On the fringes of Atlantic Rock Art: A multidisciplinary approach to El Riscal (Seville, Spain)

En los márgenes del Arte Rupestre Atlántico: una aproximación multidisciplinar a El Riscal (Sevilla, España)

Miguel Ángel Rogerio Candelera Instituto de Recursos Naturales y Agrobiología de Sevilla, Consejo Superior de Investigaciones Científicas, m.rogerio@csic.es (corresponding author)

Alba Fuentes Porto Departamento de Bellas Artes, Universidad de La Laguna, afuentep@ull.edu.es

Timoteo Rivera Jiménez Departamento de Prehistoria y Arqueología, Universidad de Sevilla, tinorivera17@gmail.com

Jordi Ibáñez Insa Geosciences Barcelona, Consejo Superior de Investigaciones Científicas (GEO3BCN-CSIC), jibanez@geo3bcn.csic.es

José Antonio Lozano Rodríguez Instituto Español de Oceanografía, Islas Canarias, IEO-COC, Consejo Superior de Investigaciones Científicas, ja.lozano@ieo.csic.es

A. César González García Instituto de Ciencias del Patrimonio (Incipit), Consejo Superior de Investigaciones Científicas, a.cesar.gonzalez-garcia@incipit.csic.es

Raquel Montero Artús Departamento de Prehistoria y Arqueología, Universidad de Sevilla, raquelmontero@us.es

Leonardo García Sanjuán Departamento de Prehistoria y Arqueología, Universidad de Sevilla, lgarcia@us.es

ABSTRACT

RESUMEN

CONTENT

1. INTRODUCTION  ⌅

One of the most outstanding elements of world cultural heritage is rock art. Whether of additive (painting) or subtractive (engraving) nature, rock art often provides the only remaining graphic traces of prehistoric world views. Iberia is rich in rock art, with an extensive record of sites and a remarkable diversity of styles. This includes both Palaeolithic art (with two UNESCO World Heritage sites in Altamira and Foz Côa) as well as late prehistoric art (Neolithic, Copper Age, Bronze Age and Iron Age) with a host of styles and media (Levantine, Schematic, Macro-Schematic, petroglyphs, ‘megalithic’ art, engraved stelae, etc.) and hundreds of recorded sites. Going all the way back to the beginning of the 20th century (Breuil and Burkitt, 1929Breuil, H. and Burkitt, M. (1929). Rock Painting of Southern Andalusia. A Description of a Neolithic and Copper Age Art Group. Oxford: Clarendon Press.Breuil, H. and Burkitt, M. (1929). Rock Painting of Southern Andalusia. A Description of a Neolithic and Copper Age Art Group. Oxford: Clarendon Press.), the literature on Iberian late prehistoric rock art is quite extensive, including several hundred papers and dozens of monographs (syntheses in Beltrán Martínez, 1982Beltrán Martínez, A. (1982). Rock Art of the Spanish Levant. Cambridge: Cambridge University Press.Beltrán Martínez, A. (1982). Rock Art of the Spanish Levant. Cambridge: Cambridge University Press.; Peña Santos, 2001Peña Santos, A. (2001). Petroglifos de Galicia. La Coruña: Vía Láctea.Peña Santos, A. (2001). Petroglifos de Galicia. La Coruña: Vía Láctea.; Escoriza Mateu, 2002Escoriza Mateu, T. (2002). El Arte Rupestre Levantino del Arco Mediterráneo de la Península Ibérica. Mujeres, Representaciones y Actividades. British Archaeological Reports. International Series 1082. Oxford: Archaeopress.Escoriza Mateu, T. (2002). El Arte Rupestre Levantino del Arco Mediterráneo de la Península Ibérica. Mujeres, Representaciones y Actividades. British Archaeological Reports. International Series 1082. Oxford: Archaeopress.; Cruz Berrocal, 2005Cruz Berrocal, M. (2005). Paisaje y Arte Rupestre. Patrones de Localización de la Pintura Levantina. British Archaeological Reports International Series 1409. Oxford: Archaeopress.Cruz Berrocal, M. (2005). Paisaje y Arte Rupestre. Patrones de Localización de la Pintura Levantina. British Archaeological Reports International Series 1409. Oxford: Archaeopress.; Díaz-Guardamino, 2010Díaz-Guardamino, M. (2010). Las Estelas Decoradas de la Prehistoria de la Península Ibérica. PhD Thesis dissertation. Madrid: Universidad Complutense de Madrid. Available at: https://hdl.handle.net/20.500.14352/47389.Díaz-Guardamino, M. (2010). Las Estelas Decoradas de la Prehistoria de la Península Ibérica. PhD Thesis dissertation. Madrid: Universidad Complutense de Madrid. Available at: https://hdl.handle.net/20.500.14352/47389.; García Arranz et al., 2012García Arranz, J. J., Collado Giraldo, H. and Nash, G. (Eds.) (2012). The Levantine Question. Budapest: Archaeolingua.García Arranz, J. J., Collado Giraldo, H. and Nash, G. (Eds.) (2012). The Levantine Question. Budapest: Archaeolingua.; Bettencourt et al., 2017Bettencourt, A. M. S., Santos Estevez, M., Sampaio, H. and Cardoso, D. (Eds.) (2017). Recorded Places, Experienced Places. The Holocene Rock Art of the Iberian Atlantic North-West. British Archaeological Reports International Series 2878. Oxford: Archaeopress.Bettencourt, A. M. S., Santos Estevez, M., Sampaio, H. and Cardoso, D. (Eds.) (2017). Recorded Places, Experienced Places. The Holocene Rock Art of the Iberian Atlantic North-West. British Archaeological Reports International Series 2878. Oxford: Archaeopress.). Regarding archaeoastronomical studies, the very development of this approach is linked to the Iberian archaeological record (e. g., Belmonte, 1999Belmonte, J. A. (1999). Las Leyes del cielo. Astronomía y civilizaciones antiguas. Madrid: Temas de Hoy.Belmonte, J. A. (1999). Las Leyes del cielo. Astronomía y civilizaciones antiguas. Madrid: Temas de Hoy.; Belmonte and Hoskin, 2002Belmonte, J. A. and Hoskin, M. (2002). Reflejo del Cosmos: Atlas de Arqueoastronomía del Mediterráneo antiguo. Madrid: Equipo Sirius.Belmonte, J. A. and Hoskin, M. (2002). Reflejo del Cosmos: Atlas de Arqueoastronomía del Mediterráneo antiguo. Madrid: Equipo Sirius.).

Despite this long history of research, recent methods have provided fresh key evidence to understand Iberian late prehistoric rock art under a new light. Examples of this abound, including the use of digital technologies (Díaz-Guardamino et al., 2015Díaz-Guardamino Uribe, M., García Sanjuán, L., Wheatley, D. and Rodríguez Zamora, V. (2015). “RTI and the study of engraved rock art: a re-examination of the Iberian Late Bronze Age stelae of Setefilla and Almadén de la Plata 2”. Digital Applications in Archaeology and Cultural Heritage, 2, pp. 41-54. DOI: https://doi.org/10.1016/j.daach.2015.07.002.Díaz-Guardamino Uribe, M., García Sanjuán, L., Wheatley, D. and Rodríguez Zamora, V. (2015). “RTI and the study of engraved rock art: a re-examination of the Iberian Late Bronze Age stelae of Setefilla and Almadén de la Plata 2”. Digital Applications in Archaeology and Cultural Heritage, 2, pp. 41-54. DOI: https://doi.org/10.1016/j.daach.2015.07.002.; Cerrillo Cuenca et al., 2019Cerrillo Cuenca, E., Bueno Ramírez, P. and De Balbín Behrmann, R. (2019). “3DMeshTracings: A protocol for the digital recording of prehistoric art. Its application at Almendres cromlech (Évora, Portugal)”. Journal of Archaeological Science: Reports, 25, pp. 171-183. DOI: https://doi.org/10.1016/j.jasrep.2019.03.010.Cerrillo Cuenca, E., Bueno Ramírez, P. and De Balbín Behrmann, R. (2019). “3DMeshTracings: A protocol for the digital recording of prehistoric art. Its application at Almendres cromlech (Évora, Portugal)”. Journal of Archaeological Science: Reports, 25, pp. 171-183. DOI: https://doi.org/10.1016/j.jasrep.2019.03.010.), the application of analytical methods to date and characterise pigments (Carrera Ramírez and Fábregas Valcarce, 2002Carrera Ramírez, F. and Fábregas Valcarce, R. (2002). “Datación radiocarbónica de pinturas megalíticas del Noroeste peninsular”. Trabajos de Prehistoria, 59 (1), pp. 157-166. DOI: https://doi.org/10.3989/tp.2002.v59.i1.216.Carrera Ramírez, F. and Fábregas Valcarce, R. (2002). “Datación radiocarbónica de pinturas megalíticas del Noroeste peninsular”. Trabajos de Prehistoria, 59 (1), pp. 157-166. DOI: https://doi.org/10.3989/tp.2002.v59.i1.216.; Rogerio-Candelera et al., 2018Rogerio-Candelera, M. A., Bueno Ramírez, P., De Balbín Behrmann, R., Dias, M. I., García Sanjuán, L., Coutinho, M. L.,… and Gaspar, D. (2018). “Landmark of the past in the Antequera megalithic landscape: a multi-disciplinary approach to the Matacabras rock art shelter”. Journal of Archaeological Science, 95, pp. 76-93. DOI: https://doi.org/10.1016/j.jas.2018.05.005.Rogerio-Candelera, M. A., Bueno Ramírez, P., De Balbín Behrmann, R., Dias, M. I., García Sanjuán, L., Coutinho, M. L.,… and Gaspar, D. (2018). “Landmark of the past in the Antequera megalithic landscape: a multi-disciplinary approach to the Matacabras rock art shelter”. Journal of Archaeological Science, 95, pp. 76-93. DOI: https://doi.org/10.1016/j.jas.2018.05.005.) and specific discoveries providing empirical backing to long-held hypotheses, such as the association of engraved stelae to pathways and burials (Rivera Jiménez et al., 2021Rivera Jiménez, T., García Sanjuán, L., Díaz-Guardamino, M., Donaire Romero, T., Morales González, J. A., Lozano Rodríguez, J. A.,… and Aguilera Collado, E. (2021). “The Cañaveral de León stela (Huelva, Spain). A monumental sculpture in a landscape of settlements and pathways”. Journal of Archaeological Science: Reports, 40 (A), 103251. DOI: https://doi.org/10.1016/j.jasrep.2021.103251.Rivera Jiménez, T., García Sanjuán, L., Díaz-Guardamino, M., Donaire Romero, T., Morales González, J. A., Lozano Rodríguez, J. A.,… and Aguilera Collado, E. (2021). “The Cañaveral de León stela (Huelva, Spain). A monumental sculpture in a landscape of settlements and pathways”. Journal of Archaeological Science: Reports, 40 (A), 103251. DOI: https://doi.org/10.1016/j.jasrep.2021.103251.; García Sanjuán et al., 2025García Sanjuán, L., Rivera-Jiménez, T., Díaz-Guardamino, M., Wheatley, D., Lozano Rodríguez, J. A., Donaire Romero, T.,… and Bailiff, I. (2025). “Shedding new light on the context and temporality of Iberian warrior stelae: The Cañaveral de León 2 Stela and Las Capellanías burial complex (Huelva, SW Spain)”. PLoS ONE, 20 (4), e0321080. DOI: https://doi.org/10.1371/journal.pone.0321080.García Sanjuán, L., Rivera-Jiménez, T., Díaz-Guardamino, M., Wheatley, D., Lozano Rodríguez, J. A., Donaire Romero, T.,… and Bailiff, I. (2025). “Shedding new light on the context and temporality of Iberian warrior stelae: The Cañaveral de León 2 Stela and Las Capellanías burial complex (Huelva, SW Spain)”. PLoS ONE, 20 (4), e0321080. DOI: https://doi.org/10.1371/journal.pone.0321080.). Therefore, the re-examination of sites published long ago can lead to improved results and a new understanding of graphical techniques, chronologies and traditions.

