Geoheritage of the Príncipe UNESCO World Biosphere Reserve (West Africa): Selected Geosites

Considered by many to be one of the last hidden treasures, the Príncipe Island, off the coast of west-central Africa, is part of the twin-island state of São Tomé and Príncipe—the second smallest country in Africa. The islands are known as the “Galápagos of Africa” due to the high number of endemic plant and animal species, especially vascular plants, mollusks, insects, birds, reptiles, and bats. They are a melting pot of influences from different cultures and have a unique and authentic character in terms of language, culture, gastronomy, traditions, and geology. The Príncipe Island is 30.4 My old, being the oldest volcanic island of the Cameroon Volcanic Line located at the Gulf of Guinea (West Africa). It has an area of 142 km2 and a population of only about 8420 people. Rainforest covers the island’s basaltic peaks and slopes, cascading down to spectacular deserted beaches. In 2012, the Príncipe Island was declared UNESCO World Biosphere Reserve. However, there is a great lack of knowledge about its geodiversity and geological heritage. The aim of this work is to describe the geoheritage of the Príncipe Island based on seven selected geosites that represent the major geological characteristics of the island by interconnecting each episode of its formation with the observable products in outcropping. The resulting narrative makes it possible to support educational activities and geotourism initiatives that are fundamental to the promotion of sustainable development in this tiny African country. By integrating the geodiversity dimension to the biodiversity dimension, this research intends to display a holistic vision of the natural heritage of the Príncipe Island and to contribute to assist United Nation’s goals regarding Small Island Developing States.


Introduction
Natural heritage refers to natural features, geological and physiographic formations, and defined areas that constitute the habitat of threatened animal and plant species and natural sites of value from the point of view of science, conservation, or natural beauty (UNESCO 2023).It includes both biodiversity and geodiversity components and it can represent the major stages of Earth's history, including the record of life, and significant geological processes that have shaped the planet.Geodiversity is the abiotic equivalent of biodiversity, i.e., it describes the variety of physical processes operating on planet Earth and the resulting rocks, minerals, fossils, sediments, soils, landforms, landscapes, and habitats found on the planet today (Gray 2016).
Geological heritage comprises concrete examples of geodiversity which may be specifically identified as having exceptional scientific, educational, touristic, or cultural significance (Brilha 2005;Henriques et al. 2011).Its social use can contribute to the promotion of sustainable development, geoeducation, and geotourism, which would represent an added value for any territory.This is particularly important for African countries where geoheritage is under-represented at global scale and remains to be analyzed and uncovered (Neto & Henriques 2022).The objective of this paper is therefore to present the geoheritage of Príncipe Island, based on seven selected geosites 118 Page 2 of 13 representing the main geological features of the island, complementing similar works previously developed in São Tomé Island (Henriques & Neto 2014, 2019).The results can contribute to support geoeducation activities and geotourism initiatives and to promote sustainable development among African Small Island Developing States managed by the United Nations (UN 2023).

