural, and sociological interest.

Serifos is in itself an Open Air Museum of mining activity since its hinterland is engraved with mining galleries, its ports have been turned into loading stations of its minerals, and its social and economic history is timelessly tied to the mines [63]. All the facilities created from 1869 to 1964, including the loading ladder, the hydromechanical enrichment complex, the engine room with the equipment of the workers' houses of the 19th century and a newer house complex from 1950 are preserved in the mining center of Koutalas. The ruins of a residential complex and a loading ladder are preserved along the coast in Chalara. West of Koutalas, in Aspros Kavos, dozens of galleries reach sea level. Dozens of galleries and transport routes are maintained throughout the area. In the bay of Avessalos, there are ruins of a loading ladder and mining facilities, and in the place Aerata, traces of ancient piles of slag and carved basins in the rocks for the cleaning of the ore can be found. The installations date from the 4th century BC. In the area of Mountaki, a large gallery was built, 1400 m long, which connected it with Kalogeros. The gallery served the transport of the ore from Kalogiros to the loading ladder in Mountaki.

#### **4. Discussion**

#### *4.1. The Possibilities of Geotourism Development in Serifos—Geotourism Perspectives*

Geoparks are wider areas that contain significant sites of geological monuments and geotopes as well as sites of ecological, archaeological, historical or cultural interest and are tools for environmental education [6,11–13,64]. Geoparks are of particular scientific interest since the purpose of their existence is to explore the relationships between geological, natural and cultural heritage. Serifos has been included in the Atlas of the Aegean geological monuments of the Ministry of the Aegean since 2002 with the Koutalas Cave, the Mineral occurrences and Iron Mines [65].

The inclusion of Serifos as a future UNESCO Global Geopark will highlight the concept of geotopes, the scientific–educational–touristic interest they raise, and the values they advocate (geo-conservation, geoprotection) contributing to the development of geotourism.

Green values of the cultural and natural heritage of the Serifos island, and therefore, the interest about it may be briefly highlighted as follows:

Geological and mineralogical value: Interesting geology with noticeable scientific and educational values. The area presents an impressive variety of minerals. In Serifos, they also found some rare and highly developed crystals for their kind of minerals, such as green quartz, amethyst, ilvaite, hedenbergite, garnet, calcite and barite.

Mining and metallurgical value: By far the largest known copper slag heap in the Aegean area is that of Avessalos on Serifos, with estimates of about 100,000 tons of slag present.

Environmental value: Interesting and important types of ecosystems and habitats as well as numerous and/or important flora and fauna species are also found. Areas of Serifos Island have joined the Natura 2000 network, such as GR4220009 South Serifos and GR4220029 coastal zone and the islands Serifopoula, Piperi and Vous.

Industrial value: The mines of Serifos are an example of an industrial monument and present a uniqueness, since the mineral areas of the island were mainly exploited in three different periods (prehistoric period, 14th century and from 1869 to 1963).

Historical value: Serifos is in itself an Open Air Museum of mining activity since its hinterland is engraved with mining galleries, its ports have been turned into loading stations of its minerals, and its social and economic history is timelessly tied to the mines.

Social value: With the influx of workers, Serifos became the center of the early Greek trade union movement contributing greatly to the shaping of the Greek trade union culture [61,62].

Archaeological and cultural value: In historical times, the presence of circular towers, such as Aspropyrgos in the bay of Koutalas, and other buildings may be associated with mining and metallurgical activity on the island. Prehistoric clay kilns have been identified at Moutoula, on the northern slope of Vigla hill, on Avessalos in the Phournoi area and on the Kefala peninsula, which testify to the extraction and processing of ore in the early stages.

Aesthetic value: The two-story neoclassical building, with architectural elements of the "Ziller" style in Megalo Livadi. Mineral species of extraordinary aesthetic and scientific value suitable for exhibition in museums and collections.

Nowadays, geotourism has proved to be a new and much promising trend for the whole district. The geotouristic development of mineralogical and petrological geotopes at Serifos ensures the preservation of the geological heritage of Serifos Island and also offers the opportunity for sustainable development.

The Serifos geotopes belong to the Greek mineralogical and geological heritage and can be considered as mineralogical treasures, some of them unique throughout world, as listed below (see also Figures 2–11):


#### *4.2. The Proposed Network of Geocultural Routes of Serifos (Geotrails of Serifos)*

During the present study, six geotrails—georoutes of exceptional mineralogical and petrological interest—have been developed during field and laboratory work using GPS and geographical information systems (GIS) to link these geotopes with the cultural and ecological sites. Figure 12 and Table 2 demonstrate the proposed network of georoutes (total length: 30 km) and the geotouristic comparative advantage of the island. Along the routes, the geodiversity is interpreted, including its relationship with the surrounding historical and industrial activity of the region. These geotrails—georoutes include the Agia Marina-Koutalas, Megalo Livadi-Koundouros, Pyrgos-Galani and the Avessalos area—form part of the proposed Serifos geopark.

The geotrails are involving stopping places which help us find out more about the variety of geology in the area and see a different side to the scenery. This includes site interpretation panels, training courses and other educational and interpretative activities that do not demand large financial and/or organizational investments, but could significantly benefit visitors' activities in the park [66,67]. Good interpretation and educational activities could attract more visitors, especially non-experts or casual geotourists [67,68], who do not possess great knowledge of geology and other similar topics. Interpretation is a vital part of how people experience the places they visit, as it explains the natural and cultural heritage and brings them to life. Interpretative methods could be divided in two categories [68], depending on the location of their implementation:


**Table 2.** Geotrails of Serifos.


**Figure 12.** The routes of geotrails suggested for the Serifos geopark. Geological map modified after Ducoux et al. [15].

In this case study of the Serifos geopark, both of these methods could be used. Visitors should be able to see and hear many scientific facts not only about mining, but also about history and the time period in which they worked. Other educational activities could include different programs for visitors, such as the junior mineralogist program in which children take part in simulated excavations. The main idea behind these projects would be to enable learning through practice. The most effective tools for interpretation and visitor involvement could include guided tours to the mining sites, workshops (e.g., simulated mining, mineral identification, etc.), or multimedia performances. Besides interpretation and education, the park should also support the local people in producing and selling their local products and souvenirs [67,71].

Interpretation therefore needs to meet the requirements of a broad spectrum of audiences from the specific site-related geological and educational information for the dedicated geotourist and those actively seeking to learn about the geology of an area.

The suggested routes are the first geo-walking paths of the area, in which an Outdoor Geological Museum can operate, in the context of the proclamation of the wider part of the island as a geopark. Many of the entrances to the old network of underground mines remain open on the hillsides around. The terrain on the routes consists mainly of a variety of quiet roads and paths across fields. These paths were further examined in order to highlight the geological sites and to characterize both the individual sites as geotopes and the wider area as a geopark. The georoutes, where possible, followed the existing network of the island. The old Hiking Network of Serifos Island has a logo that connects the history and nature of the island, as in ancient times, the frog was the symbol of the island. In addition, the title "Iron and stone paths" reflects the geology of the island, but also its mythology, during which Perseus with the head of Medusa petrified the whole island [63].

#### *4.3. Serifos: A Potential New Unesco Global Geopark*

There are six UNESCO Global Geoparks in Greece: Lesvos island, Psiloritis and Sitia in Crete, Chelmos-Vouraikos at Peloponnese, and Vikos-Aoos in Epirus and Grevena-Kozani (e.g., [11,72–75]) (Figure 1). These geoparks combine extraordinary geological, paleontological, and natural features. The proposed Serifos geopark is an area enclosing features of special geological significance, rarity or beauty. However, the potential Serifos geopark combines spectacular mineralogical, petrological, geological, mining, cultural characteristics and can be described as a polythematic geopark.

Besides the above mentioned six geoparks, similar geological projects in Greece include: the Syros island, Cyclades complex, as a prime locality for the study of processes active in deep levels of orogeny and is world famous for its exceptionally well-preserved glaucophane schist-to eclogite-facies lithologies [76]; the Meteora and Mount Olympos in central Greece with legendary geological history and mythology [77,78]; the Kefalonia, Ithaki Lefkas and Meganisi islands, in the active geotectonic region of the Ionian Sea, Western Greece and in the convergent zone between the African and Eurasian plates [79]; the Naxos island in the Cyclades, characterized by intense mining and quarrying activities, since the antiquity and by distinctive geological and mineral wealth [80].