In this paper, we present one such case. Discovered more than thirty years ago (Iglesias García et al., 1992Iglesias García, L., Queipo de Llano Martínez, G. and Chacón Cano, J. M. (1992). “Grabadores (sic) rupestres inéditos en el Cerro del Riscal (El Madroño, Sevilla)”. SPAL, 1, pp. 209-218. DOI: https://doi.org/10.12795/spal.1992.i1.10.Iglesias García, L., Queipo de Llano Martínez, G. and Chacón Cano, J. M. (1992). “Grabadores (sic) rupestres inéditos en el Cerro del Riscal (El Madroño, Sevilla)”. SPAL, 1, pp. 209-218. DOI: https://doi.org/10.12795/spal.1992.i1.10.; Chacón Cano et al., 1995Chacón Cano, J. M., Iglesias García, L. and Queipo de Llano, G. (1995). “Petroglifos: aproximación a la interpretación. El modelo Riscal”. Trabalhos de Antropologia e Etnologia, 35 (3), pp. 269-286.Chacón Cano, J. M., Iglesias García, L. and Queipo de Llano, G. (1995). “Petroglifos: aproximación a la interpretación. El modelo Riscal”. Trabalhos de Antropologia e Etnologia, 35 (3), pp. 269-286.), the site of El Riscal stands today as the only rock art station known in the province of Seville (Andalusia, Spain), a territory otherwise very rich in late prehistoric archaeological remains. Located near the village of El Madroño, in the northwestern area of the Seville province (Fig. 1), El Riscal is located at 368 masl (Fig. 2), crowned by a 3rd class survey point, very near the boundary with the province of Huelva.

From a geomorphological perspective, the hill top is a ‘tor’-like rocky outcrop with huge boulders exhibiting ruiniform morphology (Migoń et al., 2017Migoń, P., Duszyński, F. and Goudie, A. (2017). “Rock cities and ruiniform relief: Forms–processes–terminology”. Earth-Science Reviews, 171, pp. 78-104. DOI: https://doi.org/10.1016/j.earscirev.2017.05.012.Migoń, P., Duszyński, F. and Goudie, A. (2017). “Rock cities and ruiniform relief: Forms–processes–terminology”. Earth-Science Reviews, 171, pp. 78-104. DOI: https://doi.org/10.1016/j.earscirev.2017.05.012.) mainly due to thermoclasty. Geologically, the site is located in the South Portuguese Zone, within the Iberian Massif (Fig. 1A). This large palaeogeographic area extends from the Ossa-Morena Zone in the north, to the most recent formations of the Guadalquivir basin in the south. It presents rocks ranging from the Middle Devonian to the Permian and is divided into five palaeogeographic domains, namely 1) Pulo de Lobo Domain; 2) the Iberian Pyrite Belt; 3) the Southwest Portuguese Domain; 4) the Sierra Norte Batholith and 5) the Permian Viar Basin (Fig. 1B).

The Iberian Pyrite Belt (IPB) is located in the central part of the South Portuguese Zone, within a pull-apart intracontinental marine basin filled by a sequence of predominantly felsic volcanic rocks with abundant siliciclastic intercalations, deposited on a shallow marine platform sequence (Conde Rivas, 2016Conde Rivas, C. (2016). Geology and hydrothermal evolution of massive sulphides of the Iberian Pyrite Belt, Spain. PhD thesis dissertation. Salamanca: IGME/University of Salamanca: 377. Available at: https://gredos.usal.es/bitstream/handle/10366/133189/REDUCIDA_GeologiaEvolucionHidrotermal.pdf?sequence=1&isAllowed=y.Conde Rivas, C. (2016). Geology and hydrothermal evolution of massive sulphides of the Iberian Pyrite Belt, Spain. PhD thesis dissertation. Salamanca: IGME/University of Salamanca: 377. Available at: https://gredos.usal.es/bitstream/handle/10366/133189/REDUCIDA_GeologiaEvolucionHidrotermal.pdf?sequence=1&isAllowed=y.). The IPB is divided into the Phyllite-Quartzite Group (PQ Group) (Med.-Upper Famenian); Volcanic-Sedimentary Complex (VSC) (Upper Famenian-Middle Visean) and Flysch-type Sequence (Culm Group) (Upper Visean) (Fig. 1B).

The VSC is composed of two felsic subunits separated by a massive black shale sulfide horizon. The lower subunit shows pyroclastic features, consisting of dacitic crystalline and vitric tuffs interbedded with a sequence of volcanic shales. The upper subunit is composed of dacite sills, domes and volcaniclastic deposits with subordinate rhyolitic sills and cryptodomes, and rare basic volcanics (Almodóvar et al., 1998Almodóvar, G. R., Sáez, R., Pons, J. M., Maestre, A., Toscano, M. and Pascual, E. (1998). “Geology and genesis of the Aznalcóllar massive sulfide deposits, Iberian Pyrite Belt, Spain”. Mineralium Deposita, 33, pp. 111-136. DOI: https://doi.org/10.1007/s001260050136.Almodóvar, G. R., Sáez, R., Pons, J. M., Maestre, A., Toscano, M. and Pascual, E. (1998). “Geology and genesis of the Aznalcóllar massive sulfide deposits, Iberian Pyrite Belt, Spain”. Mineralium Deposita, 33, pp. 111-136. DOI: https://doi.org/10.1007/s001260050136.). The northern sector of the Pyrite Belt (volcanic sequence), presents a stratigraphic sequence that includes an important basal andesite unit followed by basalt flows and intrusions in sedimentary intercalations and two felsic dome-roof units (Conde Rivas, 2016Conde Rivas, C. (2016). Geology and hydrothermal evolution of massive sulphides of the Iberian Pyrite Belt, Spain. PhD thesis dissertation. Salamanca: IGME/University of Salamanca: 377. Available at: https://gredos.usal.es/bitstream/handle/10366/133189/REDUCIDA_GeologiaEvolucionHidrotermal.pdf?sequence=1&isAllowed=y.Conde Rivas, C. (2016). Geology and hydrothermal evolution of massive sulphides of the Iberian Pyrite Belt, Spain. PhD thesis dissertation. Salamanca: IGME/University of Salamanca: 377. Available at: https://gredos.usal.es/bitstream/handle/10366/133189/REDUCIDA_GeologiaEvolucionHidrotermal.pdf?sequence=1&isAllowed=y.). In the study area, andesites appear, overlying the alternation of slates, silstones, meta-sandstones and quartzites and underlying the basalts with levels of black slates with radiolarians (Fig. 1C).

Today, El Riscal hill is covered by Mediterranean vegetation dominated by Quercineae (Quercus ilex, Q. suber, Q. rotundifolia) and Cistaceae (Cistus ladanifer, C. salviifolius). The Cistaceae, particularly, cover densely the terrain, and following the spring rains, access to the rock art station is rendered difficult. The boulders compose a sheltered structure, a “Poor Man’s Cave” of sorts (Chacón Cano et al., 1995Chacón Cano, J. M., Iglesias García, L. and Queipo de Llano, G. (1995). “Petroglifos: aproximación a la interpretación. El modelo Riscal”. Trabalhos de Antropologia e Etnologia, 35 (3), pp. 269-286.Chacón Cano, J. M., Iglesias García, L. and Queipo de Llano, G. (1995). “Petroglifos: aproximación a la interpretación. El modelo Riscal”. Trabalhos de Antropologia e Etnologia, 35 (3), pp. 269-286.), with inner and outer spaces in which some of the surfaces were engraved. The first publication of the site (Iglesias García et al., 1992Iglesias García, L., Queipo de Llano Martínez, G. and Chacón Cano, J. M. (1992). “Grabadores (sic) rupestres inéditos en el Cerro del Riscal (El Madroño, Sevilla)”. SPAL, 1, pp. 209-218. DOI: https://doi.org/10.12795/spal.1992.i1.10.Iglesias García, L., Queipo de Llano Martínez, G. and Chacón Cano, J. M. (1992). “Grabadores (sic) rupestres inéditos en el Cerro del Riscal (El Madroño, Sevilla)”. SPAL, 1, pp. 209-218. DOI: https://doi.org/10.12795/spal.1992.i1.10.) revealed seven engraved panels (designated as CR1-CR7), arranged in several parts of the shelter. After that publication, the same authors (Chacón Cano et al., 1995Chacón Cano, J. M., Iglesias García, L. and Queipo de Llano, G. (1995). “Petroglifos: aproximación a la interpretación. El modelo Riscal”. Trabalhos de Antropologia e Etnologia, 35 (3), pp. 269-286.Chacón Cano, J. M., Iglesias García, L. and Queipo de Llano, G. (1995). “Petroglifos: aproximación a la interpretación. El modelo Riscal”. Trabalhos de Antropologia e Etnologia, 35 (3), pp. 269-286.) redefined the engravings as belonging to three groups, basically two decontextualized ones (CR1 and CR7), and one group including the rest, although no graphical illustration of the panels were provided.