Geological and Geographical Setting
The Príncipe Island is located in the Gulf of Guinea, on the Cameroon Volcanic Line (CVL), with coordinates 1° 36′ N-7° 23′ E and an area of 136 km 2 (Fig. 1).The CVL is an extensional zone that formed in the continental lithosphere at 65 My due to changes in the stress field in the nearby high lithosphere (Burke 2001;Brownfield & Charpentier 2006).
It is divided into two parts: the offshore part lies at the apex of an asymmetric arc 200 km long and 3 km high, with large volcanic center containing igneous material consisting mainly of plutonic alkaline basaltic and alkaline basalt rings (Heldberg 1969;Déruelle et al. 1991Déruelle et al. , 2007)), represented by the islands of Annobón (Pagalú), São Tomé, Príncipe, and Bioko (Meyers et al. 1998;Meyers & Rosendahl 1991).
Volcanic activity associated with the CVL ranges from the Paleocene, about 66 My, to the present (Déruelle et al. 1991(Déruelle et al. , 2007)).Volcanism in the continental part of the CVL started about 42 My ago, while offshore volcanism started about 30.4My ago (Grunau et al. 1975).Volcanism continues to the present in both the oceanic and continental parts (Adams 2022).
The Príncipe Island was formed 30.4My ago and it is the oldest island among the three oceanic volcanic islands of the CVL at the Gulf of Guinea (Fig. 1).The island is characterized by its gentle topography in its northern half, mainly composed of basaltic rocks, frequently covered by laterite crusts easily observable at the airport, and by its mountain range in the southern part, which is composed of several phonolitic peaks and tephrites with altitudes between 500 and 948 m, on which the primary rainforest is found (Cotelo Neiva & Correia Neves 1957;Schlüter & Trauth 2006;AfriMab et al. 2013).
Petrology and the K-Ar geochronology of the island were described by Fitton and Hughes (1977) and Dunlop and Fitter 1979).The earliest rocks (30.4 My) are the basal hyaloclastite breccia, containing fragments of fresh tholeiite and representing a submarine phase in the evolution of the island (Schlüter & Trauth 2006).
At the upper part of this basal unit, sub-horizontal basaltic flows occur, intruded by plugs of tristanite and trachyphonolite.The basaltic flows may be divided into a bottom series of alkaline basalt and hawaiite, overlain by a cluster of nephelinite and basanite flows, which Fitton and Hughes (1977) have considered the oldest and the youngest lava series, respectively.The lavas of both series have been overlain by tristanites, phonolites, and trachyphonolitic lavas in the center and in the south of the island (Schlüter & Trauth 2006).
The younger lava series (trachyphonolitic suite) range in age from 5.6 (nephelinite) to 3.5 My (basanite).The plugs ages range from 6.9 to 3.9 My.Dunlop and Fitter (1979) reported an Rb-Sr isochron of ca.5.9 My, set by the younger lava series and all the intrusive rocks, which suggests a cogenetic link between intrusive rocks and the youngest lava series.The Sr, Nd, and Pb isotopic compositions for Príncipe are mainly drawn from Halliday et al. (1990) and Halliday et al. (1988).The groundmass of the younger lava series contains alkali feldspar, nepheline, and apatite; the phonolitic lavas are porphyritic with a microlitic groundmass, dominated by phenocrysts of nepheline, Fig. 2 Geologic map of Príncipe Island (adapted from Teixeira 1949, Neiva et al. 1956, Schlüter and Trauth 2006) 118 Page 4 of 13 sanidine, aegirine-augite and barkevicite, titanite, and magnetite with possible sodalite and plagioclase (Schlüter & Trauth 2006) (Fig. 2).
The sedimentary, stratigraphic, and paleontological record includes Miocene fossiliferous limestones referred by Henriques da Silva (1956) to a small outcrop located at 1300 m southeast of the capital (Santo António), between Ubá and Forca Stream (Ribeira da Forca), displaying an assemblage of fish teeth, coralline algae, echinoderms, bivalves, and gastropods.Quaternary benthic and planktonic foraminifera were described by Reis Moura (1970) from sand samples collected in several beaches located around the island.
Despite their different ages, the geological constitution of the Príncipe Island is like the São Tomé Island.From the geomorphological point of view, the Príncipe Island also shares the characteristics of the São Tomé Island, displaying strong orographic relief; its highest point is located at Pico do Príncipe, which is 948 m high above sea level.
Príncipe is the first UNESCO World Biosphere Reserve for the archipelago of São Tomé and Príncipe and became the first African reserve to join the World Network of Island and Coastal Biosphere Reserves, launched in 2009 by UNE-SCO MAB Programme to foster sustainable development in islands and coastal areas and to promote adaptation and mitigation strategies on climate change (NICBR 2023).The Biosphere Reserve includes the whole surface of the Príncipe Island and its islets Bom Bom, Boné do Jóquei ("Jockey's Cap"), Mosteiros, Santana, and Pedra da Galé, as well as Tinhosas islets, situated about 20 km southwest of the island.It also includes an extensive marine area up to 50 m deep around Príncipe and Tinhosas.As of 2016, it has also been integrated as a RAMSAR Territory (Tinhosas islets) for its relevance for the migratory seabirds (UNESCO 2023) (Fig. 3).

The Geoheritage of the Príncipe Island
The geoheritage of São Tomé Island has been previously described (Henriques & Neto 2014, 2019), based on a qualitative approach developed by Pena dos Reis and Henriques (2009).The same method was applied to the geoheritage of the Príncipe Island, therefore complementing the knowledge about the geoheritage of the whole country.Regarding geoheritage types (Habibi et al. 2018), the Príncipe Island essentially displays geosites of igneous type, related to its volcanic origin, but stratigraphical, paleontological, sedimentary, geomorphological, pedological (laterite crusts), and economic types (laterites as raw material and oil seeps reflecting hydrocarbon migration) are also present (Figs. 4  and 5).