The suggested Serifos geopark is also comparable to the Lavrion geopark, which in addition to mineralogical, petrological, geological, mining and cultural features also displays worldwide unique archaeological characteristics [34].

Worldwide, a research on mineralogical, petrological and mining heritage, comparable to that of Serifos has been demonstrated: in post-mining areas of central Mexico [81], Poland (Gold Mine in Zloty Stok), Spain (La Tortilla Mine in Linares), UK (King Edward Mine, in Cornwall) [82], Italy (the Traversella Mining Site at Piemonte, Italy) [83]; in petrological and mineralogical geosites such as granite landforms of Seoraksan Mountains, Republic of Korea [84]; the Monviso Massif and the Cottian Alps in Piemonte, Italy, with some of the best preserved ophiolites in the Alps and associated Cu–Fe mineralizations, the first primary source of jade in the Alps, the world-famous minerals such as coesite and giant pyrope, as well as type localities for new minerals [85]; the eastern limb of the Bushveld Igneous Complex, South Africa, with layered ultramafic-mafic rocks, metamorphic aureole outcrops, orebodies of chromitites, PGE reefs, etc. [86].

The Serifos geopark is designated with a focus on three main components: the protection and the conservation of Serifos' heritage, the tourism-related infrastructural development and the socio-economically sustainable development of the local community using a sustainable territorial development strategy. Heritage sites within a geopark can be related not only to geology but also to archaeology, ecology, history and culture. All these sites in the Serifos geopark constitute thematic parks and will be linked in a network with routes, trails and sections that should be protected and managed. The mineralogical "treasures" of Serifos Island, featuring in a worldwide unique hedenbergite-ilvaite-garnet-prase-bearing skarn, and the unique geological structure of the island, due to specific tectonic processes, makes it a special site with great archaeological, as well as aesthetical, cultural and scientific value. Some specific actions should be developed such as a management plan of the Serifos geopark and a clear presentation of the geotopes of Serifos and their quantitative assessment. The aim of a quantitative assessment is to decrease the subjectivity associated with any evaluation procedure. The result of this numerical assessment is a sorted list of sites, which is a powerful tool for the establishment of management priorities. Inventorying and quantitative assessment, statutory protection, conservation, promotion and interpretation and monitoring of sites are some specific methods used to promote geoconservation.

The suggested six geotrails–geocultural routes are of exceptional mineralogical and petrological interest, and have been developed in order to discover the natural, geological and cultural treasure of the island. Along the routes, the geodiversity is explained, including its relationship with the surrounding biodiversity, and the historical and cultural aspects of the region. The southwestern part of Serifos forms a wide network of habitats for the flora and the rich fauna of the region because of the combination of its geomorphological and hydrogeological features. Serifos and particularly its southwestern part is also included in the European network of protected areas NATURA 2000, which is the main national means for the purpose of Directive 92/43/EEC of the European Council "for the conservation of natural habitats and wild fauna and flora" which are significant at the European level [87]. The region, as the whole of the Cyclades islands, is a passage of sea turtles and migratory birds and there are seasonal hunting restrictions. Almost half of the island is covered by typical low Aegean phrygana. There are also sand dunes with characteristic vegetation. The hydrographic net of the site includes rivers with N–S direction and a total length of about 14 km. It also includes a number of springs, fountains and wells.

The combination of its rich morphological relief and the ancient and historical monuments—in the western part of the region, there are abandoned mines, which have been characterized as historical monuments—gives great value to the region, which requires special protection.

The suggested geotrails can be important management and interpretative tools for geotourism development. The selection of the content is not limited to natural and historical information but incorporates the geoenvironment with the cultural character of the landscape, as the design goal of this touristic product is the perception of timelessness of space. While designing a matrix of geotrails–geocultural routes the old path networks are revealed, activating at the same time the local community. In these routes, tourists through experiential activities turn into travelers, exploring the features of a place, creating experiences and, finally, emotional binding.

A necessary condition for the integration of the proposed network of georoutes with the aim of highlighting the geodiversity and the mining history of Serifos is the perfect organization of the marking and its annual maintenance by the municipality.

The municipality of Serifos will install new signs (information signs and direction signs). In addition, it will be instrumental the procurement and placement of interpretive panels for geoheritage and display of the relief of the island using 3D printing technique. Signage is an integral part of the construction and operation of a Hiking Trail Network. In order to hike the geotrails, a walking map is recommended that contains detailed maps and short descriptions of the waypoints on the route.

The inclusion of Serifos in the network of Global Unesco Geoparks is a basic goal of the municipality. In Megalo Livadi, there is a small museum of minerals and rocks of Serifos, while some samples of minerals are also exhibited among the other exhibits of the folklore museum of Chora. As a place for the creation of an open-air museum, Megalo Livadi is proposed, in which all the facilities that were built between 1869–1875 by the Mining Company are preserved. The facilities of the neoclassical building (command post), the workers' residences, towers, explosives depot, rails, wagons, galleries, stairs will be restored and will be highlighted with modern museum teaching materials and will be the central core and the open part of the Museum [63]. Megalo Livadi is located in the center of an extensive area of special historical interest.

The works that will be required for the creation of the museum include restorations of buildings, landscaping, fixing and maintenance of metal structures (e.g., loading ladder, tipping pylons, etc.), reconstruction of railway networks, fixing and highlighting selected galleries, decoration uniting the basic cores of the museum, etc.

Nowadays, the historic building of the neoclassical building is being reconstructed and upgraded to a cultural/conference center and a museum of mineral wealth and mining history. A series of exhibits will be exhibited in the historic building, including collections of rocks and minerals, information and educational materials will be displayed and educational seminars and workshops will be organized. Exhibition sections will be developed at the headquarters regarding the geological and mining image of Serifos, its mineral wealth, the history of quarrying operations from antiquity to modern times, the productive process of exploitation of mineral wealth, social and economic context, as well as the workforce. With its operation, Serifos will be promoted and will be promoted worldwide through conferences, seminars and other special events, in order to attract visitors with special interests but also to inform the local community about its history and the identity of its place.

The touristic infrastructure of Serifos is well developed. It includes, besides the famous beaches, a lot of hotels and private accommodations, traditional restaurants, and water sport possibilities, as well as other leisure and sportive activities (diving).

Serifos island is a unique site for education and research in several disciplines, such as geological investigation, prospecting, mineralogy, geochemistry, mining, metallurgical processes, economic, political, and social sciences. Serifos provides an almost inexhaustible field of activity for scientists and the public, and also offers ideal opportunities for educational and geotourism. We conclude that Serifos Island meets all the scientific, educational, cultural, and touristic criteria that makes the area highly suitable for its development as a UNESCO Global Geopark.

#### **5. Conclusions**

Serifos is a geographical unity which represents the combined work of nature and humans depicting the evolution of the local society under the influence of the physical constraints of this island area. It is characterized by a worldwide unique geological, petrological and mineralogical diversity, combined with a very rich cultural heritage, biodiversity and folk tradition. The Serifos geotopes belong to the world mineralogical and geological heritage and should be protected from further commercial exploitation. The geotouristic development of the geological, mineralogical and petrological geotopes at Serifos, combined with the foundation of a mineralogy-petrology museum, ensures the preservation of the geological heritage of Serifos Island and also offers the opportunity for sustainable development.

The present paper focuses on exemplary mineralogical, geological and mining features of Serifos, and presents six geotrails which have been developed to link the geological heritage with cultural and ecological sites. The suggested Serifos geopark focuses on the promotion of the geological and mining heritage of the island, with the aim of integrating Serifos in the network of Global Unesco Geoparks, in the near future.

