1. Introduction
The word and the concept of “geodiversity” was first introduced in the early nineties [
1,
2]. The term, coined as an analogue to biodiversity [
3], has become increasingly common, and it mainly appears in relation to geological heritage and conservation [
4,
5]. Nevertheless, it has not always been used with the same meaning. For [
6] geodiversity is “the number and variety of structures (sedimentary, tectonic, geological materials (minerals, rocks, fossils and soils)), that constitute the substratum in a region, above which the organic activity is settled, the anthropic included”. This definition focuses on the geological features leaving space for the possibility of the development of anthropic activities. On the other hand, [
7] considers geodiversity as the diversity of the geographical space and defines it as “the diversity coming from the nature itself (physical-geographical environment) and from the social processes, such as production, settlement and circulation (the human being and its activities)”, considering human activities (e.g., mining) as part of geodiversity. According to [
4], the question regarding whether geodiversity should be included in geographical diversity or excluded from it poses practical problems, and therefore geodiversity should be considered as an intrinsic part and a characteristic feature of the territory. As part of the territory, it would relate directly to the geography, landscape, climate, culture and economy of the area. The study of geodiversity, limited to strictly geological features (geology, topography, geomorphology, hydrogeology and soils), represents the base from which relationships between other features and the geological heritage can be developed.
The geological heritage is defined as the group of geological elements with outstanding scientific, cultural and educational values [
4,
5,
8,
9,
10]. Even though the terms “geological heritage” and “geodiversity” are related to each other and they are both subject to assessment of interest and quality, the study of geological heritage is independent from that of geodiversity. The latter does not consider the variety, frequency and distribution of geological-geomorphological features. Some authors, such as [
11], maintain that the geological heritage is a representative example of the geodiversity of a given site. Geological heritage is formed by all those places or points of geological interest, defined as sites or geosites that stand out from their surroundings due to their scientific and/or educational value.
Usually, only a small fraction of the geodiversity has a relevant value to justify the application of geoconservation measures, regardless of whether this fraction is considered geological heritage or not [
12]. According to [
13], geoconservation strategies should be applied to the characterization and management of every feature of geodiversity that shows any kind of value. A simplified conceptual framework explaining and correlating geodiversity and its main components, within the domain of natural diversity (geosites, geoheritage elements, geodiversity sites and geodiversity elements) [
12], is shown in
Figure 1.
Many governmental programs (e.g., Geoheritage-federal-programs, USA) aim to preserve the sites that are considered the most valuable in terms of their geodiversity especially if they are classified as geological heritage. These programs are generally referred to as geoconservation programs [
12,
14,
15]. The development of an inventory of geosites should be the first step of every strategy pursuing geological heritage conservation. The implementation of conservation and interpretation without a complete inventory of geosites is an inappropriate beginning for any geoconservation project [
16]. Creating a protected area is, in most of the countries, a long and complicated bureaucratic process. Thus, this effort must only be applied to those geosites, which stand out due to their scientific, academic and touristic values. To assess this importance, a sound national inventory is essential. After creating an inventory of geosites, the following steps in the geoconservation strategy must be their characterization by assessing their relevance, their protection according to the national legal framework, their preservation, interpretation, and monitoring [
12].
Another concept directly related to geologic heritage or geoheritage is “mining heritage”. It can be defined as the total surface and subsurface mining works, hydraulic and transport facilities, machinery, documents or objects related to former mining activities with a historical, cultural or social value [
17]. There are several places on the Earth with outstanding geomining features (mining sites) [
18] that found a way to benefit from these singular historic and touristic values and use them for local development. Among these cases are Ouro Preto and Diamantinita in Brazil, Cerro Rico de Potosí in Bolivia, Las Escombreras in Sardinia or the Kurkur-Dungul area in Egypt [
18,
19,
20].
In terms of appreciation of geology and landscape, travelling to areas of either great natural beauty or unique geographical phenomena is not something new. Nevertheless, the concept of geotourism [
21] appeared in the nineties as “geological” rather than “geographical” tourism. Geotourism, regarded as geographical tourism, was first reported by the National Geographic Society [
22]. Thus, geotourism can be seen as a branch of tourism based on geographical location and geological nature that attributes “sense of place” to the area [
14,
23]. Geotourism understands, promotes and appreciates the environment. It recognizes the importance of geological and climatic phenomena also as a determinant factor in the biotic environment [
17,
24,
25]. Nevertheless, if geotourism lacks the adequate control and prevision, it can itself pose a threat to nature [
25].
The region studied here is located in Southern Ecuador. It is a mining district where activity goes back to the Pre-Columbian era. It has a great potential as a touristic destination due to its areas of geological and mining interest, among other aspects. However, the situation of uncontrolled mining activity in the area, currently limited by legal restrictions, calls for alternatives favoring the socioeconomic development while respecting the environment and the territory. On the basis of the above, the aim of this work is to examine the potentiality of geotourism in Zaruma-Portovelo through the inventory, description and assessment of the outstanding geological and mining features in the area (sites of geological and mining interest) while exploring solutions to the environmental and socioeconomic problems related to gold mining. It is important to consider that Zaruma-Portovelo area was selected for this study due to its significance as gold deposit in Ecuador, its relevant geological-mining heritage and, principally, cultural heritage.