Inventorying and Evaluation Procedures
This works refers to a small area with few geosites, where quantitative assessment does not make much sense (Brilha 2016).Furthermore, the country does not have any geoconservation legislation and the public awareness about local geoheritage is incipient.Such scenario suits best a qualitative approach regarding geoconservation inventorying and assessment, like the one developed by Pena dos Reis and Henriques (2009), which is particularly helpful to complement the current conservation status of areas already legally protected for non-geological reasons, as is the case of this African island (Henriques et al. 2013a, b).Moreover, this qualitative assessment method enables the integration of geoheritage contents that are meaningful to non-specialists (Pena dos Reis & Henriques 2009), therefore fostering the link between people, landscapes, and their culture, as well as the geoheritage's conservation and valuation (Henriques et al. 2013a, b;Pena dos Reis and Henriques 2018).Also, Toteu et al. ( 2010) consider the importance of integrating science and local indigenous knowledge and beliefs when aiming at encouraging the holistic co-curatorship of Africa natural heritage.As so, the local community must be involved in all geoconservation activities, such as inventory, evaluation, conservation, valuation, and monitoring, in order to effectively safeguard geological objects displaying geoheritage contents (Tavares et al. 2015;Henriques et al. 2020).
According to Pena dos Reis and Henriques (2009), the geoheritage assessment can be based on the geoheritage content displayed by geological objects.Such assessment, qualitative in nature, depends on both the relevance of the meanings attributed to the objects by the scientific communities (defined as relevance grade) and the public understanding of such meanings in relation to the social use of the objects (defined as abstract perceptiveness).Geoheritage content is scored into three categories of increasing importance.These are rank I, indicial content; rank II, documental, iconographic, and symbolic contents; and rank III, conceptual and scenic contents.Being an open classification system, new geosites can be integrated, if they present heritage content.