**Author Contributions:** Conceptualization, N.V. and P.V.; methodology, N.V.; investigation, N.V.; resources, N.V. and P.V.; writing—original draft preparation, N.V.; writing—review and editing, N.V. and P.V.; supervision, P.V. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Acknowledgments:** The authors gratefully thank Maxime Ducoux for kindly providing his geological Serifos map. We also gratefully thank the journal editor and the two reviewers for their thorough consideration of this paper.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**


**Katia Hueso-Kortekaas 1,2 and Emilio Iranzo-García 3,\***


**Abstract:** Salinas and saltscapes are relevant geoheritage sites with important implications on socioeconomic activities beyond the production of salt, particularly tourism and education. As cultural landscapes, they also have implications related to the identity of their communities. This work presents the study of the patrimonialization processes of four sites in Europe (Añana in Spain, Guérande in France, Læsø in Denmark, and Seˇcovlje in Slovenia). Lessons obtained from these processes may contribute to the recovery and valuation of similar saltscapes and other forms of geoheritage. The study is based on interviews with relevant stakeholders, a survey of the related grey and scientific literature, and a simplified SWOT analysis. Despite their differences in historical background and current management, all four sites share features that have contributed to the success of their patrimonialization processes, such as having a dedicated entity for this purpose or being protected in some way. They also share common threats that need to be addressed, such as the banalization of the heritage discourse. Other saltscapes and geoheritage sites in general may benefit from these common features, which should serve as an inspiration and not as a template. In the end, shifting from a little-known productive, (proto-)industrial activity toward a sustainable, multifunctional landscape in which geoeducation and tourism are paramount contributes to a more resilient and educated society.

**Keywords:** salinas; saltscapes; geoheritage; cultural landscapes; geotourism; geoeducation; local development

#### **1. Introduction**

Salinas are a cultural landscape type. Within the context of this paper, salinas can be defined as productive landscapes in which salt that is present in nature and forms a saline ecosystem is harvested by humans by means of different techniques (solar evaporation, seething, etc.). Cultural landscapes, on the other hand, are a blend of nature and culture, tangible and intangible heritage, and geological, biological, and cultural diversity, embodying a framework of complex relationships. The recognition of landscape as a cultural heritage, as the perceived and interpreted manifestation of a territorial reality loaded with values, reveals its protagonism in different spheres: environmental, cultural, identitarian, economic, and educational. The preamble of the European Landscape Convention (2000) indicates that the landscape plays an important role of general interest in the cultural, ecological, environmental, and social fields, and that it constitutes a favorable resource for economic activity. Its protection, management, and planning can stimulate the creation of employment. It also indicates that the landscape has a fundamental role in shaping local cultures and that it is an essential component of the European natural and cultural heritage, contributing to human well-being and to the consolidation of European identity [1]. Therefore, landscapes can and should be considered as a key element for the integral development of the individual and the community [2,3].

**Citation:** Hueso-Kortekaas, K.; Iranzo-García, E. Salinas and "Saltscape" as a Geological Heritage with a Strong Potential for Tourism and Geoeducation. *Geosciences* **2022**, *12*, 141. https://doi.org/10.3390/ geosciences12030141

Academic Editors: Hara Drinia, Panagiotis Voudouris, Assimina Antonarakou and Jesus Martinez-Frias

Received: 11 February 2022 Accepted: 14 March 2022 Published: 21 March 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

Saltscapes or salt landscapes are the result of the interaction between geologicalgeographical processes and socio-economic dynamics that, because of their multiple values, turn the territory into a "cultural geoheritage" that must be conserved, rationally managed, and taught [4]. These areas, full of geodiversity, interconnect territories, their people, and their culture. Salinas, a term that in this context refers to the salt architecture and productive activity that gives rise to saltscapes, are the result of an ancestral economic activity, based on geological resources, which in their development have generated unique ecosystems. However, not all salinas have the same characteristics, present the same model of productive activity, or have the same state of conservation. While some are in full production and are well preserved, others are in decline, endangering ecosystems, cultural heritage, and, ultimately, the landscape. In both cases it is necessary to devise valorization strategies, either to maintain the ecosystem and reinforce its social recognition, or to provide the salinas with new uses, such as tourism or education, that prevent their degradation and disappearance.

Tourism has established itself as an important economic and social activity in almost all scenarios, with emphasis on the segments related to nature and culture [5]. It is a wellknown fact that tourism and cultural heritage do not always get along well, but they are mutually interdependent. How to solve this paradox? How can tourism contribute to the conservation of heritage, and to the education and livelihoods of residents? Heritage can be "activated" for the purpose of tourism [6] and heritage tourism, in turn, can contribute to create identities, not only among tourists but also within the local community. This is no trivial issue: in places where the identity of a community was linked to a certain economic activity (industry, mining, agriculture, etc.) that has subsequently disappeared, there is a threat of "dissolution of the society" (unemployment, emigration, ageing, etc.) and the local community's identity may need to be reactivated. Heritage tourism is one of the possible tools to do so [7].

However, tourism in heritage sites or cultural landscapes is an activity that carries controversy among conservationists because they see it as a threat to the values they defend, but also as a source of necessary income to preserve cultural heritage [8–10]. This tension needs special attention when taking into consideration sustainability [9]. It is also relevant to see to what extent the profits of heritage tourism reach the local community and the resources they depend on [11]. From the point of view of tourism development, heritage has some virtues: it can be overtly promoted by public administrations; it is—in principle—free of charge and owned by society in general; it can be visited almost any time of the year; and it offers an air of respectability to the travel experience. Despite these tensions, as said, authorities and the private sector tend to see heritage tourism as a tool to enhance the economic activity in their area of reference, and even as an educational tool. Current tourists originating from a post-industrial society, often seek meaning in their activity. This type of visitor is better informed and prefer destinations with ecological, ethical, and social values. Some of today's tourists want to differentiate themselves from mass tourists, although authors such as Urry and Larsen or Dujmovic and Vitasovic argue that postmodern tourism also has its shadows, such as experiential travel with excessive cultural simulations. Nevertheless, tourists in general have become more demanding and there has been an increase in the creation of new services based on emotions and cultural and landscape experiences [12,13]. In this sense, it is important to identify, analyze and enjoy the benefits of educational potential of this multidimensional phenomenon, in the formation of sensitive citizens aware of the role of the cultural landscapes as something inherent to the well-being and individual and collective identity. With cultural tourism the public can understand the environmental processes, appreciate the different aspects intervening in the history of the local community visited, and demand products and services that require the conservation and management of heritage sites [14,15].

It has been shown that cultural tourism brings potential benefits to other sectors of activity [10]. Direct profits may go to companies presenting heritage to the public (e.g., communications, engineering, and design) and indirect benefits to those that take advantage of the presence of public enjoying leisure activities (e.g., hospitality, fashion, and design), and these will, at the end of the line, revert to the conservation of the heritage and landscapes they depend on. Among the benefits of the link between heritage tourism and local development, two groups may be distinguished: a priori benefits, among which are the creation of employment, increased profits, and improved training of stakeholders. Ultimately, benefits include an improvement in quality of life, a better-quality cultural tourism, enhanced social inclusion, and stronger local development [10]. One important benefit of heritage tourism is the preservation of the landscape that host(-ed) the heritage assets in question. Whatever the activity (agriculture, mining, industry, etc.), the public will be able to gain a better insight if the landscape can be "read". In the case of operating salinas, the heritage will be alive. Hence, from a paradigm of "What can heritage do for tourism?" we have moved on to "What can tourism to for heritage?" [16].

Cultural tourism may favor sites with sensitivity toward their heritage and that actively contribute to its conservation [17]. Visitors also want to actively participate in the experience, engaging in "creative tourism", that is, becoming producers of their own consumer goods and services on site [18]. The global economic crisis and later the pandemic have spurred an upsurge of so-called slow travelers, characterized by travels within the region, especially to rural areas, the search for wellness and health, and short breaks and day trips [19–23]. An important motivation found in slow travelers is the quest for meaningful and participatory experiences rather than for witnessing people and places passively [18,24]. Cultural tourism is no longer just an activity that presents artifacts to tourists, but one that takes into account the relationship between the visitor and the heritage presented, especially when including intangible heritage, which in turn helps visitors get "emotionally involved" in a "heritage experience" [18,25,26]

Salinas epitomize the complexity of cultural landscapes in which human, cultural, and natural features are intimately linked and are mutually dependent for achieving and maintaining sustainability. In addition, salinas are or can be living landscapes without the need to change them into surrogate or fossilized "heritagescapes". This strength of salinas has also been its weakness. The built heritage in salinas is pragmatic, modest, and, because of the materials used, easily degraded, hence not attracting the attention of architects and other heritage specialists. Unfortunately, changes in society and history in the past decades or even centuries have motivated the disappearance of numerous salt-making sites worldwide. A loss of around 90% has been registered [27]. By all measures, this is a serious threat to the remaining sites. Those that have not been transformed into industrial saltworks (e.g., roughly half of the remaining coastal sites in Spain) are under threat of abandonment. Hueso-Kortekaas presents an extensive review of the fate of Spanish and European salinas [27,28].