The purpose of this paper is to present new research, based on a multidisciplinary approach and non-invasive methods, aimed at providing a new understanding of the El Riscal engravings. The results lead not just to a greatly improved record of the engraved surfaces and motifs in themselves, but also to a new analysis and assessment of a little-known rock art style that has hardly ever been documented in southern Iberia.

2. METHODS  ⌅

The multi-method approach followed in this study was intended to a) enhance the visual record of the motifs; b) detect possible painted areas and characterize possible pigments; c) generate new contextual renderings of the engravings in order to produce updated tracings suitable for a spatial analysis; d) analyse the archaeoastronomical dimension of the site, and e) provide archaeological background through archaeological survey of the immediate surroundings.

2.1. Petrology

Rock samples from areas near the engravings were analysed both macro- and microscopically through thin sections under parallel and crossed nicols, using a petrographic microscope to characterize the rocks on which the engravings were made.

2.2. 3D Models

A complete reconstruction of the geometry of the site was considered of crucial importance, especially because most engravings were widely deteriorated due to weathering and forest fires —about 30 wild fires were counted in the surrounding area between 2004 and 2019¹1 Ecologistas en Acción (2019). Llevan tres años intentando quemar El Madroño y al final lo han conseguido [on line: https://www.ecologistasenaccion.org/125739/llevan-tres-anos-intentando-quemar-el-madrono-y-al-final-lo-han-conseguido/].. The photogrammetric model of the panels was obtained from photographs taken with a DSLR Olympus E520 camera with a 14-45 mm Olympus Zuiko digital objective (10 MP, f/3.5, 5.6) and an iPhone 12 mini (12 MP, f/1.6, effective focal length 26 mm) for the narrowest areas. The use of mobile phones as a recording tool has demonstrated enough accuracy and efficiency for close range photogrammetry (El-Din Fawzy, 2015El-Din Fawzy, H. (2015). “The accuracy of mobile phone camera instead of high-resolution camera in digital close range photogrammetry”. International Journal of Civil Engineering and Technology, 6 (1), pp. 76-85.El-Din Fawzy, H. (2015). “The accuracy of mobile phone camera instead of high-resolution camera in digital close range photogrammetry”. International Journal of Civil Engineering and Technology, 6 (1), pp. 76-85.; Adamopoulos et al., 2021Adamopoulos, E., Rinaudo, F. and Ardissono, L. (2021). “A Critical Comparison of 3D Digitization Techniques for Heritage Objects”. ISPRS International Journal of Geo-Information, 10, p. 10. DOI: https://doi.org/10.3390/ijgi10010010.Adamopoulos, E., Rinaudo, F. and Ardissono, L. (2021). “A Critical Comparison of 3D Digitization Techniques for Heritage Objects”. ISPRS International Journal of Geo-Information, 10, p. 10. DOI: https://doi.org/10.3390/ijgi10010010.). The 3D models were obtained by means of Agisoft Metashape Standard Edition (v. 1.7.3) software package. The digitized engravings were also studied under different shaders from the free software package MeshLab (v.2022.02). This tool allows the application of filters in order to highlight morphological characteristics, as well as adjusting the direction and light intensity for an instantaneous highlight of the concavities and convexities of the rock surface.

2.3. Digital image analysis

The panels were documented by means of a Canon EOS 450D digital camera (12 MP, f/4, focal length 18 mm) for digital image analysis with the aim of identifying areas where pigments were possibly present. Additionally, IR photographs of the reddish panels were also taken by means of a modified Olympus E-500 DSLR camera (extraction of the optical low-pass filters) with two band-pass filters of 850 and 950 nm (Zomei) individually mounted over the lens of the camera. This photographic mode required long exposures. Several Digital Image Analysis techniques were used in order to clarify the elements represented in the engravings. In addition, decorrelation of images by Principal Components Analysis (PCA) (Gillespie et al., 1986Gillespie, A. R., Kahle, A. B. and Walker, R. E. (1986). “Color enhancement of highly correlated images. I. Decorrelation and HSI contrast stretches”. Remote Sensing of Environment, 20, pp. 209‐235. DOI: https://doi.org/10.1016/0034-4257(86)90044-1.Gillespie, A. R., Kahle, A. B. and Walker, R. E. (1986). “Color enhancement of highly correlated images. I. Decorrelation and HSI contrast stretches”. Remote Sensing of Environment, 20, pp. 209‐235. DOI: https://doi.org/10.1016/0034-4257(86)90044-1.; Rogerio-Candelera, 2015aRogerio-Candelera, M. A. (2015a). “Digital image analysis based study, recording, and protection of painted rock art. Some Iberian experiences”. Digital Applications in Archaeology and Cultural Heritage, 2, pp. 68-78. DOI: https://doi.org/10.1016/j.daach.2014.11.001.Rogerio-Candelera, M. A. (2015a). “Digital image analysis based study, recording, and protection of painted rock art. Some Iberian experiences”. Digital Applications in Archaeology and Cultural Heritage, 2, pp. 68-78. DOI: https://doi.org/10.1016/j.daach.2014.11.001.), elaboration of false colour images, as well as contrast stretch of images in HSI colour model (HSI-CS) and application of indexes for the detection of possible ferric pigments (Rivera Jiménez et al., 2021Rivera Jiménez, T., García Sanjuán, L., Díaz-Guardamino, M., Donaire Romero, T., Morales González, J. A., Lozano Rodríguez, J. A.,… and Aguilera Collado, E. (2021). “The Cañaveral de León stela (Huelva, Spain). A monumental sculpture in a landscape of settlements and pathways”. Journal of Archaeological Science: Reports, 40 (A), 103251. DOI: https://doi.org/10.1016/j.jasrep.2021.103251.Rivera Jiménez, T., García Sanjuán, L., Díaz-Guardamino, M., Donaire Romero, T., Morales González, J. A., Lozano Rodríguez, J. A.,… and Aguilera Collado, E. (2021). “The Cañaveral de León stela (Huelva, Spain). A monumental sculpture in a landscape of settlements and pathways”. Journal of Archaeological Science: Reports, 40 (A), 103251. DOI: https://doi.org/10.1016/j.jasrep.2021.103251.) were employed too.

2.4. Pigment characterisation

Six micro-samples were taken in order to examine the suspected presence of pigments in some of the engravings, in the framework of the contract Inventario y documentación del arte rupestre de Huelva. Megalitos y otros (2021 0000667050), Junta de Andalucía (Tab. 1). All the extracted samples were studied by X-ray diffraction (XRD) in order to obtain information about their mineralogical composition. The XRD analyses were carried out at Geosciences Barcelona (GEO3BCN-CSIC) by means of a Bruker D8-A25 diffractometer equipped with a Cu X-ray source (CuKα radiation) and a LynxEye position sensitive detector. Measurements were performed by using low-background silicon sample holders, employing large integration times in order to improve the signal-to-noise ratio. Phase identification was carried out by using the DIFFRAC.EVA software in combination with the Powder Diffraction File (PDF-2) and the Crystallography Open Database (COD). Secondary electron microscopy (SEM) images at different magnifications were also acquired in medium-vacuum by using the backscattered electron detector (BSD) of a Hitachi TM4000Plus desktop microscope at GEO3BCN-CSIC. A Bruker Quantax energy dispersive (EDS) X-ray spectrometer was used for elemental analysis of the micro-samples.

2.5. Archaeological survey

On 8th October 2023, an intensive archaeological survey was conducted as part of a comprehensive review of the site. A team of five surveyors undertook the survey with the aim of identifying potential surface remains of material culture that could assist in understanding the chronology of the rock engravings. The search was performed within a range of 50 m around the location of the engravings, along two sessions of 90 minutes, on the north and south of the engravings, respectively, thus totalling 3 hours of work. Prospectors were spaced a maximum of 1-1.5 m apart and conducted a thorough surface inspection, scraping the topsoil at random locations, and removing surface vegetation and soil in order to increase the visibility of possible material remains.

2.6. Archaeoastronomy

Data for archaeoastronomical analysis were also taken on 8th October 2023. The azimuth data were obtained with a professional compass (SUUNTO 360-R), and thereafter corrected for magnetic declination effects. Such measurements have an accuracy of ¼º. The horizon height measurements were acquired with a professional clinometer of the same brand, with ⅓º accuracy.