Geosites Inventorying
This inventory was carried out from a regional perspective, with the aim of developing a geoconservation strategy and a geotourism and education program involving the two islands (São Tomé and Príncipe) in the future.The map in Fig. 3 shows the location of the seven inventoried geosites, including three viewpoint geosites sensu (Migon & Pijet-Migon 2017), which were selected taken several reasons into account: representativeness of the geological history of the island, accessibility (by walking, by car, or by boat), and attractiveness (sites generally suggested by the tour operators who provide local guides to assist the visitors).The following is a description of each of the selected geosites, as well as the geoheritage contents they display.The information is organized with a view to its use in the form of a geo-itinerary that allows the effective interpretation of geoheritage issues targeting a non-specialized public (Henriques & Pena dos Reis 2021).
The Bom Bom Islet (coordinates: 1° 42′ 3″ N, 7° 24′ 13″ E) forms the northern end of the island.This 59-m high islet is connected to the main island by a sandy spit, on the west side of which there are two small rocky islets.The Bom Bom Islet is densely forested and has a sheer cliff on its seaward side, against which the sea frequently breaks.There are basalt outcrops on the isthmus of Bom Bom, crossed by strong parallel trachyte dykes, with a thickness of about 5 m in the N 18° E direction (Fig. 6A and B).These lavas correspond to the oldest series of lavas of subaerial eruptions occurred in the island (24 My) (Fitton & Hughes 1977), therefore displaying documental content; moreover, the trachyte dykes suggest their origin in an obvious way, and such feature corresponds to the concept of indicial content (Pena dos Reis & Henriques 2009).The hotel located on the adjacent beach and the restaurant on the islet, with a walkway connecting the beach to the islet, provide accessibility and attractiveness to this geosite, which is widely known on the world tourist circuits due to its scenic content.
The Papagaio Peak (coordinates: 1° 36′ 43″ N, 7° 23′ 31″; 680 m altitude) is a volcanic peak, of phonolitic origin, located in the Natural Park of Príncipe, created by Law 7/2006.It is an emblematic peak of the island, visible from the capital, and surrounded by secondary and primary forests.It has the same name of the largest river of the island.This place represents the intermediate series (6.9 My), and overlaps the oldest series (Fitton & Hughes 1977), corresponding to a geological episode of the island's geohistory, therefore displaying documental content; as this structure is easily understood due to then clear physical relation between the event and its effects, this geosite also displays indicial content (Pena dos Reis & Henriques 2009).Along the route to the summit, there are several trails where one can observe endemic species of flora and fauna, namely giant trees ("Ocás"), butterflies, and amazing orchids.From the top, it is possible to enjoy different views of the whole island, which provides high scenic content to this geosite (Fig. 7A and B).
The Agulhas Bay (coordinates: 1° 33′ 20″ N, 7°20′ 32″ E-1°36′ 19″ N, 7°20′ 05″ E) is surrounded by a set of phonolitic peaks that look like needles ("agulhas" in Portuguese) pointed to the sky.From the Agulhas Bay or from the São Joaquim viewpoint, it is possible to see the various phonolitic towers that characterize the landscape of the south of the Príncipe Island (Fig. 8).These rocks also belong to the intermediate phase of volcanic activity, represented by rocks of the protolithic types, trachyte and trachyte phonolitic (Fitton & Hughes 1977).Besides the documental content, the clear relationship between volcanic and erosional activity also provides indicial content to the geosite.From the Agulhas Bay by boat or from the viewpoint of São Joaquim, it is possible to enjoy the surrounding landscape which displays high scenic content (Pena dos Reis & Henriques 2009).
The Banana Beach (coordinates: 1° 41′ 24″ N, 7° 26′ 30″ E) is a typical tropical beach located at Roça Belo Monte (2023), which golden sands in the shape of a banana can be first seen from the cliff top before descending to sea level.It is considered by many to be one of the last hidden gems and one of the most beautiful beaches of the country.Large basaltic rocks with striated structure, probably caused by marine erosion, outcrop along the seashore (Fig. 9).They represent the most recent series of volcanism on the island (6 My) and are characterized by basanite lava flows, which form a prominent cliff along the west coast and extend over most of the northern part of the island (Fitton & Hughes 1977).Besides the documental contents, this geosite, which The Roça Terreiro Velho (coordinates: 1° 36′ 37″ N, 7° 25′ 13″ E) is famous for being the place of the African continent where the first cocoa plant was introduced (1819).At Terreiro Velho, the cocoa production has continued since then, and it currently produces the famous Claudio Corallo's cocoa, considered one of the best chocolates in the world (Corallo 2023).The outcropping rocks represent the modern series, mostly basaltic in nature (6 My) (Fitton & Hughes 1977), therefore corresponding to documental content; as this geosite provides an almost 360° view of the Príncipe Island, it also displays scenic content, and this includes the famous rock shaped like a cap, the Boné do Jóquei ("Jockey's Cap"), that meets the concept of symbolic content (Pena dos Reis & Henriques 2009; Fig. 10A and B).Those three geosites are in fact viewpoint geosites, i.e., places that offer a view of features and areas which do have geoheritage contents (Migon and Pijet-Migon 2017. The Oquê Pipi Waterfall (coordinates: 1° 35′ 52″ N, 7° 24′ 50″ E) structurally corresponds to an escarpment of about 30 m where water gushes out and forms a natural pool providing great scenic content (Pena dos Reis & Henriques 2009).The fall enables a broad view of the most recent series of volcanism, therefore displaying documental content.A small trail takes visitors through the rainforest to the Claudio Corallo's cocoa plantation (Fig. 11).Royal Astronomical Society 2022) (Fig. 12).In this sense, it corresponds to the concept of symbolic content (Pena dos Reis & Henriques 2009), and it was included in the country's indicative list of World Heritage candidate sites in 2023.The outcrops show rocks of the older series that are mixed with phonolitic rocks forming a lava tongue that extends northwards to the basaltic plateau composed of lavas of the younger series (Fitton & Hughes 1977), therefore displaying documental content (Pena dos Reis & Henriques 2009).At the confluence of Izé creek (Roça Sundy) and Duas Águas creek, there are oil seeps flowing through fractures of highly altered phonolitic rocks, accompanied by gas emissions (Teixeira 1949).These oil seeps meet the concept of indicial content, a local-scale content which exhibits clear relation between elementary geological processes (the hydrocarbon migration within a petroleum system) and their resulting products (Pena dos Reis and Henriques 2018).