This research as a threefold goal: first, to characterize the patrimonialization process of four well-managed saltscapes across Europe. This process describes the gradual transformation of a resource-based productive activity (in this case, salt), usually in decline, into a multifunctional landscape with a heritage-based economic activity. Typically, the first stage patrimonialization takes place after the abandonment or irreversible decline of the production of salt and is then activated by interested stakeholders, usually NGOs or public administrations. After activation follows a stage of professionalization, in which the heritage asset or landscape is taken care of by individuals or organizations that have expertise in the topic, although still somewhat patchy. This stage merges onto the consolidation of the process in which a specific, dedicated entity is created and a budget is allotted for the conservation, promotion and use of the site. This is the optimal stage from the point of view of patrimonialization, as it provides stability and a strategic long-term vision [27].

The sites have been selected upon the basis of their heritage values (all of them enjoy a certain degree of protection and have a relevant historical background) and their dedicated heritage management, which consolidates their success in the transition from saltscapes in decline to complex geoheritage sites with a multifunctional character (production of salt, tourism, wellness, and education). Second, common features are sought by means of looking at the lessons learnt in the patrimonialization process, and a simplified spatial SWOT analysis is performed. Third, the work aims at extrapolating the results to other saltscapes and similar forms of geoheritage, which may contribute to better-targeted efforts and more efficient results in the protection and valuation of other saltscapes and geoheritage in general. This paper is organized as follows. Section 2 introduces the data collection techniques and SWOT analysis methods used in the study, before Section 3 exposes the results. Finally, in Section 4, the results are discussed and some ideas for future work explained.

#### **2. Materials and Methods**

#### *2.1. Selection of Study Sites*

Four study sites were chosen, namely Valle Salado de Añana in Spain, Marais salants de Guérande in France, Seˇcovlje soline in Slovenia, and the Læsø saltworks in Denmark (Table 1). The selection of all cases responds to one criterion: that is, whether they are or have been in the process of patrimonialization. This means that the selected sites do not only produce salt, but also have other areas of economic activity focused on the public: tourism, health services, or educational activities. They harbor significant heritage values, which are acknowledged by different instruments of legal protection of natural and/or cultural assets, and count with a relevant historical background at regional and national level. These are sites also known for their successful management of the artisanal saltmaking activity in a balanced combination with the protection of natural and cultural values, as well as the provision of a livelihood for the local community. The cases selected also have in common that the patrimonialization process is found in an advanced stage and can serve as an example or paradigm for others. In addition, these sites produce salt by traditional methods, reinforcing the idea of heritage conservation and transmission. The four areas are thriving examples of heritage recovery at a regional level and are well known on an international scope. Having said this, the sites differ considerably from each other in their past and recent history and how the process is driven. There are more cases in Europe and elsewhere, but their diversity of patrimonialization processes showcases different possible pathways to success.


**Table 1.** Description of case study sites according to different criteria. Own elaboration.

#### *2.2. Bibliographic Survey*

An important part of the work relied on the consultation of written literature. The sources covered both scientific as non-scientific literature. The search has been, therefore, eclectic by nature (from systematic key-word use in Google Scholar and Google News to the websites of the companies or organizations in charge of the sites, including cross references from any written document or oral referral). Google Scholar was preferred above other scientific portals because it also provides references to grey literature, which is very relevant in this context. The latter include unpublished reports, plans, and projects or internal documents and have usually been published by non-profit organizations and authorities.

#### *2.3. Interviews with Stakeholders*

Understanding local development around a saltscape (or any other form of landscapebased heritage) requires the appropriate identification of stakeholders. Stakeholders are any person or organization that feels affected by any event related to this form of heritage or landscape.

The main challenge of this part of the research has been finding the right stakeholders in each of the study sites, given the variety of roles and profiles [29,30]. They are organized or not in formal, known structures, or may be informal opinion leaders without apparent filiation. Some of them may have the right information, but not the capacity or willingness to participate in the research [11]. Stakeholders who have been relevant in the recent past but are now disengaged from the site have also been considered, especially those who have inspired or triggered management practices that have been used for some time or still are. The main method to find stakeholders in the field was the snowball, by which first-level contacts provided new contacts that were deemed relevant in the context of this work.

Interviews have been performed with 10–12 key stakeholders per site in relation to past, present, and future plans and projects in the study sites involved. Their roles included owners and managers of the salinas, local public administrations, tourism authorities and businesses, (nature) guides, academics and scholars, spa and wellness managers, and, of course, salt makers.

The interviews were semi-structured. The reasons to choose this format were threefold [31]. First, the situations tackled were very different between and even within sites, which required flexibility in the design and development of the interview.

Second, the information needed was rather complex and the responses were expected to differ significantly, both in tone and in content, depending on the stakeholder involved. Third, the need to create a relaxed atmosphere, especially in group settings or with biased stakeholders, recommended this user-friendly format.

#### *2.4. Field Visits and Observations*

The field visits were intended to observe first-hand the state of the salt-making site and the surrounding landscape, to visit the businesses and other facilities associated to salt, and to perform the interviews with local stakeholders. Direct observation allowed us to improve the understanding of the site, the decisions of its owners or managers, and the relations among stakeholders. The field visits provided an opportunity to register the most relevant features and significant events related to or resulting from the management of the salt-making site and also a holistic, integrated view of its hinterland.

#### *2.5. Spatial SWOT Analysis*

To understand the current situation of artisanal salinas and how they face the future, it is important to have a deep knowledge of them and of their hinterland. Spatial SWOT analysis is a method frequently used to elaborate on strategic territorial diagnoses and make decisions. The SWOT is a classic analysis tool for strategic management enterprise proposed by Kenneth Andrews (1971) [32] that has been transferred to territorial planning and cultural management. Spatial SWOT analysis plays a dual role. It fills in the gap of scientific knowledge and local data and is an approach that synthesizes the information collected through different sources [33–35].

Its name comes from the four ideas that it focuses on: strengths, weaknesses, opportunities, and threats. The items "strengths" and "weaknesses" refer to the current intrinsic aspects of the sites, whereas the items "opportunities" and "threats" are related to their sociocultural and business environment and typically hint at situations that will arise in the future. SWOT is an appropriate diagnostic and evaluation tool to obtain an initial idea of the state of the saltscapes and their possible future evolution. The benefit of this method is its simplicity. Moreover, it is user friendly and does not require computer systems or software [36,37].

In this work, the SWOT matrix analyzes the internal strengths and weaknesses, as well as external threats and opportunities, to guide the future expected strategies. The objective of this matrix is to determine all applicable strategies. First, by using the internal strengths we attempt to exploit the external opportunities and maximizes them. Second, using the present opportunities in the internal environment we attempt to improve weaknesses. Third, using the strengths counteracts the effects of current threats and, fourth, the internal weaknesses are minimized and threats caused by the external environment are prevented.

#### **3. Results**

#### *3.1. The Values of Saltscapes*

Common salt (NaCl) is an essential constituent for living beings. It is found in nature in the form of rock salt in layers at different depths of the Earth's surface; or dissolved in surface water and groundwater (oceans, lakes, springs, or saline aquifers). Sea waters contain an average of 35 g of salt in solution per liter, which varies between warmer seas such as the Mediterranean and the Red Sea, which have a salinity of 37 and more than 40 g per liter, respectively, and colder seas such as the Baltic, which barely reach 10 g of salt per liter of water. In the case of salt sources, the circulation of water between salt deposits dissolves and transports the salt in solution over long distances in saline aquifers until it reaches the surface, sometimes reaching salinities of over 200 g of salt per liter.