3. RESULTS  ⌅

3.1. Petrological description

Under naked-eye conditions, the rocks at El Riscal have a reddish colour due to surface alteration caused by weathering (Fig. 3A). In fresh section, the rock exhibits a phaneritic texture, characterised by the presence of predominantly melanocratic phenocrystals. These crystals, measuring up to 3 mm, are embedded within a light-coloured, greyish leucocratic matrix (Fig. 3B). Under the petrographic microscope, the rock has a porphyritic-seriate and massive aphanitic texture that ranges from holocrystalline to hypocrystalline. The main mineral association is made up of phenocrystals, mostly of subidiomorphic plagioclase (0.1-4 mm), augite (altered to chlorite), amphibole and iron oxides. Calcic plagioclases (mainly labradorite) show a clear alteration to quartz, epidote, clinozoisite and sometimes sericite in many of their crystals, probably under a regional pre-Variscan hydrothermal environment (Barriga, 1990Barriga, F. J. A. S. (1990). “Metallogenesis in the Iberian Pyrite Belt”. In: Dallmeyer, R. D. and Martínez García, E. (Eds.). Pre-Mesozoic Geology of Iberia. Berlin: Springer, pp. 369-379. DOI: https://doi.org/10.1007/978-3-642-83980-1_26.Barriga, F. J. A. S. (1990). “Metallogenesis in the Iberian Pyrite Belt”. In: Dallmeyer, R. D. and Martínez García, E. (Eds.). Pre-Mesozoic Geology of Iberia. Berlin: Springer, pp. 369-379. DOI: https://doi.org/10.1007/978-3-642-83980-1_26.; Munhà, 1990Munhà, J. (1990). “Metamorphic evolution of the South Portuguese/Pulo do Lobo Zone”. In: Dallmeyer, R. D. and Martínez García, E. (Eds.). Pre-Mesozoic Geology of Iberia. Berlin: Springer, pp. 363-368.Munhà, J. (1990). “Metamorphic evolution of the South Portuguese/Pulo do Lobo Zone”. In: Dallmeyer, R. D. and Martínez García, E. (Eds.). Pre-Mesozoic Geology of Iberia. Berlin: Springer, pp. 363-368.; Sáez et al., 1999Sáez, R., Pascual, E., Toscano, M. and Almodóvar, G. R. (1999). “The Iberian type of volcano-sedimentary massive sulphide deposits”. Mineralium Deposita, 34, pp. 549-570. DOI: https://doi.org/10.1007/s001260050220.Sáez, R., Pascual, E., Toscano, M. and Almodóvar, G. R. (1999). “The Iberian type of volcano-sedimentary massive sulphide deposits”. Mineralium Deposita, 34, pp. 549-570. DOI: https://doi.org/10.1007/s001260050220.). Metallic ore and rutile were observed inside the plagioclases and augites at the edges. Some volcanic glass and microliths of plagioclase, augite, quartz, metallic ore, rutile and titanite were observed in the matrix (Fig. 3 C-F). Microvesicles measuring up to 1.5 mm were also recorded. These were irregularly distributed and exhibited quartz regrowth in an atoll texture. They were also filled with epidote and even clinozoisite (Fig. 3 C-D). When the texture becomes microcrystalline, the sericite-quartz association prevails along with epidote-chlorite zones (Fig. 3 C-D). The petrographic composition of these lavas is andesitic. Andesite is an igneous rock, meaning it is not malleable or deformable by attrition. However, under intense friction, it tends to fragment or flake. Due to its mineralogy and seriated porphyritic and massive aphanitic texture, andesite possesses medium-high hardness and moderate to high abrasion resistance. It is hard and highly resistant to scratching, requiring the use of controlled abrasives such as flint to be worn.

3.2. The engravings

3.2.1. Location and distribution

The first task involved the identification of the different panels, as described in Iglesias García et al. (1992Iglesias García, L., Queipo de Llano Martínez, G. and Chacón Cano, J. M. (1992). “Grabadores (sic) rupestres inéditos en el Cerro del Riscal (El Madroño, Sevilla)”. SPAL, 1, pp. 209-218. DOI: https://doi.org/10.12795/spal.1992.i1.10.Iglesias García, L., Queipo de Llano Martínez, G. and Chacón Cano, J. M. (1992). “Grabadores (sic) rupestres inéditos en el Cerro del Riscal (El Madroño, Sevilla)”. SPAL, 1, pp. 209-218. DOI: https://doi.org/10.12795/spal.1992.i1.10.), in addition to the search for other potential, hitherto undetected motifs. The nature of the published tracings was found to be deficient in a number of ways, including the following: (i) lack of a general plan; (ii) rather fragmentary recording (only a detail of each panel was reported); (iii) low-quality hand-made naked-eye renderings of the motifs; (iv) lack of a clear key for interpreting the published drawings; (v) diverging orientations for each of the panels. In order to avoid future misunderstandings, the same designation system followed in that paper has been adopted here.

At first, it was impossible to find panel CR1, described as “three associated circles engraved over a small square rock of approximately 64 × 30 cm, clearly in secondary position and decontextualized with regards to the rest of the groups of engravings”²2 This is our translation.. Fortunately, after some enquiries, the engraved stone was found in the near-by Riotinto Mining Museum (Huelva, Spain). Since the early 1980’s CR1 has been housed in the Riotinto Museum. Consequently, the first publishers of the shelter did not observe this element in situ, although this fact was not noted. CR2, CR3 and CR4 were relatively easy to find (though the published tracings were partial and showed an orientation different to the real one), as they were placed in adjacent rocks of the shelter (Fig. 4). These panels, in particular CR2 and CR3, exhibiting the highest number of graphic elements are the most remarkable of the site. Locating panel CR5 proved to be more problematic than expected. After a fruitless search of all the sheltered rock structure, we reached the conclusion that what was designated by Iglesias García et al. (1992Iglesias García, L., Queipo de Llano Martínez, G. and Chacón Cano, J. M. (1992). “Grabadores (sic) rupestres inéditos en el Cerro del Riscal (El Madroño, Sevilla)”. SPAL, 1, pp. 209-218. DOI: https://doi.org/10.12795/spal.1992.i1.10.Iglesias García, L., Queipo de Llano Martínez, G. and Chacón Cano, J. M. (1992). “Grabadores (sic) rupestres inéditos en el Cerro del Riscal (El Madroño, Sevilla)”. SPAL, 1, pp. 209-218. DOI: https://doi.org/10.12795/spal.1992.i1.10.) as CR5 corresponded to the lower-right part of CR2, as this panel appeared to be ‘interrupted’ by a large boulder that had fallen from the roof of the shelter (Fig. 5).

Panel CR6 was readily identifiable due to its location within the innermost part of the shelter, situated within a crevice set by the largest boulders over CR3 and CR4, which covers other surrounding blocks. These fallen blocks configure an approximately piriform cavity which is easily accessible from the outside. There are two other communications with the exterior, one of them practicable and the other one presenting engravings. The published description mentioned two circular elements, designated as A and B. In our review, we found two different things. Firstly, CR6a, a panel featuring at least two engraved circles (coincident with CR6 A and B of Iglesias García et al., 1992Iglesias García, L., Queipo de Llano Martínez, G. and Chacón Cano, J. M. (1992). “Grabadores (sic) rupestres inéditos en el Cerro del Riscal (El Madroño, Sevilla)”. SPAL, 1, pp. 209-218. DOI: https://doi.org/10.12795/spal.1992.i1.10.Iglesias García, L., Queipo de Llano Martínez, G. and Chacón Cano, J. M. (1992). “Grabadores (sic) rupestres inéditos en el Cerro del Riscal (El Madroño, Sevilla)”. SPAL, 1, pp. 209-218. DOI: https://doi.org/10.12795/spal.1992.i1.10.). Secondly, what we designated as CR6b, a motif that is difficult to appreciate and is carved in the bottom of a natural narrow crevice left by fallen blocks, which communicates the inner chamber with the exterior (Fig. 6).

As a supporting method in the visual analysis of the petroglyphs, the digitized motifs were also studied by means of different shaders with Meshlab. This digital processing tool was instrumental in distinguishing the intentionally carved and abraded motifs from those produced by weathering. Particularly, the Radiance Scaling shader, with final graphic results quite similar to those produced by Reflectance Transformation Imaging (Carrero-Pazos et al., 2016Carrero-Pazos, M., Vázquez-Martínez, A. and Vilas-Estévez, B. (2016). “AsTrend: Towards a new method for the study of ancient carvings”. Journal of Archaeological Science: Reports, 9, pp. 105-119. DOI: https://doi.org/10.1016/j.jasrep.2016.06.044.Carrero-Pazos, M., Vázquez-Martínez, A. and Vilas-Estévez, B. (2016). “AsTrend: Towards a new method for the study of ancient carvings”. Journal of Archaeological Science: Reports, 9, pp. 105-119. DOI: https://doi.org/10.1016/j.jasrep.2016.06.044.; López-Menchero Bendicho et al., 2017López-Menchero Bendicho, V. M., Marchante Ortega, Á., Vincent, M., Cárdenas Martín-Buitrago, Á. J. and Onrubia Pintado, J. (2017). “Uso combinado de la fotografía digital nocturna y de la fotogrametría en los procesos de documentación de petroglifos: el caso de Alcázar de San Juan (Ciudad Real, España)”. Virtual Archaeology Review, 8 (17), pp. 64-74. DOI: https://doi.org/10.4995/var.2017.6820.López-Menchero Bendicho, V. M., Marchante Ortega, Á., Vincent, M., Cárdenas Martín-Buitrago, Á. J. and Onrubia Pintado, J. (2017). “Uso combinado de la fotografía digital nocturna y de la fotogrametría en los procesos de documentación de petroglifos: el caso de Alcázar de San Juan (Ciudad Real, España)”. Virtual Archaeology Review, 8 (17), pp. 64-74. DOI: https://doi.org/10.4995/var.2017.6820.), allowed a detailed assessment of the peculiarities of the rock surface (Annex 1 - Fig. S1).

3.2.2. Description of the panels

Panel CR1 shows a composition of three tangent circular forms arranged vertically. One of them (the central one) consists of at least three concentric circles (Fig. 7A). The engravings have a U-shaped section and a thickness ranging from 2 to 4 cm. The panel is in relative good state of preservation, likely due to its long-term storage at the Riotinto Museum, where it has been spared for almost half a century of weathering and other factors, including frequent wild fires.

Panel CR2, located in the north face of the outcrop, comprises a complex ensemble of at least 80 circular motifs arranged in a kind of horror vacui, where some circles cut others (Fig. 7B). The poor state of preservation of this set of engravings does not allow to elucidate if there are superimpositions between the motifs. The inter-cutting and super-imposition of the motifs may be indicative of ‘maintenance’, updating and re-interpretation of the panel, resulting from persistent use over time. The inter-cutting suggests that, far from being something ‘finished’, the set of engravings was envisaged and used as an ‘alive’ entity, with newly-made circular motifs cutting pre-existing ones, which were almost invisible.

