1. Introduction
Studies concerning geodiversity have highlighted many different, innovative perspectives and new methods are being developed to preserve and conserve the abiotic environment. Gray stated that geodiversity comprises “the natural range (diversity) of geological (rocks, minerals, fossils), geomorphological (landforms, topography, physical processes), soil and hydrological features. It includes their assemblages, structures, systems and contributions to landscapes” [
1] (p. 12).
Several methods have been proposed to evaluate geodiversity in a qualitative and quantitative scope, either in a broad (considering scientific, economic, aesthetic, tourism, and other values) or restricted way (considering the scientific value as being central). Some works developed for the evaluation of geological and geomorphological heritage can be cited, such as those by Cendrero [
2], Panizza [
3], Brilha [
4], Pralong [
5], Reynard [
6], Pereira [
7], Reynard et al. [
8], Lima [
9], Garcia-Cortéz and Urqui [
10], Pereira [
11], Brilha [
12], and Reynard et al. [
13].
Pereira [
7] introduced the evaluation of viewpoints in the landscape as potential extrinsic character indicators. Viewpoints were identified as a specific type of geosite in the work of Fuertes-Gutiérrez and Fernández-Martínez [
14]; these authors classified geosites into five categories: points, sections, areas, complex areas, and viewpoints.
Recently, Migoń and Pijet-Migoń [
15] (p. 512) defined viewpoints as “localities which offer a wider look at the surrounding landscape and hence, better understanding of its history, spatial relationships between rock types and landform categories (i.e., geodiversity), and ongoing environmental change”. It can be seen that viewpoints are still a recent topic within the geosciences and more specific studies on the topic are lacking.
Viewpoint sites demonstrate an important relationship between geoheritage and the environment for three reasons. The first is that sites should not only focus on geology and geomorphology but also on landscape visualisation. The second reason is that environmental conditions can affect the geological parameters of the viewpoint, making the visibility of abiotic elements better or worse. The third reason is that the value of these sites is closely related to their aesthetic attributes and the very act of viewing is a basic aesthetic judgment [
16].
Among other works, it was observed in Araújo [
17] and Diniz et al. [
18] that viewpoints are underestimated when evaluating geomorphological heritage. The viewpoints evaluated in these works, although intuitively considered to be exceptional areas from an aesthetic and scientific point of view, fell into the categories of “places of geomorphological interest” or “geodiversity sites,” since the evaluation method used did not contemplate the area visualised from the viewpoints, but the sites themselves.
A problem arises because of this: which method should be employed in order to evaluate the viewpoints?
This paper aims to propose a method for evaluating viewpoint sites, considering that scientific and aesthetic values must be used as core values in quantitative evaluation.
The research is justified due to the scarcity of proper methods for quantifying viewpoint geomorphological sites in the worldwide literature. These are exceptional sites, where the heritage to be inventoried and valued is not found in the site itself (in situ) but in the landscape that can be viewed from it (ex situ).
3. Results
A quantitative evaluation was carried out for 12 viewpoints in the state of Rio Grande do Norte, Brazil. Of the sites evaluated and analysed, nine were considered to be geosites; they are: Ponta da Serra viewpoints (high scientific value), Rosado Dunes (high scientific and aesthetic value), Ponta do Mel (high scientific and aesthetic value), “Em Construção” (high scientific and aesthetic value), Sunset (high scientific value), Serra from Mossoró (high scientific and aesthetic value), Muriçoca (high scientific value), Sunset Viewpoint of Diadema (high scientific value) and Dunas de São Cristóvão (high aesthetic value). The viewpoints Tota’s, Novo Mundo, and Boa Vista were considered to be geodiversity sites, presenting medium values in the evaluation. In terms of scientific value, the highest values presented in
Table 4 were assigned to the viewpoints Ponta da Serra (16), Rosado Dunes (16), Ponta do Mel (16), Sunset (14), Serra de Mossoró (14), Muriçoca (14), Sunset Viewpoint of Diadema (14), and “Under Construction” (13). Only the viewpoints Tota’s (12), Novo Mundo (12), Boa Vista (12), and São Cristóvão Dunes (11) achieved a medium score.