Halophile vegetation absorbs NaCl in solution and incorporates it into the food chain. Wildlife and humans consume vegetables and other animals, incorporating salt into their diet. However, that being insufficient, they collect brackish water or lick rock salt, because salt is essential for their survival. It has specific functions in each of the metabolic cycles and in cellular nutrition. Our body has no reserves of sodium chloride, so it must constantly regulate the amount of salt present through the kidneys and urine [38].

But in addition to the importance of sodium chloride at an organic level, we cannot ignore all the culture that has been generated around its use: food, therapeutics, salting, preservation of skins, industry, religious rites, etc. This is the reason why salt, together with cereals and wine, was considered the basic trilogy of the Mediterranean economy from antiquity until practically the 20th century. Since Neolithic times, humans have collected salt for a variety of purposes. Salt production, trade, and use are at the basis of the so-called saltscapes: environmentally unique sites with a very powerful historical, cultural, and symbolic significance. Therefore, the historical value of salt has left its imprint on the territory and on culture: the salinas themselves, but also trade relations, taxes, byproducts, etc. The salinas have allowed a social and ecological coexistence by reconciling the exploitation and sustainable use of the territory. They have contributed to human supply and environmental heterogeneity, and increased biological diversity, playing a key role at the ecological, anthropological, landscape, socio-economic, and cultural levels [39]. Saline water generates ecosystems with special features. They are wetlands in which salinity acts as a limiting factor. However, the organisms that occupy these fragile and unique ecosystems serve as food for many species of birds that nest and rest in them. When humans develop an economic activity to produce salt, environmental and landscape conditions are modified. The surface area occupied by brackish water increases and a semi-industrial architecture is created (ponds, pools, threshing floors, canals, roads, warehouses, etc.) with ecological, cultural, and heritage implications. Saltpans become habitats for organisms that thrive in a range of extreme salinity, temperature, pH, nutrient concentration, oxygen availability, and solar radiation. The production process involves increasing the concentration of salt in the water until it becomes brine. As salinity increases, some organisms are replaced by others: halophilic micro-organisms, including bacteria, archaea, and fungi, which are important in the biogeochemical functioning of salinas [40,41]. Halophilic algae incorporate energy into the system, feeding crustaceans such as *Artemia* sp., which in turn feed the birds [42], making the salt pans important sites for various species of flora and fauna.

However, it should not be forgotten that these unique habitats have their origin in a productive anthropic activity, which began with the collection of salt precipitated in the hollows of coastal rocks or in the beds of salty rivers, and which has evolved into the construction of semi-industrial facilities. The geographical features of a territory are determinant in salt production [43,44]. Therefore, the production process involves knowledge of the environmental processes and the construction of an infrastructure for the management of salt water. The salinas are made up of a set of shallow artificial ponds at different topographical levels, to which seawater or water from saline springs is transported by means of a network of canals. The salt is obtained in these ponds after a first concentration stage and a second crystallization stage.

The physical process of the evaporation of brackish water requires an external energy source that increases the temperature of the water to the point where the dissolved salts begin to precipitate, forming salt crystals. The latitude and location provide favorable climatic characteristics (high annual sunshine and low rainfall during the harvesting season; winds to accelerate evaporation) so that salt production depends exclusively on the use of direct solar energy [45,46]. In sites where climatic conditions are not suitable for solar evaporation, the alternative has been to induce brine evaporation by a wood combustion process. On the other hand, the topographical characteristics are relevant in its location, since it is a process that requires important extensions of land on which to build the evaporation ponds.

Obtaining salt does not depend only on the production infrastructure. The experience and know-how of the salt makers has also been relevant when it comes to achieving greater production and higher levels of purity in the salt (NaCl). Sodium chloride is not the only salt present in the water. The construction of a succession of ponds of different depths and at different elevations makes it possible, on the one hand, to saturate the water, converting it into a brine, and on the other to precipitate—in the first set of ponds—other salts that are less soluble than sodium chloride, such as CaCO3 or CaSO4, which are present in the water. Finally, the practically saturated brine (25.7 ◦Baumé) is redistributed to the crystallizers. These are square or rectangular ponds, no more than 15 centimeters deep and with a flat bottom, also known as saltpans, where NaCl precipitates at 28–29 ◦Baumé.

In both coastal and inland salinas, the production process does not end with the crystallization of sodium chloride. Once the NaCl has precipitated, the brine contains other more soluble salts, so the water can be reused to obtain sodium and magnesium sulphates, which are used in the glass and soap industries or in cosmetics, respectively. Finally, the salt itself must be accumulated, dried, and protected from possible inclement weather. Thus, a building linked to the salt installation is needed: the warehouse, where the tools of the salt workers were also kept.

In some inland areas, the abrupt relief makes it almost impossible to have flat surfaces to build the crystallizers. To make up for this lack of horizontality, a system of artificial terraces is set up on the slopes, based on stone and wood structures. The upper part of the terraces is used as a saltpan, while the space between the embankment and the structure is used to store the extracted salt. A salina is therefore a natural, scenic, and cultural heritage that demonstrates the human use of geological resources and shows the intimate relationship between humans and nature that goes beyond the sheer extraction of a raw material.

According to Quesada and Malpica, the production of salt in the salinas resembles an agricultural process because, first, the land must be conditioned and transformed as if it were cultivated fields. As in agriculture, it is necessary to build structures (terraces, banks, and pipelines). Second, there is an assimilation of hydraulism, as found in irrigated agriculture. Water management is typically based on four pillars: catchment, transport, storage, and distribution. Third, it does not require a complex infrastructure, nor investment in manpower or their training because expertise is acquired with practice. Fourth, an idea of "harvesting" is generated from the use and management of natural resources [45–47]. Having made this analogy, it is important to highlight not only the ecosystem services

offered by salinas, but also the economic and cultural ones. They are productive cultural landscapes with multiple values, so they must be managed in terms of conservation of geological and geomorphic processes, conservation of biological processes, production of goods, and production of tourist and educational services [48,49].

#### *3.2. Landscape and Geoheritage Characterization of Study Cases*

Each case study has, as expected, unique features and narratives. In this section, a brief description, and a summary of the recent history of each site is provided, in relation to its patrimonialization process. Table 2 summarizes the main features of the patrimonialization process of each site. However, patterns can be found with respect to these processes that allow the identification of strengths and weaknesses, as well as lessons taught, for saltscapes and salt heritage in general. These are offered at the end of this section.

**Table 2.** Main features of the four study sites. Own elaboration.


#### 3.2.1. Valle Salado de Añana (Basque Country, Spain)

The cultural landscape of Valle Salado de Añana (42◦48 N, 2◦59 W, 531 m a.s.l) is located in the southwest of the Basque Autonomous Region. The salinas lie in a deep Y-shaped valley formed by the River Muera (brine, in Spanish) and occupy a surface of ca 10 hectares (Figure 1). Brine is obtained from wells that tap groundwater that has been in contact with the diapir just below. The brine is then distributed via aerial wooden carved channels to the crystallizers located in wooden terraces built on the slopes. The origin of the saline aquifer lies in the presence of a diapiric structure derived from the intrusion and tectonic uplift of evaporite rocks dating from the Triassic period—facies Keuper (salts, gypsums, and clays) through denser materials [50]. When surface runoff waters infiltrate and circulate through these materials, they are loaded with salts and become brackish or brine. These brackish waters arise to the surface in the form of saline springs. From there, the brine, which flows with a salinity level of 210–240 gr/L, is conducted by gravity through channels toward the crystallization pans, which are arranged in terraces on the slopes of the valley. Once the brine is distributed over the saltpans, the sun evaporates the water and salt crystallizes, just as in other solar evaporation salinas. The geological origin of the salt and the geomorphology of the valley explain the uniqueness of this landscape from an environmental perspective [50,51].

Salt making in the area has been documented from the year 822 C.E., but recent archaeological research has found evidence of salt-making activity as early as 7000 B.C.E. [52]. The saltworks flourished in medieval times, under the control of the salt workers-cumowners organization known as the Community of Heirs. As occurred with many other salinas in Spain, in 1564, under King Philip II, they became state-owned during a prolonged period. In 1869, the Community of Heirs recovered the power over the management of the salinas and the traditional salt-making methods they had been using in the past. Due to competition from other salinas, productivity was being increased by irrationally enlarging the surface of crystallizers, building them on dangerously steep slopes, above the level of the sources or using new materials that proved useless, such as concrete. The latter caused major damage to the wooden structures and pollution from debris in the valley. Despite these modernization efforts, salt was still being harvested by hand [53].