Panel CR3, situated in the NW face of the rocky outcrop, portrays a totally different picture compared to the preceding two panels. In contrast to the accumulation of circular shapes of CR1 and CR2, CR3 shows a series of linear engravings with a V-shaped section that form reticular or grid-like designs of different lengths (Fig. 7C). In addition to the grids, CR3 shows at least three circles associated with straight lines, as well as other approximately circular elements which are more problematic to interpret. Due to its exposure to weathering and runoff water, CR3 is very deteriorated and most of the motifs are difficult to read, so the use of Meshlab shaders was essential to obtain an acceptable graphic rendering. In the lower area, the panel shows modern graffiti consisting of several letters of the Latin alphabet, engraved with a metal tool.

These are much better preserved than the pre-existing reticular motifs, to which they are superimposed. The presence of modern graffiti is well attested on the shelter. In addition to the previously mentioned example, another instance was found on the exterior surface of the rocky outcrop, which exhibits a cross and a date: 29 N 93 (Annex 1 - Fig. S2), as well as what appeared to be an engraved letter ‘E’ at the point of a knife, along with several possible cup-marks on the lichen layer that covered another rock in the upper area of the outcrop (Annex 1 - Fig. S3).

Located very close to CR3, and with the same orientation (NW face of the outcrop), CR4 has a similar appearance, although without the presence of circular motifs (Fig. 7D). It is a set of V-section engravings that define reticular motifs, which have a reddish colour on their surface (Fig. 3A). More protected from weathering than CR3, the lines are easier to recognise and follow than in the previous panel.

Regarding panel CR6, it is located in the inner ‘chamber’ of the outcrop, facing the NE wall. The original publication by Iglesias García et al. (1992Iglesias García, L., Queipo de Llano Martínez, G. and Chacón Cano, J. M. (1992). “Grabadores (sic) rupestres inéditos en el Cerro del Riscal (El Madroño, Sevilla)”. SPAL, 1, pp. 209-218. DOI: https://doi.org/10.12795/spal.1992.i1.10.Iglesias García, L., Queipo de Llano Martínez, G. and Chacón Cano, J. M. (1992). “Grabadores (sic) rupestres inéditos en el Cerro del Riscal (El Madroño, Sevilla)”. SPAL, 1, pp. 209-218. DOI: https://doi.org/10.12795/spal.1992.i1.10.) reported two circles with a diameter of approximately 24 cm (although only one was included in the drawings). However, three circular motifs were observed, two of which were composed of more or less concentric circles (Fig. 7E). These are U-section engraved motifs, as is the case with the other engravings of circular elements in this shelter.

Finally, at the end of a narrow crevice formed by the various blocks that constitute the shelter (Fig. 6), which opens immediately onto CR6a and is also oriented to NE, there is what we have designated CR6b. This panel, which remained unpublished, consists of a series of engravings of V-shaped reticular and linear motifs similar to CR3 and CR4 (Fig. 7F).

3.3. Digital Image Analysis (DIA)

The elaboration of pseudocolour images from the bands obtained by means of Principal Components Analysis allowed a significant improvement in the visibility of certain motifs (Annex 1 - Fig. S10, for instance), but, in general, due to the scarce differences in hue, the outcomes were poor when compared to those achieved through digital photogrammetrical methods.

The results of the application of a generic ferric pigments index (Sebastián López et al., 2013Sebastián López, M., Palomo Arroyo, M., Rincón Ramírez, J. A., Ormeño Villajos, S. and Vicent García, J. M. (2013). “Métodos de documentación, análisis y conservación no invasivos para el arte rupestre postpaleolítico: radiometría de campo e imágenes multiespectrales. Ensayos en la cueva del Tío Garroso (Alacón, Teruel)”. In: La Ciencia y el Arte IV. Ciencias experimentales y conservación del Patrimonio. Madrid: Ministerio de Educación, Cultura y Deporte, pp. 279-287.Sebastián López, M., Palomo Arroyo, M., Rincón Ramírez, J. A., Ormeño Villajos, S. and Vicent García, J. M. (2013). “Métodos de documentación, análisis y conservación no invasivos para el arte rupestre postpaleolítico: radiometría de campo e imágenes multiespectrales. Ensayos en la cueva del Tío Garroso (Alacón, Teruel)”. In: La Ciencia y el Arte IV. Ciencias experimentales y conservación del Patrimonio. Madrid: Ministerio de Educación, Cultura y Deporte, pp. 279-287.; Rogerio-Candelera, 2015bRogerio-Candelera, M. A. (2015b). “Métodos basados en el análisis digital de imágenes para el estudio del arte rupestre”. In: Estudio y Conservación del Patrimonio Cultural. Actas. Málaga: Universidad de Málaga, pp. 78-81.Rogerio-Candelera, M. A. (2015b). “Métodos basados en el análisis digital de imágenes para el estudio del arte rupestre”. In: Estudio y Conservación del Patrimonio Cultural. Actas. Málaga: Universidad de Málaga, pp. 78-81.; Rivera-Jiménez et al., 2021Rivera Jiménez, T., García Sanjuán, L., Díaz-Guardamino, M., Donaire Romero, T., Morales González, J. A., Lozano Rodríguez, J. A.,… and Aguilera Collado, E. (2021). “The Cañaveral de León stela (Huelva, Spain). A monumental sculpture in a landscape of settlements and pathways”. Journal of Archaeological Science: Reports, 40 (A), 103251. DOI: https://doi.org/10.1016/j.jasrep.2021.103251.Rivera Jiménez, T., García Sanjuán, L., Díaz-Guardamino, M., Donaire Romero, T., Morales González, J. A., Lozano Rodríguez, J. A.,… and Aguilera Collado, E. (2021). “The Cañaveral de León stela (Huelva, Spain). A monumental sculpture in a landscape of settlements and pathways”. Journal of Archaeological Science: Reports, 40 (A), 103251. DOI: https://doi.org/10.1016/j.jasrep.2021.103251.) following the equation [1] allowed us to remark what was, anyway, evident: that some elements presented a reddish coloration.

where FPI is the Ferric Pigments Index, ρ(i,R) is the set of pixel values corresponding to the Red band, and ρ(i,B) represents the set of pixel values of the Blue band in a RGB colour mode.

The goal of this visual analysis was to detect any potential patterns that might suggest the deliberate application of red pigment over the engravings (Annex 1 - Fig. S11). The results of this approach, although not unfavourable, did not reveal any hidden red remains, in contrast to the findings in other applications of these digital image analysis techniques (e. g., Rivera-Jiménez et al., 2021Rivera Jiménez, T., García Sanjuán, L., Díaz-Guardamino, M., Donaire Romero, T., Morales González, J. A., Lozano Rodríguez, J. A.,… and Aguilera Collado, E. (2021). “The Cañaveral de León stela (Huelva, Spain). A monumental sculpture in a landscape of settlements and pathways”. Journal of Archaeological Science: Reports, 40 (A), 103251. DOI: https://doi.org/10.1016/j.jasrep.2021.103251.Rivera Jiménez, T., García Sanjuán, L., Díaz-Guardamino, M., Donaire Romero, T., Morales González, J. A., Lozano Rodríguez, J. A.,… and Aguilera Collado, E. (2021). “The Cañaveral de León stela (Huelva, Spain). A monumental sculpture in a landscape of settlements and pathways”. Journal of Archaeological Science: Reports, 40 (A), 103251. DOI: https://doi.org/10.1016/j.jasrep.2021.103251.).

3.4. Pigment characterisation

XRD analyses were performed to characterise the composition of the host rocks and also to determine the possible origin of the reddish colours observed in some areas of the sampled panels. Figs. S4 and S6 (Annex 1) show XRD scans for the two samples from engraved areas that exhibit a reddish colour (CR2-1 and CR4-1, see Tab. 1). These two scans, as well as the scans from colourless materials (Annex 1 - Figs. S5 and S7), are dominated by strong peaks of quartz, which is the major mineral in these rocks. In addition, weak peaks from other accompanying minerals also showed up in the scans. Many of the identified phases can be attributed to the original rock: feldspars (albite, microcline), amphiboles (pargasite) as well as other minerals like epidote and clinochlore, which are likely rock-forming minerals of secondary origin. Other minor phases like gypsum were also identified in some of the investigated samples and may be attributed to surface alterations of the host rock.

In the case of the reddish sample CR2-1 in panel CR-2, the XRD scan exhibits a weak, broad peak that may be attributed to poorly-crystalline goethite, which might explain the colour of this sample. However, a similar peak was also observed in the colourless control sample (CR2-2). In contrast, the reddish materials of panel CR-4 (sample CR4-1) did not show any clear signal from goethite. Thus, this iron oxyhydroxide most likely appears due to a specific alteration of the minerals in panel CR-2 and can therefore be discarded as the compound responsible for the reddish colour observed across El Riscal. It is important to note that the rest of the identified phases cannot explain the reddish colours observed in the site. This is the case, for instance, of clinochlore, which typically exhibits a blackish-green colour and which is known to occur in some instances of green earth pigments. Other Fe-bearing minerals like pargasite or epidote are neither expected to account for the observed red colours.

In the case of CR8, a pigmented area not far from the engraved panels, pargasite is the only Fe-containing mineral that has been identified in the XRD scans, both in the pigmented and in the control samples (Annex 1 - Figs. S8-S9). The fact that these samples also show a red colouration points toward a natural origin for the observed pigmentation.