Five sites had a high aesthetic value, as can be seen in
Table 5; they are the viewpoints: Serra de Mossoró (26), Ponta do Mel (24), Rosado Dunes (23), “Under Construction” (22), and São Cristóvão Dunes (22). The average scoring sites were Ponta da Serra (20), Muriçoca (20), Miradouros do Tota (18), Pôr do Sol (18), Miradouro Pôr do Sol de Diadema (18), Novo Mundo (17), and Boa Vista (16).
For the additional values, only the viewpoint Ponta do Mel (25) showed a high value; medium scores were presented at the viewpoints Boa Vista (21), Rosado Dunes (21), Tota (20), Sunset (19), Serra de Mossoró (17), and Pôr-do-Sol de Diadema (17). Five sites scored low values, namely the viewpoints São Cristóvão Dunes (16), Novo Mundo (15), Ponta da Serra (13), “Under construction” (13), and Muriçoca (13), as seen in
Table 6.
4. Discussion
The construction of this method provides a new way to evaluate the geomorphological heritage of viewpoints, in order to attribute essential characteristics to the realities of these sites without underestimating their potential for geoconservation. In this way, the observation, analysis, and evaluation are not only of the site itself but also of the viewpoint, i.e., what is visualised in the landscape.
In the works of Araújo [
17] and Diniz et al. [
18], it was observed that several geomorphological elements in the evaluation were underestimated, undervaluing the existing potential that can be representative of society, mainly due to the different dimensions and characteristics of other places.
The studies by Mikhailenko and Ruban [
16], Mikhailenko et al. [
24], and Kubalíková et al. [
25] were important steps for this type of evaluation; however, a way of linking the values of geodiversity with the central elements was barely considered for geosite definition, as portrayed by Brilha [
12], Reynard et al. [
13], and Diniz et al. [
18]. Of these, Brilha and Reynard et al. considered the scientific value to be central, while Diniz et al. considered the scientific and aesthetic values to be central.
In the proposed method, the central values are only considered to be in the visualised area, as this is the main object of interest in viewpoint studies. Additional values include both the site (in situ) and the observed area (ex situ).
In the central values, all criteria refer to the visualised area and not to the site itself. In the additional values, there are criteria that evaluate the site itself, such as accessibility, the existence of use in progress, and safety.
The Ponta da Serra, Dunas do Rosado, Ponta do Mel, Sunset Viewpoint, Serra de Mossoró, and Muriçoca Viewpoint are fundamental sites for regional palaeogeographic understanding, which contributed decisively to the high scores of these sites. The method was considered efficient in capturing the points of view with the greatest potential for exploring scientific value. The Ponta do Mel viewpoint, for example, is the only area with tectonic relief on the Brazilian coast, where there is a Quaternary uplift that is still active (
Figure 5). The base of the cliff has laterite and higher marine terrace levels from the foot of the cliff and is already inclined due to the influence of the active uplift of the area. These terraces are followed by terraced levels of lower elevation, which are less inclined as one approaches the ocean. The dynamics of the atmosphere can also be explored in the area, as the sea breezes ascend in the canyon, which allows for free flight. The image in
Figure 5 shows hang gliders flying in the area.
The Rosado Dunes, seen in
Figure 6, represent the only sample of red dunes in Brazil. The colouring is a result of the provenance of marine sediments which were added to the sediments of the Rosado cliffs. These cliffs are also inactive and formed by post-barrier unconsolidated sedimentation. Since the last marine transgression, these sediments were uplifted by the reactivation of the Afonso Bezerra fault in the area. In this 360° viewpoint, there are several records of the history of the earth over the last three thousand years.
The area of the Dunas do Rosado geosite neighbours the Rosado cliffs and also has great cultural value: some Brazilian movie scenes and Netflix series have been filmed there.
In terms of aesthetic value, the viewpoints with the highest scores were Serra de Mossoró, Ponta do Mel, and Rosado Dunes. All three sites showed important geological and geomorphological features, rarity, six-colour contrast, and a visible area of more than 500 km2 (in the case of Serra de Mossoró) and vibrant colours (in the cases of Ponta do Mel and Rosado Dunes).