**Figure 1.** Maps of the study area and location of the Valle Salado de Añana (Spain). The perimeter of the salina is delimited in red. Source: Own elaboration.

In 1960, the valley had about 5000 crystallizers in operation, which went down to 150 in 2000. Production decreased from 4000 tons to hardly 3. In the years 1999–2000, the salinas were practically inactive [54–57]. The Valle Salado was declared a BIC (Good of Cultural Interest, in its Spanish acronym) in 1984 with the category of Monument. The Diputación Foral de Álava (provincial administration) initiated a series of actions to recover the valley. In the years 1998 and 1999 the Comunidad de Herederos de las Reales Salinas de Añana (Community of Heirs) became a private company, the Sociedad de Salineros Gatzagak, S.L., which gathered all the owners of the crystallizers. With a contemporary legal structure, the ownership became unified, and third parties had one single representative to address, thereby facilitating the recovery of the valley. In 2009, the Fundación Valle Salado (Valle Salado Trust) was founded, its trustees being the provincial government, the Basque regional government, the municipality of Salinas de Añana, and the Company Gatzagak S.L.

A 20-year Master Plan with a budget of EUR 20 million was devised, setting the physical limits of the monument in order to better determine its functional and landscape recovery and to organize the management and activities of the salinas and its environment to enhance its use and enjoyment by all [58–60]. With the turn of the century, the first measures to create public access to the salina were taken (Figure 2). The public was invited to visit the works, under the motto "Open for repairs". The visitor program of Añana is an ever-growing activity, with ca 100,000 annual visitors in the last decade. The tourism offers range from regular guided tours to specialized tours for schools or special interest groups. Visitors can also book brine foot or hand baths and soon a flotarium will be available.

**Figure 2.** View of some of the restored saltpans and channels in the Salado valley of Añana. This section can be visited on guided tours only. Own elaboration.

The informants generally agree that the project has brought significant benefits to the village, aside from visibility and local pride. The initial stages of the patrimonialization process were difficult, as stakeholders needed to find a common ground to agree upon and the top-down approach did not contribute to motivate the local community.

#### 3.2.2. Marais Salants de Guérande (Bretagne, France)

The Guérande salt marshes (47◦17 N, 2◦27 W, 0 m a.s.l.) are located in the southern half of Brittany (France) between the mouths of the rivers Loire and Vilaine, facing the Atlantic Ocean. They form a very large wetland zone in western Loire-Atlantique and occupy a surface of 2000 ha (Figure 3) [61]. The current relief is the result of the razing of the Hercynian mountains, the fracturing in inclined blocks, of the post-Hercynian razing surface during the Cenozoic, and of differential coastal erosion during the last marine transgression. The geographical area has a lithological variety typical of geological history (Brioverian schists, gneiss, granite, migmatites, and Quaternary sediments) [62]. The disposition of the inclined blocks of Le Croisic-Batz and Guérande, as well as that of the isthmuses of Pen-Bron and La Baule, have created the conditions for the formation of a maritime marsh, whose clogging by sand and mud intensifies toward the base of the slope of Guérande (where it is more than 20 m thick) [61–63].

Salt has been harvested on the peninsula since the Iron Age. The first saltworks to use the storage capacity of the lagoon goes back to the 3rd century, shortly after the Roman conquest. The first salt marshes as are known today were shaped by the monks from Landévennec Abbey, who, in 945, carved them out by studying the tides, wind, and sun. The salinas brought prosperity to Guérande for many centuries and opened the first trading routes in Europe. Today, at least five saltworks from the Carolingian period are still in operation. After a period in the mid-20th century when the salinas were threatened with urban sprawl, certain sectors of civil society sensitive to the cultural and natural values of the site managed to reverse this threat and recover the salt marshes as they had always been. A key issue in the empowering of salt makers was the strong union formed by the

different stakeholders that fought the development plans in the early 1970s, including Breton nationalists and environmentalists. This formed the seed of a strong social and political awareness in the area, that has now grown to become a solid, well-organized supporting tissue in the region [30,64].

**Figure 3.** Maps of the study area and location of the Marais salants de Guérande (France). The perimeter of the salina is delimited in red. Source: Own elaboration.

The decade of 1975 to 1985 was characterized by the reconstruction of the salt-making activity and the recovery of the marshes (Figure 4). The main challenge was to find replacements for the ageing salt makers, as few young people wanted to take this profession.

Thanks to the arrival of interested apprentices from other regions, the activity gradually regained momentum. Because of this interest, in 1979, a training center for young salt makers was opened. The tradition of the salt worker's profession was thus recovered, and the preservation of these skills have allowed the Guérande marshes to survive through to modern times. Today, about 16,000 tons of coarse salt and 700 tons of *fleur de sel* are produced each year.

The public interest in hand-harvested (as opposed to industrial) salt was gaining strength and so did the tourism pressure in the area. Salt makers still saw tourism as the main threat to their livelihood but slowly started to see visitors as partners rather than enemies in their quest to defend their profession and their landscape. The relationship between salt makers and visitors gradually improved over time and the creation of the visitor center Terre de Sel further contributed to regulate and ease the previous tensions between them [64]. It organizes thematic guided visits, also catering to school groups. Two other museums exist around the world of salt making in the neighboring locations of Batz-sur-Mer (Musée des Marais Salants) and Saillé (Maison des Paludiers), the three of them receiving more than 130,000 visitors annually. Today, the area of La Baule–Presqu'ile de Guérande has a well-developed tourism industry. Guérande receives 1.2 million visitors per year. It is calculated that one-fifth of the revenues generated in the area are related to tourism and more than 8100 people are employed in this sector [63,65].

**Figure 4.** Winter view of the salt pans of one productive unit in the marshes of Guérande. These pans will be cleaned before the next salt making season. Own elaboration.

The informants generally present positive feelings about the patrimonialization process, which was initially rough. However, there remain some differences in the focus, as some *paludiers* believe the essence of the site is being lost because of the commodification of the salt itself and the concept of *fleur de sel* in particular. In fact, some salt masters do not wish to belong to the cooperative for this reason (*G.P., pers. comm*.). On the other hand, nature conservationists perceive a pressure to recover more surface for salt production and feel it will cause a detrimental effect on habitats and birds (*D.M., pers. comm*.). In such a large site, striking the right balance seems difficult.

#### 3.2.3. Læsø Saltworks (North Jutland, Denmark)

The Læsø saltworks (57◦15 N, 11◦2 W, 0 m a.s.l.) are located in the southeast of the island of Læsø in northernmost Denmark (Figure 5). As Jørgensen explains, the area is the marine foreland composed of four minor low islands, a belt of coastal meadows and salt marshes and wide areas of sand in shallow water [66]. The terrain is practically flat (low altitude and minimal slope) and the existing vegetation depends on the seawater level. From the inner part toward the coast, the meadows gradually transition into salt marshes. The geology present in the area is composed of a thin cover of sands and silts intertwined by layers of sands and coarse gravels. Beneath these materials is interglacial marine stiff clay [66,67]. The saline water to produce brine and salt is captured from the aquifer formed by post-glacial marine sediments, which has salinity percentages above 17%.

Salt is being produced by seething, using wood as fuel. The brine is pumped from the salty water table of Rønnerne, in the nearby sandbanks of the southern edge of the island. This brine is twice, or three times as concentrated as seawater and is collected in wells to be further concentrated. The brine is then boiled or seethed to obtain a product of high-quality, equal to the famous salt from Lüneburg in Germany.

**Figure 5.** Maps of the study area and location of the Læsø saltworks (Denmark). The perimeter of the salina is delimited in red. Source: Own elaboration.

In the Middle Ages the Læsø saltworks were the most important workplace of the island and were considered the first industry of the time. Salt production stopped in 1652 because seething salt in the huts required large amounts of biomass. By then, the salt industry had used up all the fuel wood on the island and the island was transformed into a windswept desert. The ruins of the old huts where the salt was boiled are still standing as low, square embankments. There are an estimated 1000 of them on the island.