In late prehistoric Iberian rock art, paintings were usually made with hematite pigment (Roldán et al., 2016Roldán García, C., Villaverde Bonilla, V., Ródenas Marín, I. and Murcia Mascarós, S. (2016). “A Unique Collection of Palaeolithic Painted Portable Art: Characterization of Red and Yellow Pigments from the Parpalló Cave (Spain)”. PLoS ONE, 11 (10), e0163565. DOI: https://doi.org/10.1371/journal.pone.0163565.Roldán García, C., Villaverde Bonilla, V., Ródenas Marín, I. and Murcia Mascarós, S. (2016). “A Unique Collection of Palaeolithic Painted Portable Art: Characterization of Red and Yellow Pigments from the Parpalló Cave (Spain)”. PLoS ONE, 11 (10), e0163565. DOI: https://doi.org/10.1371/journal.pone.0163565.), which could be of natural origin or the product of a thermic treatment of goethite and other ‘ochres’ (Perinet and Onoratini, 1987Perinet, G. and Onoratini, G. (1987). “À propos des colorants rouges préhistoriques: la présence d’hématite désordonnée est bien l’indice qu’ils on eté obtenus par cuisson de goethite”. Revue d’Archéometrie, 11, pp. 49-51. DOI: https://doi.org/10.3406/arsci.1987.1237.Perinet, G. and Onoratini, G. (1987). “À propos des colorants rouges préhistoriques: la présence d’hématite désordonnée est bien l’indice qu’ils on eté obtenus par cuisson de goethite”. Revue d’Archéometrie, 11, pp. 49-51. DOI: https://doi.org/10.3406/arsci.1987.1237.). In the case of El Riscal, the XRD scans did not reveal the presence of hematite in any of the investigated samples. This result was also confirmed with additional SEM-EDS analyses performed on these samples, which did not allow us to identify any clear signal of hematite.

Given the absence of iron oxide-based pigments, a possible explanation for the observed red colour in some of the El Riscal surfaces is rubefaction due to weathering or wild fires. It has been attested that, in soils, the hue reddens with increasing temperature, particularly over the range 300-500 ºC, which is a consequence of the transformation of iron hydrous oxides first into maghemite and then into hematite (Terefe et al., 2008Terefe, T., Mariscal-Sancho, I., Peregrina, F. and Espejo, R. (2008). “Influence of heating on various properties of six Mediterranean soils. A laboratory study”. Geoderma, 143, pp. 273-280. DOI: https://doi.org/10.1016/j.geoderma.2007.11.018.Terefe, T., Mariscal-Sancho, I., Peregrina, F. and Espejo, R. (2008). “Influence of heating on various properties of six Mediterranean soils. A laboratory study”. Geoderma, 143, pp. 273-280. DOI: https://doi.org/10.1016/j.geoderma.2007.11.018., quoting Taylor and Schwertmann, 1974Taylor, R. M. and Schwertmann, U. (1974). “Maghemite in soils and its origins I: properties and observations on soil maghemites”. Clay Minerals, 10, pp. 289-298. DOI: https://doi.org/10.1180/claymin.1974.010.4.07.Taylor, R. M. and Schwertmann, U. (1974). “Maghemite in soils and its origins I: properties and observations on soil maghemites”. Clay Minerals, 10, pp. 289-298. DOI: https://doi.org/10.1180/claymin.1974.010.4.07.; Mullins, 1977Mullins, C. E. (1977). “Magnetic susceptibility of the soil and its significance to soil science: a review”. Journal of Soil Science, 28, pp. 139-158. DOI: https://doi.org/10.1111/j.1365-2389.1977.tb02232.x.Mullins, C. E. (1977). “Magnetic susceptibility of the soil and its significance to soil science: a review”. Journal of Soil Science, 28, pp. 139-158. DOI: https://doi.org/10.1111/j.1365-2389.1977.tb02232.x.; Cornell and Schwertmann, 2003Cornell, R. M. and Schwertmann, U. (2003). The Iron Oxides: Structure, Properties, Reactions, Occurrence and Uses. Berlin: Wiley. DOI: https://doi.org/10.1002/3527602097.Cornell, R. M. and Schwertmann, U. (2003). The Iron Oxides: Structure, Properties, Reactions, Occurrence and Uses. Berlin: Wiley. DOI: https://doi.org/10.1002/3527602097.). Remarkably, rubefaction processes might have given rise to hematite coatings that would be hard to detect by XRD or SEM-EDS, at least with the present experimental conditions and set ups. This situation would be similar to the case of red soils which, as shown by Torrent et al. (1983Torrent, J., Schwertmann, U., Fechter, H. and Alférez, F. (1983). “Quantitative relationships between soil color and hematite content”. Soil Science, 136 (6), pp. 354-358.Torrent, J., Schwertmann, U., Fechter, H. and Alférez, F. (1983). “Quantitative relationships between soil color and hematite content”. Soil Science, 136 (6), pp. 354-358.), may exhibit a reddish colour due to the presence of hematite even in minimal amounts. In particular, poorly crystalline Fe oxides and hydroxides in nanoparticle form are ubiquitous in nature, and are responsible for the reddish coloration of many soils and rocks.

Nevertheless, the reddish colour of these samples might alternatively be attributed to the replacement of Si4+ by Fe3+ within the tetrahedral structure of quartz, the main mineral in these rocks (Liu et al., 2023Liu, C., Wang, W., Wang, H., Zhu, C. and Ren, B. (2023). “A review on removal of iron impurities from quartz mineral”. Minerals, 13, 1128. DOI: https://doi.org/10.3390/min13091128.Liu, C., Wang, W., Wang, H., Zhu, C. and Ren, B. (2023). “A review on removal of iron impurities from quartz mineral”. Minerals, 13, 1128. DOI: https://doi.org/10.3390/min13091128.). Such replacement could have been induced by the high-temperatures of a forest fire and would only require trace amounts of iron atoms that would not be detected by the analytical techniques used in this work. In order to confirm or discard this hypothesis, other experimental approaches beyond the scope of this work should be employed.

In summary, the El Riscal rocks show a great compositional and textural homogeneity, both in pigmented and unpigmented areas. S. Cassen et al. (2023Cassen S., Blank, M., Querré, G., Schulz-Paulsson, B., Vergès-Belmin, V. and Grimaud, V. (2023). Couleur du Temps. Altérations Chromatiques et Pseudo-Peintures Néolithiques Observées sur les Parois des Tombes Monumentales du Morbihan. Carnac. Nantes: Les Vaisseaux de Pierres, LARA / Nantes Université.Cassen S., Blank, M., Querré, G., Schulz-Paulsson, B., Vergès-Belmin, V. and Grimaud, V. (2023). Couleur du Temps. Altérations Chromatiques et Pseudo-Peintures Néolithiques Observées sur les Parois des Tombes Monumentales du Morbihan. Carnac. Nantes: Les Vaisseaux de Pierres, LARA / Nantes Université.) found the same problem of homogeneity in the results of the analyses of coloured and control samples when working with the orthostats of the megalithic tombs of Morbihan (France). This highlights the difficulty in determining the actual origin of the pigmentations in rock samples. Their interpretation of reddish areas in rock surfaces lie in the effects of wildfires, in the liberation of the iron contained in micaceous minerals due to the heating. This phenomenon is well attested experimentally in the cave of Chauvet (France) (Ferrier et al., 2014Ferrier, C., Debard, E., Kervazo, B., Brodard, A., Guibert, P., Baffier, D.,… and Maksud, F. (2014). “Les parois chaufées de la Grotte Chauvet-Pot d’Arc (Ardèche, France): charactérisation et chronologie”. PALEO, 25, pp. 59-78. DOI: https://doi.org/10.4000/paleo.2730.Ferrier, C., Debard, E., Kervazo, B., Brodard, A., Guibert, P., Baffier, D.,… and Maksud, F. (2014). “Les parois chaufées de la Grotte Chauvet-Pot d’Arc (Ardèche, France): charactérisation et chronologie”. PALEO, 25, pp. 59-78. DOI: https://doi.org/10.4000/paleo.2730.). In the case of El Riscal, more work would be required in order to unambiguously identify the origin of the observed red colours.

3.5. Archaeological context

On the southern face of the hill, with a steep slope that descends between the Pilón and Carrascal brooks, a triangular-shaped stone hammer, measuring 10 cm in length and 8 cm in maximum width (Fig. 8B), was identified alongside a knapped stone tool made of non-siliceous rock, with a retouched edge and a length of 3 cm. A small fragment of slate flake that does not appear naturally at the site was also identified. On the north face of the rocky outcrop on which the engravings are located, topographically a small plateau, a dozen small amorphous fragments of handmade pottery were located (Fig. 8A), as well as several fragments of wheel-made pottery, including glazed earthenware of modern or contemporary chronology.

Overall, although the amount of recovered material is small, and there is evidence of modern and/or contemporary frequentation (which may be related to the construction and maintenance of the survey point that crowns the hill, and which stands on a platform with a staircase made of stone and brick masonry) several of the artefacts found are compatible with a non-specific prehistoric chronology. The stone hammer and the hand-thrown pottery would not be out of place in a Neolithic or Copper Age site, although without more specific data it is impossible to provide greater precision to the chronology of the site and the rock art. No remains of what was previously described as a settlement built on terraces at the top and southern slope, adapted to the relief of the hill, with remains of huts built of branches covered with clay, and associated characteristic materials of the Copper Age (Linares Catela, 2011Linares Catela, J. A. (2011). Guía del Megalitismo de la Provincia de Huelva: Territorio, Paisaje y Arquitecturas Megalíticas. Sevilla: Junta de Andalucía.Linares Catela, J. A. (2011). Guía del Megalitismo de la Provincia de Huelva: Territorio, Paisaje y Arquitecturas Megalíticas. Sevilla: Junta de Andalucía., pp. 190-191), were found.

3.6. Archaeoastronomy

Tab. 2 shows the measurements obtained for the main panels with engraved motifs and the orientation of the main engraved areas. The orientations consist of the window of visibility as seen from the panels. Thus, the range in azimuths provides the extreme positions where the panel faces the horizon or a sky portion can be seen from them. The location of the areas measured in this work is shown in Fig. 9A. Given the orientation, facing an area to the north of the northernmost sunrise (summer solstice), Area 1, with the circular and reticulated motifs, would never be directly illuminated by sunlight. However, in Area 2, the sunrise could be seen directly from the entrance from nearly the autumn equinox to the spring equinox.