Geosite Assessment
The qualitative assessment of the seven geosites described in this work displays value-added heritage contents that can be used to ground geoeducation activities and geotourism initiatives, key strategies for promoting sustainable development at Príncipe Island (Table 1).Most of the selected geosites display more than one type of value, which significantly increases their heritage value (Pena dos Reis & Henriques 2009).Banana Beach, Roça Terreiro Velho, and Roça Sundy are the most relevant geosites in terms of geoheritage value, requiring geoconservation measures, not so much of conservation of the geological heritage, but more of valuation and monitoring.The other four geosites also require the implementation of actions aimed at its valuation and monitoring.Local tour operators and public agents, in articulation with geoconservation experts, hold responsibility of designing and implementing relevant geotourism resources (e.g., field guidebooks, websites, trails, leaflets, mobile applications, and interpretative panels) targeting a non-specialized public and appealing educational resources to enable effective interpretation of Príncipe geoheritage, both for visitors and for local people who can assist them during their stay on the island.
In order to enable the public understanding of geological processes that formed the island, the meanings displayed by the seven geosites referred to above can ground the design of a geo-itinerary which aim at telling the geological history of the island, supported by appropriate interpretative digital tools, since internet coverage in the country is quite good.Geosites must be organized and described using meaningful messages, i.e., in a context of simplification of the geoscientific discourse to help develop the understanding of a more general public ("storytelling"), rather than geosciences experts (Henriques & Pena dos Reis 2021).

Discussion
Geodiversity is an important resource for human development, influencing the distribution of flora and fauna and the functioning of ecosystems (Kubalíková 2013;Schrodt et al. 2019).In addition to its scientific value, geodiversity is also an important resource for education, tourism, and the cultural identity of local communities (Brilha 2016).
The African continent, especially sub-Saharan Africa, still lags behind other continents in terms of geoconservation research, therefore is wasting the use of its geological heritage as a tool fostering sustainable development of local communities (Henriques et al. 2013a, b;Neto & Henriques 2022).The African reality in general, with some exceptions, is dominated by low levels of education, reduced or non-existent accessibility, absence of adequate legal instruments, and lack of critical mass, among other constraints, as African countries and their governments are mainly focused on solving the basic problems of their populations.Limited resources and remoteness are the current reality of São Tomé and Príncipe as a Small Island Developing State, where references to geosites' inventory were null until recently, despite the scenic beauty of the volcanoes recognized by different authors (Schlüter & Trauth 2006) and the uniqueness Many of the instruments currently used to assess the heritage value of geosites have been designed and tested in completely different socio-geographic contexts from the one that characterizes São Tomé and Príncipe.Western approaches to geoconservation based only on the scientific perspective, despite its social dimension, cannot be successfully applied in Africa (Matshusa et al. 2021).Also, Western geotourism theories cannot fully explain the dynamics of geotourism in African countries, mainly due to the deep cultural, political, and historical differences between Africa and Europe (Stone and Nyaupane 2016).
First approaches to the country geoheritage were developed in São Tomé Island (Henriques & Neto 2014, 2019), using an integrated evaluation system, qualitative in nature, and based on geoheritage contents that geosites may display (Pena dos Reis & Henriques 2009).The same method was applied to the Príncipe Island, therefore enabling comparative analysis between the two islands and contributing to the compilation of a future inventory of the national geological heritage.
The social and human dimension, combined with the economic aspects, is a precondition for the dissemination of any science in developing countries, including geoconservation as an emergent geoscience (Henriques et al. 2011).Most of the selected geosites described for the Príncipe Island display more than one type of content, which significantly increases their heritage value and their geoconservation priority (Pena dos Reis & Henriques 2009).Such condition usually requires the implementation of protection measures against natural and man-made threats, which makes little sense in a territory with an area of 142 km 2 and a population of only about 8420 people, whose economic activities are essentially fishing and agriculture (especially cocoa, coffee, and copra) (UNESCO 2023), in addition to the development of the tourism sector in recent years.
But geoconservation concerns not only to inventory, evaluation, and conservation of the geological heritage; it also refers to the implementation of specific procedures that aim at its valuation and monitoring.Progress has been made on the Príncipe Island, both in terms of sustainability and the conservation of flora and fauna and the development of ecotourism.But it remains the need of creating a critical mass of communities and groups interested in geoconservation and geotourism and raising their awareness of the importance of the geological heritage that is the habitat of the island's already protected fauna and flora.As a node (18: Príncipe "Einstein's Theory of Relativity") of the "African Pole of Rotation" Corridor, the disclosure of this island's geoheritage can reinforce the potential of this Corridor to develop a sustainable tourism path, therefore contributing to stimulate the growth of all sectors in the tourist, education and entrepreneurship industries, and the community at large (Toteu et al. 2010).People's jobs, properties, or businesses, as well as local groups reviving traditional cultural demonstrations, can benefit from this challenge, which leads to changes to sustainable livelihoods.They include the consumption of local products and services, like the restoration of houses using local raw materials instead of exogenous coating products (Henriques et al. 2020;Fig. 4).
Based on literature review and recent fieldwork, this research also highlights the need to update the incipient and old geological cartography of the two islands, being a paradigmatic example of close connections between scientific research and Technical Applications of Geoconservation, the last ones concerning the conservation, valuation, and monitoring of the selected geosites to guarantee future research (Henriques et al. 2011).