Archaeological research in the mid-20th century revealed how salt making was done a few centuries ago. From the results of the excavations in 1990 it was decided that the Municipality of Læsø would rebuild a salt seething hut, originally with an educational purpose. The goal of the project was partly to put Læsø on the map by telling its unique story about salt, and partly to contribute to the archaeological knowledge on seething by restarting the salt-making activity on the island according to 16th century methods [68–71]. Initially supported by the public authorities, it quickly grew into a thriving productive activity with a keen interest from visitors.

It was soon decided that the visits should be free of charge. In exchange, the salt was sold at a high price, but that was justified as a support to cover the costs of the project. In the first years, the usual high costs derived from salaries were cut because of the participation of the school workshop of the island, whose employees were hired to work in the huts. Læsø Saltworks uses between 1000–1500 cubic meters of firewood every year, less than 10% of the current harvest of forest products, well below the limit of sustainability. Today the salt making activity is highly organized and successful.

The saltworks are making an important contribution to the economy of Læsø. As a tourist attraction, the saltworks receive more than 60,000 visitors per year, half of the total amount of visitors to the island. The saltworks produce ca. 70 tons of salt per year, selling both locally and all over Scandinavia. The salt is highly valued by customers and visitors and has become a culinary reference in high-end restaurants in the region. The new saltworks were never conceived as a museum, even though its main revenues come from tourism (Figure 6). Visits are still free of charge, because the site is considered a living place of production, in full operation and visitors come for the experience [72].

**Figure 6.** Restored salt-making hut in the saltworks of Læsø, according to the findings of the archaeological excavations conducted in 1990. Own elaborate.

Perhaps the single most relevant new business associated with salt is the thalassotherapy center, Læsø Kur, which opened in 2008 in a deconsecrated church. In just over 1 year, the center offered numerous therapy services (sauna, steam bath, cool water pool, mother lay baths, jacuzzi, and massage), leisure, and beauty treatments. The center has an agreement with the Danish health system to offer packages for patients and, of course, anyone interested can purchase their own wellness or therapy packages.

All informants agree upon the benefits of the patrimonialization process and do not manifest critical views of it. It seems to have had a net positive impact on the economy of the island, also beyond the salt-making and tourism activities themselves (*B.B., P.C., P.S. pers. comm.*). Some initiatives did not survive (e.g., a salt-themed restaurant), but generally speaking there is a broad consensus about the success of the process.

#### 3.2.4. Secovlje Soline (Istria, Slovenia)

The Seˇcovlje salt pans (45◦29 N, 13◦36 E, 0 m a.s.l.) are located in the southwest part of Slovenia, (Gulf of Trieste, northern Adriatic), next to the border with the Republic of Croatia, on the Istria Peninsula. The Slovenian coast, albeit short, is highly varied. There are cliffs, shingle beaches, and coastal plains (lagoons and wetlands). This last type of coast is the result of the accumulation of large quantities of fine sediments, deposited by the Soca, Rizana, Badasevica, and Dragonja rivers, facing a shallow sea with a shelving sea bottom. The Slovenian coast evolved in the Holocene. Vahtar explains that the valleys have been transformed into bays, with alluvial sediment deposition still ongoing, while ridges changed into peninsulas developing cliffs at the coastline [73]. The rock materials are Eocene flysch, while in the plains, fine-grained alluvial sediments predominate. The Seˇcovlje salina is a coastal marsh wetland developed on a sedimentary plain of the Dragonja River [73,74]. It consists of two parts. Its northern section, where salt is still being actively produced and harvested, is known as Lera. The southern section, called Fontanigge, is separated by the Grande–Drnica channel (Figure 7).

**Figure 7.** Maps of the study area and location of the Secovlje soline (Slovenia). The perimeter of the salina is delimited in red. Source: Own elaboration.

The Seˇcovlje salinas are today the largest coastal marsh wetlands (650 ha) in the country, and at the same time the most important Slovenian locality from the ornithological point of view. Today, 272 bird species have been found in the salinas, with some 90 breeders among them. Based on these facts, the Government of the Republic of Slovenia in the year 2001 declared the Seˇcovlje Salina Natural Park and the adjacent Museum of Salt-making as a cultural monument of national importance. In 1993, the salinas became the first Slovene wetland, inscribed on the list of internationally important marshes under the auspices of the Ramsar Convention. The salina represents different ecosystems, from marine to brackish, fresh water and land ecosystems.

The traditional manual harvesting of salt in these salinas, over 700 years old, is a representative feature of the cultural heritage of Mediterranean Slovenia. Until the beginning of the 20th century, the saltworks were owned by wealthy families, churches, monasteries, and charitable institutions. The salt worker was merely the tenant of the salt field and the producer of the salt. The golden age of salt making in Seˇcovlje lasted from the 15th century to the end of the 18th century, under the control of the Venetian Republic [75]. In 2000, the Seˇcovlje Salinas Nature Park was designated the first protected area in Slovenia when the concession for its management had been given to a business company (SOLINE Pridelava soli d.o.o.), which is owned by the national biggest phone company (Mobitel d.d.). The company is responsible for the management of the state-designated Nature Park and use of its natural resources. The company also is responsible for the protection of nature in the state-owned property of the Seˇcovlje Salina Nature Park. In return, the Republic of Slovenia provides funding for the management of the protected area [76]. The park receives 30,000 to 45,000 visitors per year, mainly during the summer [77]. Their salt is well known in the Eastern Mediterranean and the site constitutes an example of good management practices and smooth transition from a communist to a capitalist economic system.

In general, the informants agree that the saltworks have a positive influence on the local economy, although there seems to be certain lack of coordination between stakeholders. There are pending issues, such as the access to the salt museum in the border between Croatia and Slovenia, or the management of visitors to the protected area within the productive area of Lera (*F.B. and D.C., pers. comm.*).

At the turn of the millenium, 593 ha of salt-making surface were recovered in Fontanigge (only for the provision of brine) and in Lera (for the whole salt-making process, which accounted for 25 salt-making units). In 2002, 18 men were employed who produced 100 tons of salt. A decade later, more than 94 hired workers produce up to 5000 tons of salt and 30 tons of *fleur de sel* per year (Figure 8). In 2013, the company SOLINE Pridelava d.o.o. decided to invest in a thalassotherapy center to take advantage of the two subproducts of salt making with healing properties, namely the mud (also known as *fango* or peloid) and the mother lay or *acqua madre*. The complex, named Lepa Vida, was built within the natural protected area and has a total surface of 4000 square meters.

**Figure 8.** Salt worker harvesting salt in Lera, according to methods used in the salinas of the Adriatic basin in the 15th century onwards. Own elaboration.

#### *3.3. Common Features of the Patrimonialization Processes of the Four Study Sites*

The four study sites can be considered consolidated examples of patrimonialization and sound use of geoheritage. Despite their differences in ownership, management, heritage assets, and funding, they share some common features that may be contributing to their success. All four sites have some form of protection status, some more diverse, including both natural and cultural values (Añana, Guérande), than others that focus on the natural aspects (Seˇcovlje, Læsø). From the point of view of management, the four sites count with a specific, dedicated entity: the Valle Salado Trust in Añana, the Cooperative de Salines de Guérande in Guérande, the company Læsø Salt in Læsø, and the company Soline Pridelava in the case of Seˇcovlje. These entities oversee the management, financing and long-term strategies for the protection of geoheritage, education, and tourism in their respective locations. They are all but financially self-sufficient, with gradually decreasing government support in the cases of Añana and Seˇcovlje and none in Guérande or Læsø. In all cases, albeit with slight differences in priorities, they form multifunctional landscapes with a focus on four aspects: artisanal salt making, tourism, education, and wellness products and services. At this point in their geoheritage development and use, two risks need to be taken care of.