It is interesting to note that the nearly flat area next to the entrance of Area 1 where the CR3 engravings are located (Fig. 9C), would be directly illuminated during a period nearly coincidental with the winter months (from the autumn equinox to the spring equinox, nearly half a year) at midday. Finally, Area 2 could also be illuminated at astronomical events in this same period of time, and particularly at the winter solstice. The entrances to the shelter show somewhat ambiguous orientations, which is unsurprising, given that these are most probably natural. There is an entrance aligned north of the sunrise arch and another towards the southern part of this arch.

4. DISCUSSION AND CONCLUDING REMARKS  ⌅

The empirical evidence gathered for this study greatly expands previously published descriptions of the rock art present at El Riscal. The new renderings of the motifs and the more precise contextualisation of the panels across the topography of the shelter point to a complex rock art station, with ‘indoor’ and ‘outdoor’ engraved panels. Two kinds of engravings were identified: U-section circular motifs, and V-section linear grid designs. An important observation concerns the evidence of overlapping and over-cutting of the engraved motifs in some of the panels, which points to an extended use of the shelter. Two major types of motifs were found, which can be tentatively grouped in two differentiated ‘phases’ or ‘graphic horizons’ (although the chronological implications of these ‘phases’ are far from clear). Horizon 1 is characterised by the presence of circular figures, sometimes with concentric circles (CR1, CR2, CR5, CR6a, and CR7). Conversely, Horizon 2 is predominantly composed of intricate grid designs (CR3, CR4 and CR6b). It is noticeable that the two ‘phases’ are not mixed and do not occupy the same panels. The formal differences between the motifs of these panels could also be attributable to functional or symbolic variations, and not chronological.

Some of these engravings, in particular CR2 and CR4 panels, show a peculiar reddish colour. However, subsequent analysis has failed to detect any traces of paint. The red colouration is hypothesised to result from thermal transformation of some of the rock minerals, possibly induced by recent wildfires.

High-resolution archaeological survey of the shelter and its immediate surroundings provided some surface findings potentially compatible with activity between the Neolithic and the Iron Age. Particularly, the non-siliceous stone utensil and the stone hammer point to a chronology between the Neolithic and the Copper Age, although later chronologies cannot be ruled out. Only future numerical dating of samples obtained through excavation will allow a more precise chronology of the site.

El Riscal currently stands as the only rock art location published for the province of Seville. In Constantina (Seville), some 120 km to the east, a geological site with marine fossils (jellyfish dating to the Cambrian period) called Piedra Escrita (’Written Stone’) was wrongly interpreted as a rock art station until recently (Mayoral et al., 2004Mayoral, E., Liñán, E., Gámez Vintaned, J. A., Muñiz-Guinea, F. and Gozalo, R. (2004). “Stranded jellyfish in the lowermost Cambrian (Cordubian) of Spain”. Revista Española de Paleontología, 19 (2), pp. 191-198. DOI: https://doi.org/10.7203/sjp.19.2.20531.Mayoral, E., Liñán, E., Gámez Vintaned, J. A., Muñiz-Guinea, F. and Gozalo, R. (2004). “Stranded jellyfish in the lowermost Cambrian (Cordubian) of Spain”. Revista Española de Paleontología, 19 (2), pp. 191-198. DOI: https://doi.org/10.7203/sjp.19.2.20531.). But in the province of Huelva, not far from El Riscal, there are other rock art sites with engraved motifs. These include Los Aulagares (Del Amo, 1974Del Amo, M. (1974). “Los grabados rupestres de Los Aulagares, Zalamea la Real (Huelva)”. In: Miscelánea Arqueológica. XXV Aniversario de los Cursos Internacionales de Prehistoria y Arqueología en Ampurias (1947-71). Barcelona: Diputación de Barcelona, pp. 47-51.Del Amo, M. (1974). “Los grabados rupestres de Los Aulagares, Zalamea la Real (Huelva)”. In: Miscelánea Arqueológica. XXV Aniversario de los Cursos Internacionales de Prehistoria y Arqueología en Ampurias (1947-71). Barcelona: Diputación de Barcelona, pp. 47-51., with updated photographic documentation in Escacena, 2018Escacena Carrasco, J. L. (2018). “Ad petendam pluviam. El petroglifo de Los Aulagares como respuesta religiosa al evento climático 4.2 ka cal. BP”. Ilu. Revista de las Religiones, 23, pp. 81-110. DOI: https://doi.org/10.5209/ILUR.61022.Escacena Carrasco, J. L. (2018). “Ad petendam pluviam. El petroglifo de Los Aulagares como respuesta religiosa al evento climático 4.2 ka cal. BP”. Ilu. Revista de las Religiones, 23, pp. 81-110. DOI: https://doi.org/10.5209/ILUR.61022.), in the municipality of Zalamea la Real, some 20 km as the crow flies from El Madroño; Las Tierras (Belén Deamos, 1974Belén Deamos, M. (1974). “El petroglifo de ‘Las Tierras’ (Villanueva de los Castillejos, Huelva)”. Trabajos de Prehistoria, 31, pp. 337-348.Belén Deamos, M. (1974). “El petroglifo de ‘Las Tierras’ (Villanueva de los Castillejos, Huelva)”. Trabajos de Prehistoria, 31, pp. 337-348.), in the municipality of Villanueva de los Castillejos, and Los Azulejos (Pérez Macías, 1988Pérez Macías, J. A. (1988). “Los esquematismos de Los Azulejos, Santa Ana la Real. Nuevos grabados rupestres en Huelva”. In: Desde la Historia hacia el futuro: Actas del I Congreso Nacional Cuenca Minera de Riotinto. Riotinto 28, 29 y 30 de octubre de 1988, pp. 231-241. Riotinto (Huelva).Pérez Macías, J. A. (1988). “Los esquematismos de Los Azulejos, Santa Ana la Real. Nuevos grabados rupestres en Huelva”. In: Desde la Historia hacia el futuro: Actas del I Congreso Nacional Cuenca Minera de Riotinto. Riotinto 28, 29 y 30 de octubre de 1988, pp. 231-241. Riotinto (Huelva).), in the municipality of Santa Ana la Real. The graphic renderings available for these rock art sites follow publication standards of the 1970s, wherein the 2D tracing presents the existing engravings without any consideration of the supporting rock characteristics or shapes. They are mostly based on direct, naked-eye, hand-made tracings, often without the use of a minimum reference scale.

Formally, the engravings at El Riscal are completely different from those at Los Azulejos (Fig. 10C) which are more closely related to the repertoire of the Spanish painted schematic rock art. The art present at Horizon 1 at El Riscal holds a considerable formal similarity to that found at Los Aulagares (Fig. 10A), or even Las Tierras (Fig. 10B), in which circular shapes are clearly predominant. In particular, panel CR1 (Fig. 7A), including the circular motifs arranged vertically, displays a clear similarity to the motifs engraved at Los Aulagares. Interestingly, at least two circular shapes are shown in the tracing of Los Azulejos provided by Pérez Macías (1988Pérez Macías, J. A. (1988). “Los esquematismos de Los Azulejos, Santa Ana la Real. Nuevos grabados rupestres en Huelva”. In: Desde la Historia hacia el futuro: Actas del I Congreso Nacional Cuenca Minera de Riotinto. Riotinto 28, 29 y 30 de octubre de 1988, pp. 231-241. Riotinto (Huelva).Pérez Macías, J. A. (1988). “Los esquematismos de Los Azulejos, Santa Ana la Real. Nuevos grabados rupestres en Huelva”. In: Desde la Historia hacia el futuro: Actas del I Congreso Nacional Cuenca Minera de Riotinto. Riotinto 28, 29 y 30 de octubre de 1988, pp. 231-241. Riotinto (Huelva).) (Fig. 10C).