2. Geographic and Geological Setting
The study area lies in Southern Ecuador (
Figure 2a), in the higher part of El Oro province (municipalities of Zaruma and Portovelo), and it is known as Zaruma-Portovelo mining district. The extension of the area of interest is approximately 1000 km
2 and its average elevation is around 1200 m. The area is located in the western part of the Andean Mountains (Chilla Cordillera) and within the medium-high section of the Puyango River basin. From a geological point of view, this zone is characterized mainly by the presence of continental-volcanic, plutonic and metamorphic rocks (
Figure 2b). Furthermore, the predominant structures (faults) follow an E-W direction, and thus are discordant with the septentrional and eastern Andean system, in which the predominant direction is NNE [
26,
27,
28]. Morphologically, the most remarkable feature is the mountain relief, characterized fundamentally by noticeable fluvial incisions and by the absence of stratovolcanoes [
29], very common in the Andean Mountains.
It is an argentiferous polymetallic, epigenetic mineral deposit with an epithermal character, in which the ore occurs in seams [
28,
29,
30]. The mining activity in the Zaruma-Portovelo region traces its origins back to the Pre-Columbian era and continues nowadays. Along with the ongoing development of a planned exploitation methods (using modern equipment and machinery for the extraction, grinding, crushing, transportation and recovery processes) promoted by mining companies and associations, there still exists unofficial and uncontrolled mining activity in the area. This poses a serious threat to the natural resources and to the human activities [
31,
32]. Facing these circumstances, apart from politics limiting this kind of exploitation, it is necessary to consider alternative economic enterprises, such as geotourism, that are compatible with the planned activities under development (mining, agriculture, ranching and tourism).
5. Discussion
The described methodology [
33] enables the assignment of a semi quantitative value to the tourism resources and possibilities of the Zaruma-Portovelo mining district and its surroundings. Particularly, the process made it possible to identify and order the areas of interest from three general points of view: interest, susceptibility and protection [
12]. The same approach was used both for the geosites and the mining sites considering that the mining sites are often situated in places with special features of geology, topography, geomorphology, rivers, and a unique landscape and biodiversity [
18]. The assessment of these sites of interest pursued to facilitate the practical use of the inventory by all the potential users. The aim of the assessment was: (i) to inform non expert people about the relative value of a site compared to others in the same area, thus allowing the prioritization for use or conservation interventions and (ii) to have distinguishable groups of sites with scientific, didactic or touristic value. According to [
41], different assessment methods produce different results. This reveals the need to apply several parallel methods at a given site, since a universal application or a process that allows correlating different values have not been found yet.
The applied SWOT analysis allowed us to relate the geotourism potentiality of areas of geological and mining interest to the existing infrastructure (i.e., roads, hotels, etc.) and ongoing economic activities (mining, agriculture, livestock). Moreover, the TOWS matrix provided important information about the applicability and feasibility of geotourism development and the necessity of relating the entire potentiality of the area (i.e., biodiversity, architecture, customs, culture and history) with the geological and mining heritage [
8,
10,
12,
14,
15].
Regarding the obtained results, the assessment of the geosites and mining sites evinces: (i) the high interest of the considered areas and (ii) their proximity to each other. A viable alternative to exploit the geosites and mining sites may be the creation of a Geological-Mining Park [
17,
18,
19,
42] or, in the first instance, the creation of a Mining Route [
39,
43] connecting the different areas. The average global values of interest, DS, and Pp (
Table 8) of all the sites included in the proposed route (
Figure 7) offer a complementary criterion when evaluating different sites of interest in a specific itinerary. In general, the methodology of assessing a route on the basis of individual site values, as the proposed by [
33], has proved to be a viable and adequate approach.
The development of proposals for the use of the areas of geological-mining interest, such as the one discussed here (i.e., itinerary to visit geosites and mining sites) would [
17,
24,
25]: (i) foster the protection of the geosites and mining sites, (ii) advance the knowledge of these areas and (iii) offer new economic alternatives for the local population. This would contribute to the improvement of quality of life and to a social development in harmony with the environment [
18,
43].
In this specific case, the alternative use of geological and mining resources through geotourism would be compatible with the economic activities in the area (mining, agriculture, ranching and tourism). At the same time, if managed correctly, geotourism would benefit the protection of the geological and mining sites of interest [
25]. Furthermore, the perspective and development offered by geotourism is an innovative option against the current problems in Zaruma-Portovelo, provoked by a non-regulated and decaying mining activity.
In accordance with [
18,
19,
39], the creation of an official framework, such as a mining route, would allow visitors to learn about the diverse aspects of the geology and auriferous mining in the area in an efficient way. In general, geotourism is a key factor in the socioeconomic development of the local population, enhancing, at the same time, the preservation and protection of the geosites and mining sites [
17,
24,
44].
6. Conclusions
The research presented in this paper reveals the existence of several areas of geological and mining interest in the Zaruma-Portovelo mining district. Following the example of similar initiatives launched in some European countries, these sites could be exploited through the development of geotourism.
In detail, 16 geosites and 11 mining sites were defined in the study area. The interest of geosites reached a score of 153 (high), whereas the interest of mining sites reached an average value of 160 (high). Regarding degradation susceptibility, geosites obtained a rating of 69 (high), whereas for the mining sites this value was 131 (high). The protection priority assessed for geosites reached a score of 11 (medium), and it was 20 (high) in the case of the mining sites.
The SWOT analysis and the TOWS matrix evince that the creation of a Mining Route, a Geological-Mining Park or any other official recognition and/or protection framework for the geosites and mining sites would favor the socioeconomic development in the study area. Nevertheless, it is essential to take adequate legal and financial measures to materialize the viability of the geological and mining uses in any of the aforementioned figures of utilization.
In the Zaruma-Portovelo mining district, the progressive decrease in the gold mining and the problems derived from related activities (environmental issues and terrain destabilization) call for alternative development strategies, such as the one suggested in this paper. Geotourism, as proposed here, represents a sustainable activity, which is also compatible with the current socioeconomic activities in the area. Its implementation can be considered an adequate alternative for socioeconomic and environmental development.