On the one hand, these entities are dependent on income and need to devise mechanisms to secure financing. To this end, the initial priority to protect and educate about their heritage may shift to a more commercial one. As the protagonist role of the stakeholders involved in the early stages of patrimonialization fades, the new managers may lose this initial perspective. Examples of the banalization of this geoheritage are the organization of mass events such as mountain races (e.g., in Añana, which to be fair was held only once) or the export of artisanal salt to places where this heritage is unknown (especially in Guérande and Læsø), thereby counteracting the discourse of local identity and heritage. This effect is under further stress because of competition from industrial saltworks across the Mediterranean region, which now use a narrative and aesthetics that imitate artisanal salt-making. Consolidated artisanal salt-making sites need to constantly shift their discourse to distinguish themselves from such imitators.

#### *3.4. Saltscapes' Spatial SWOT Analysis*

Table 3 summarizes the main strengths, weaknesses, opportunities, and threats of studied saltscapes. From the point of view of the structural strengths, as compared with other productive activities, salt is a well-known commodity that may trigger the interest of a broad sector of the public. These landscapes provide a harmonious and serene combination of natural and artificial elements, in which water is protagonist. The apparent simplicity of the structure of the wetland allows easy reading and understanding, especially if there are recent remains of the activity. Since these sites have been traditionally isolated, they have not often been visited prior to their use as tourism and educational assets. The members of the public who seek new, rewarding sensorial experiences can find them in (former) salt-making sites.

Saltscapes are usually located in rural areas, which are experiencing an ever-growing appreciation of their culture, as a token of authenticity and a return to one's roots. The local community, on the other hand, shows a pride in their traditions, practices, and products, with a stronger sense of belonging to the area. Salt has the advantage of being a universal, everyday item. It is therefore relatively easy to raise the interest of the public in it.

There are numerous protection and planning instruments available that can be applied to the management of these sites. Given the multifunctionality of saltscapes, the variety of instruments is one of the largest possible. All this will also increase the chances to obtain public investments, although the global economic crisis is hitting hard, especially in the socio-cultural and environmental sectors. Perhaps the strongest and most specific strength of saltscapes is that they can be recovered for the original purpose they were made for. This is not common in former industrial or mining sites and happens only occasionally in certain rural activities such as bakeries, lime kilns, or charcoal-from-biomass.


**Table 3.** SWOT analysis of salt heritage and saltscapes.

The main structural weaknesses of saltscapes have to do with location and technology. Salt can only be made where certain geological, climatic, and topographical conditions exist. Salt making itself is a strenuous activity that requires a young, fit, and motivated workforce. Bearing in mind that salt can only be harvested a couple of months per year, salt workers need to combine this job with other activities. The maintenance of salinas is also demanding, especially those that had some importance in the past, which host more complex infrastructures, a larger productive surface, plus housing, offices, and several warehouses. These sites are especially vulnerable to climate change, not only in terms of flooding (if at the coast), but also because of their intimate dependence on functional natural processes [78]. Delays in planning and performing recovery activities rapidly increase the costs, and maintenance after that is very costly in terms of manpower.

From the point of view of management, salt making is not a priority activity for authorities and institutions that may provide (financial) support, such as rural development agencies or chambers of commerce. The little institutional willingness to invest in these facilities is usually aggravated when the sites are in private hands. Planning and implementing recovery projects in these sites is costly and the global economic crisis has significantly decreased the funding opportunities for the upkeep and rehabilitation of rural heritage, both from public as from private bodies.

Nevertheless, the increasing sensitivity toward sustainable tourism initiatives may benefit tourism around saltscapes, as the sites lend themselves well to a slow, conscious, experience-based form of tourism [79]. There are also numerous potential uses of a saltscape that are compatible with the conservation of their natural, cultural, and human values. They may even lend themselves to new economic activities around research, innovation, and development and commercialization of by-products. There is also a growing flexibility in funding practices that do not require strong investments. As well, authorities seem to be more open to transfer tasks to private organizations, e.g., with land stewardship agreements, volunteer work, etc., making the management of the sites more diverse. This enhanced flexibility is also perceived in society in general, with a growing diversity of products and services, where the traditional dichotomies client-customer, resident-visitor, or student-teacher, to name a few, are becoming blurred. Also, synergies with other heritage assets or like-minded initiatives in the area can be found. The diversification of activities increases the opportunities of participation for the local community, thereby empowering

them around their heritage. All this may create unimaginable synergies and collaborations that may provide new opportunities for heritage to (re-) emerge. Hence, despite the gloomy economic scenario, it may become an opportunity rather than a threat.

#### **4. Discussion and Conclusions**

Salinas and saltscapes are geoheritage sites whose existence cannot be understood without the human use of geological resources. They are places where the economic exploitation of salt has contributed to increase their environmental and cultural values and to their legal recognition under different forms of protection. This sum of circumstances, geological processes, biodiversity, habitats, cultural heritage, landscape, etc., has led to an increase in the significance of these areas, which have become more than just a wetland or a salt production area. There is a greater identification by the local society, which demands preservation policies from public authorities. A process of patrimonialization of the site takes place with consequences on the environmental, cultural, political, and social dimensions. However, there are different circumstances that make these sites fragile enclaves, which require attention, sensitivity, and creativity in their treatment so that they can continue to fulfil their multifunctional role. There are no homogeneous measures for their management because their diversity (geographical, functional, and social) means that specific actions are required in each case. However, some lessons can be learned from patrimonialized saltscapes, which could serve as a reference for other geoheritage sites. In these cases, the importance lies in being inspired by the processes behind their patrimonialization and socio-economic valuation, rather than by the specific products and outcomes of each site.

One of the approaches being proposed is the social and economic revaluation of territorial resources and landscapes. There are various public policies that rely on cultural and natural assets as instruments for the differentiation and recognition of regions and places to be valued, as criteria on which to base the distribution of facilities, as elements for the promotion of tourism and other services, as sources of employment, and as places for learning and the creation of collective identities.

Among the factors that contribute to the patrimonialization process of geoheritage sites are the range of cultural ecosystem services they offer. These services are associated with the ecological, cultural, and symbolic valuation of the sites, in addition to the production necessary for their proper functioning. In this way, many key sites are protected and recognized for their aesthetic contributions, the beauty they inspire, the spirituality they trigger, the cultural identity they establish, the knowledge they represent, and the health, education, recreation, and tourism services they provide for human well-being. However, there is a need for greater recognition of the importance of geology and geomorphology focused on conservation, education, and sustainable development. Indeed, although geosites and their landscapes synthesize a whole set of structures and socio-environmental processes, their educational use has not received much attention in research [80], nor in outdoor teaching activities [81]. However, the interpretation of the landscape in situ, together with the use of historical events and material and immaterial cultural heritage, can facilitate the understanding of places and the learning of the environmental, socio-economic, and cultural processes that have shaped them. The importance of geo-environmental education for the promotion and preservation of geological heritage and geo-ethical values should be emphasized [4].

The value of geoheritage sites should be promoted among civil society and taken advantage of by teachers and planners—hence the need to promote them publicly, develop methods for their valuation, and define their qualities and character to establish their vocation. This is the way to achieve effective management under an appropriate legal framework [82,83] and a dedicated entity could provide stability and focus. During the last 2 decades, international networks and organizations have worked to promote binding protection of geosites (such as the Geosites project, promoted by the IUGS, or the European Geoparks Network). The states and regions have also opted for their legal recognition and regulation [84]. The protected status should not be seen as a limiting element but should serve as a catalyst for preservation and local development. Salt-making sites that have developed legal planning and management mechanisms, sometimes with publicprivate investment, eco-labels, marketing strategies, or land stewardship mechanisms, are a magnificent example. In addition to guaranteeing the preservation of the values that are at their origin, they have made possible the creation of new services and products. Geotourism stands out, which involves visits by tourists interested in consuming knowledge and products linked to the salinas, which translates into new investments, more infrastructure, businesses, and job creation that contribute to the diversification of the local economy.

**Author Contributions:** Conceptualization, K.H.-K. and E.I.-G.; methodology, K.H.-K. and E.I.-G.; software, E.I.-G.; validation, K.H.-K. and E.I.-G.; formal analysis, K.H.-K. and E.I.-G.; investigation, K.H.-K. and E.I.-G.; data curation, K.H.-K.; writing—original draft preparation, K.H.-K. and E.I.-G.; writing—review and editing, K.H.-K.; visualization, K.H.-K. and E.I.-G.; supervision, K.H.-K. and E.I.-G. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