Conclusion
The Príncipe Island is one of three existing oceanic volcanic islands of the Gulf of Guinea (West Africa).It is geologically the oldest island of the Cameroon Volcanic Line (CVL), formed 30.4My ago, but it is worldwide known by its singular biodiversity which led to its nomination by UNESCO as a Biosphere Reserve in 2012.The present work inventories, characterizes, and evaluates By representing different phases of the volcanic activity that formed the island locally overlapped by Cenozoic deposits, each of the selected geosites displays documental content.Outcrops are covered or surrounded by deep green and very dense secondary and primary forests, which contrast with turquoise sea waters, and make up sceneries of great aesthetic beauty, i.e., with scenic content.In some of them, it is possible to perceive clear physical relation between volcanic events and its effects, and therefore assign them indicial content.This is the case of the phonolitic structure of Papagaio Peak, the eroded phonolitic peaks of Agulhas Bay, and the strong parallel trachyte dykes that cross basalt outcrops on the isthmus of Bom Bom Islet.By showing clear physical relation between an event and its effects, the oil seeps at the confluence of Izé creek (Roça Sundy) and Duas Águas creek can be also assigned to the indicial content concept and are of interest to the petroleum industry.Some of the geosites correspond to viewpoints geosites, i.e., places whose geomorphology stimulated the visual perception of the first settlers, who gave them names of objects to which they resemble, thus endowing them with a symbolic content.The phonolitic peaks that look like needles of the Agulhas Bay, the bizarre shape of the Banana Beach, and the Jockey's Cap of the Roça Terreiro Velho are examples of collectively accepted designations related to geological objects largely enjoyed due to reasons other than geological ones.
Through the interpretation of the recognizable geoheritage contents displayed by the selected geosites, it is possible to design a geo-itinerary that narrates the geological history of the island, as well as that of the CVL, where the island is located.This will enrich the already consolidated narrative on the island's biodiversity, complementing it with its geodiversity.Fostering a holistic perspective of nature is a better way to address the challenges inherent in São Tomé and Príncipe as a Small Island Developing State, namely limited resources, remoteness, and excessive dependence on international trade.However, the weaknesses usually associated with this type of territories can be seen as opportunities to implement sustainable development strategies if the natural values that remain almost untouched there are enhanced, namely through geotourism, by training local guides and producing appropriate information about the island's geoheritage.

Fig. 1
Fig. 1 Location of the Príncipe Island within the Cameroon Volcanic Line

Fig. 3
Fig. 3 Location of selected geosites of the Príncipe Island and area of the UNESCO World Biosphere Reserve of Príncipe Island, including the Tinhosas islets

Fig. 4 Fig. 5
Fig. 4 Laterites as raw material used at a local bar (Photo by Ruldmisa Borges)

Fig. 6 Fig. 7 Fig. 8
Fig. 6 Bom Bom Islet as seen from the beach (A) and from the airplane (B) showing the oldest series of lavas of subaerial eruptions occurred in the island (courtesy of Diana Relego, HBD STP 2023)

Fig. 9
Fig. 9 Banana Beach as seen from the cliff top before descending to sea level showing the most recent series of volcanism on the island

Fig. 11
Fig. 11 Oquê Pipi Waterfall showing the most recent series of volcanism occurred in the island (in Saoferias 2023)