The Serra de Mossoró viewpoint, for example, is a residual isolated hill, with 360° views of other high reliefs, set in a radius of at least 100 km of the flattened sandstone and limestone relief of the Potiguar Basin. The area is occupied by constructions such as communication antennas, and the construction of a 3 or 4 m high lookout on top of this peak would provide a 360° panoramic view for visitors. The cost of construction would be low, but this could boost the tourism that is already practiced in the area, with restaurants that explore the lookout at a slightly lower level than the top of this relief.
Figure 7 shows hundreds of km
2 of relief that was flattened during the Quaternary, around the Serra de Mossoró. The landscape is extremely complex with natural vegetation and fruit plantations (melons are grown for export). This image shows the Atlantic Ocean (more than 35 km away from the lookout) and even the port-island of Areia Branca, an artificial island that functions as a port for the export of the area’s salt production; the port is about 55 km away from the lookout. As the viewpoint is 360° and the hill is in extremely isolated relief, it is possible to see the dome of the Serra do Mel, the Mossoró River valley, the crystalline plateaus of the interior of the state, and the salt production in the nearby estuaries. It is certainly one of the most privileged points to observe geomorphological forms and processes at great distances; the method was effective in capturing the high aesthetic value of the main areas where the method was tested.
The aesthetic values varied much more between sites, mainly due to the difference in the proportion of viewable area; higher sites with more isolated reliefs allow wider views and are likely to score higher on this value. However, this criterion can be offset by the rarity criteria, since sites with restricted vision can provide the visualisation of extremely rare forms in the context studied, as in the case of Ponta do Mel.
Figure 8 shows a representation of two types of geosites, Serra de Mossoró and Ponta do Mel, with different dimensions: the first has a 360° view, while the second represents a more restricted observation. The Serra de Mossoró geosite, with a large observable area, obtained the highest score in terms of aesthetic value, while the Ponta do Mel geosite, with a more restricted view, scored low in criterion B6 but maintained its high score in aesthetic value, due to rarity (B7) of the observable area from the viewpoint.
The Dunas de São Cristóvão viewpoint did not have a high scientific value, but it can be considered a geosite for its high aesthetic value, which is due to the vibrant colours of the extremely heterogeneous landscape that can be seen in the area. The viewpoint has a 360° view, excellent visibility, and provides a view of the Atlantic Ocean. The dunes follow a flow of bypass parallel to the coastline; this current flow is due to the predominant E-W wind direction, which is the same as the predominant direction of the coastline, as seen in
Figure 9.
For the additional values, only one site had a high rating, due to the fact that some viewpoints still do not have tourist infrastructure that can draw the attention of visitors. The geosites that have been noted have a lot of geological/geomorphological potential that needs to be publicised to favour not only tourists, but the local community, helping to increase income in this sustainable tourism segment.
5. Conclusions
The theme of viewpoints is relatively recent in geodiversity studies. In most of the evaluation methods used to date, for both geological and geomorphological heritage, these sites were underestimated. Thus, a specific quantification is needed to address their particularities and highlight their value to society, attracting visitors in general, so that the sites can be used in a sustainable and profitable way for the local community.
From the proposed method, it was possible to consider eight geosites in terms of scientific value. Four of these also obtained a high aesthetic value: Serra de Mossoró, Ponta do Mel, Dunas do Rosado, and a Viewpoint “under construction”. Dunas de São Cristóvão was considered a geosite only for its aesthetic value, which shows the importance of considering aesthetics in the evaluation, as it exposes the degree of visibility of the geomorphological elements, as well as the rarity of the observable environment (in a regional or local configuration). The aesthetic value of a site has a high power to attract visitors to the area to be conserved.
The method developed in this paper has shown a positive result for viewpoint evaluation, highlighting its main elements, besides what is seen in the landscape, and exposing a specific focus, which has not been seen in other proposals. It is applicable to any area with a natural viewpoint.