Given the lack of precise dating and the dearth of background information on prehistoric rock art for the western Andalusian provinces of Seville and Huelva, it is difficult to contextualise the style recorded at El Riscal within the wider Iberian framework. In general, painted rock art of the schematic style is quite abundant across central and southern Spain (Acosta Martínez, 1968Acosta Martínez, P. (1968). La Pintura Rupestre Esquemática. Salamanca: Universidad de Salamanca.Acosta Martínez, P. (1968). La Pintura Rupestre Esquemática. Salamanca: Universidad de Salamanca.; Martínez García, 2022Martínez García, J. (2022). “La pintura rupestre esquemática en Andalucía. Un siglo después de las primeras recopilaciones”. In: Gordón Baeza, J. J., Arias Sánchez, I. and Burgos Ávila, I. (Eds.). Actas del I Encuentro Nacional de Arte Rupestre. Investigación, Conservación, Gestión y Difusión, pp. 105-118. Madrid: Ministerio de Cultura y Deporte.Martínez García, J. (2022). “La pintura rupestre esquemática en Andalucía. Un siglo después de las primeras recopilaciones”. In: Gordón Baeza, J. J., Arias Sánchez, I. and Burgos Ávila, I. (Eds.). Actas del I Encuentro Nacional de Arte Rupestre. Investigación, Conservación, Gestión y Difusión, pp. 105-118. Madrid: Ministerio de Cultura y Deporte.). To the east of El Riscal, schematic rock art abounds in the provinces of Málaga (Maura Mijares, 2011Maura Mijares, R. (2011). Arte Prehistórico en las Tierras de Antequera. Sevilla: Junta de Andalucía.Maura Mijares, R. (2011). Arte Prehistórico en las Tierras de Antequera. Sevilla: Junta de Andalucía.) and Córdoba (Bernier Luque, 1969Bernier Luque, J. (1969). “Nuevas pinturas esquemáticas en la provincia de Córdoba”. Zephyrus, 19-20, pp. 143-164.Bernier Luque, J. (1969). “Nuevas pinturas esquemáticas en la provincia de Córdoba”. Zephyrus, 19-20, pp. 143-164.); to the north, in Badajoz (León and García Verdugo, 1984León, M. and García Verdugo, R. (1984). Pintura Rupestre Esquemática en Mérida. Sierra de Arroyo de San Serván. Badajoz: Caja de Ahorros de Badajoz.León, M. and García Verdugo, R. (1984). Pintura Rupestre Esquemática en Mérida. Sierra de Arroyo de San Serván. Badajoz: Caja de Ahorros de Badajoz.; Domínguez García and Aldecoa Quintana, 2007Domínguez García, A. and Aldecoa Quintana, M. A. (2007). Corpus de Arte Rupestre en Extremadura, Vol II. Arte Rupestre en la Zepa de la Serena: Puebla de Alcocer, Esparragosa de Lares y Campanario. Mérida: Junta de Extremadura.Domínguez García, A. and Aldecoa Quintana, M. A. (2007). Corpus de Arte Rupestre en Extremadura, Vol II. Arte Rupestre en la Zepa de la Serena: Puebla de Alcocer, Esparragosa de Lares y Campanario. Mérida: Junta de Extremadura.); and to the south-east, in Cádiz (Breuil and Burkitt, 1929Breuil, H. and Burkitt, M. (1929). Rock Painting of Southern Andalusia. A Description of a Neolithic and Copper Age Art Group. Oxford: Clarendon Press.Breuil, H. and Burkitt, M. (1929). Rock Painting of Southern Andalusia. A Description of a Neolithic and Copper Age Art Group. Oxford: Clarendon Press.; Topper and Topper, 1988Topper, U. and Topper, U. (1988). Arte Rupestre en la Provincia de Cádiz. Cádiz: Diputación Provincial de Cádiz.Topper, U. and Topper, U. (1988). Arte Rupestre en la Provincia de Cádiz. Cádiz: Diputación Provincial de Cádiz.; Carreras Egaña and Caballero García, 2006Carreras Egaña, A. M. and Caballero García, M. (2006). “Las pinturas rupestres esquemáticas de las sierras gaditanas: estado de la cuestión”. In: Simbolismo, Arte e Espaços Sagrados na Pré-Historia da Peninsula Iberica. Actas do IV Congresso de Arqueologia Peninsular (Faro, 14 a 19 Setembro 2004), pp. 193-204. Faro: Universidade do Algarve.Carreras Egaña, A. M. and Caballero García, M. (2006). “Las pinturas rupestres esquemáticas de las sierras gaditanas: estado de la cuestión”. In: Simbolismo, Arte e Espaços Sagrados na Pré-Historia da Peninsula Iberica. Actas do IV Congresso de Arqueologia Peninsular (Faro, 14 a 19 Setembro 2004), pp. 193-204. Faro: Universidade do Algarve.). And yet, save for Los Azulejos, this style is conspicuous by its absence in Huelva and Seville (and, further to the west, in Portugal). The El Riscal motifs, like those at Los Aulagares, are formally more akin to the engraved motifs, usually described as petroglyphs, found in north-west Iberia (Peña Santos, 2001Peña Santos, A. (2001). Petroglifos de Galicia. La Coruña: Vía Láctea.Peña Santos, A. (2001). Petroglifos de Galicia. La Coruña: Vía Láctea.; Bettencourt et al., 2017Bettencourt, A. M. S., Santos Estevez, M., Sampaio, H. and Cardoso, D. (Eds.) (2017). Recorded Places, Experienced Places. The Holocene Rock Art of the Iberian Atlantic North-West. British Archaeological Reports International Series 2878. Oxford: Archaeopress.Bettencourt, A. M. S., Santos Estevez, M., Sampaio, H. and Cardoso, D. (Eds.) (2017). Recorded Places, Experienced Places. The Holocene Rock Art of the Iberian Atlantic North-West. British Archaeological Reports International Series 2878. Oxford: Archaeopress.) or the British Isles (Bradley, 2023Bradley, R. (2023). “Long distance connections within Britain and Ireland: the evidence of insular rock art”. Proceedings of the Prehistoric Society, 89, pp. 249-271. DOI: https://doi.org/10.1017/ppr.2023.9.Bradley, R. (2023). “Long distance connections within Britain and Ireland: the evidence of insular rock art”. Proceedings of the Prehistoric Society, 89, pp. 249-271. DOI: https://doi.org/10.1017/ppr.2023.9.), where circles in isolation or forming complex arrangements are common.

Thus, a non-comprehensive list of rock art sites with motifs similar to those found at El Riscal should include Outeiro dos Lameiros (Baiona), Pedra da Serpe (Valga), A Pedreira 2 (Caldas de Reis), Monte Xiabre 2, and Sobreiras 4 and 5 (Vilagarcía de Arousa) (Cabrejas Domínguez et al., 2008Cabrejas Domínguez, E., Seoane Veiga, Y. and Varela Pousa, R. (2008). “A descuberta dos petróglifos da bacía do río Salgueiro no monte Xiabre. Documentación e rexistro”. El Museo de Pontevedra, 62, pp. 11-28.Cabrejas Domínguez, E., Seoane Veiga, Y. and Varela Pousa, R. (2008). “A descuberta dos petróglifos da bacía do río Salgueiro no monte Xiabre. Documentación e rexistro”. El Museo de Pontevedra, 62, pp. 11-28.), or Aldea Deiro (Vila Nova de Arousa) in Galicia; and others such as Monte das Fortes, and O Escarabelhão (Valença do Minho) (Bacelar Alves and Reis, 2017Bacelar Alves, L. and Reis, M. (2017). “As gravuras rupestres do Monte Faro (Valença, Viana do Castelo) - Um exemplo maior da Arte Atlântica peninsular”. Portvgalia, Nova Série, 38, pp. 49-86. DOI: https://doi.org/10.21747/09714290/port38a2.Bacelar Alves, L. and Reis, M. (2017). “As gravuras rupestres do Monte Faro (Valença, Viana do Castelo) - Um exemplo maior da Arte Atlântica peninsular”. Portvgalia, Nova Série, 38, pp. 49-86. DOI: https://doi.org/10.21747/09714290/port38a2.), Moulães, Pereiras, and Monte da Porqueira 2-3 (Monção), Penedo dos Sinais (Valdez and Oliveira, 2005-2006Valdez, J. and Oliveira, L. (2005-2006). “A arte rupestre da Citânia de Briteiros - o Penedo dos Sinais, um caso atlántico”. Revista de Guimarães, 115-116, pp. 51-92.Valdez, J. and Oliveira, L. (2005-2006). “A arte rupestre da Citânia de Briteiros - o Penedo dos Sinais, um caso atlántico”. Revista de Guimarães, 115-116, pp. 51-92.), Quinta do Paço (Cardoso, 2013Cardoso, D. (2013). “Gravuras rupestres da Quinta do Paço, S. Salvador de Briteiros, Guimarães”. In: Bethencourt, A. M. S. (Ed.). A Pré-História do Noroeste Português. Arkeos 36, pp. 222-228.Cardoso, D. (2013). “Gravuras rupestres da Quinta do Paço, S. Salvador de Briteiros, Guimarães”. In: Bethencourt, A. M. S. (Ed.). A Pré-História do Noroeste Português. Arkeos 36, pp. 222-228.), and Citânia dos Briteiros (Guimarães), or Laje dos Sinais (Carvalhas-Barcelos) (Cardozo, 1951Cardozo, M. (1951). “Monumentos Arqueológicos da Sociedade Martins Sarmento”. Revista de Guimarães, 61, pp. 5-28.Cardozo, M. (1951). “Monumentos Arqueológicos da Sociedade Martins Sarmento”. Revista de Guimarães, 61, pp. 5-28.) and Pedra Escrita (Serrazes) (Sobrino Lorenzo-Rua, 1957Sobrino Lorenzo-Rua, R. (1957). “Bosquejo para un estudio de los petroglifos portugueses”. Caesaraugusta, 7-8, pp. 49-65.Sobrino Lorenzo-Rua, R. (1957). “Bosquejo para un estudio de los petroglifos portugueses”. Caesaraugusta, 7-8, pp. 49-65.) in northern Portugal. These and more examples are published in the website “Megaliticia”³3 https://megaliticia.blogspot.com/.. The recent discovery of engraved stelae of the ‘warrior’ type in Huelva (Rivera Jiménez et al., 2021Rivera Jiménez, T., García Sanjuán, L., Díaz-Guardamino, M., Donaire Romero, T., Morales González, J. A., Lozano Rodríguez, J. A.,… and Aguilera Collado, E. (2021). “The Cañaveral de León stela (Huelva, Spain). A monumental sculpture in a landscape of settlements and pathways”. Journal of Archaeological Science: Reports, 40 (A), 103251. DOI: https://doi.org/10.1016/j.jasrep.2021.103251.Rivera Jiménez, T., García Sanjuán, L., Díaz-Guardamino, M., Donaire Romero, T., Morales González, J. A., Lozano Rodríguez, J. A.,… and Aguilera Collado, E. (2021). “The Cañaveral de León stela (Huelva, Spain). A monumental sculpture in a landscape of settlements and pathways”. Journal of Archaeological Science: Reports, 40 (A), 103251. DOI: https://doi.org/10.1016/j.jasrep.2021.103251.; García Sanjuán et al., 2025García Sanjuán, L., Rivera-Jiménez, T., Díaz-Guardamino, M., Wheatley, D., Lozano Rodríguez, J. A., Donaire Romero, T.,… and Bailiff, I. (2025). “Shedding new light on the context and temporality of Iberian warrior stelae: The Cañaveral de León 2 Stela and Las Capellanías burial complex (Huelva, SW Spain)”. PLoS ONE, 20 (4), e0321080. DOI: https://doi.org/10.1371/journal.pone.0321080.García Sanjuán, L., Rivera-Jiménez, T., Díaz-Guardamino, M., Wheatley, D., Lozano Rodríguez, J. A., Donaire Romero, T.,… and Bailiff, I. (2025). “Shedding new light on the context and temporality of Iberian warrior stelae: The Cañaveral de León 2 Stela and Las Capellanías burial complex (Huelva, SW Spain)”. PLoS ONE, 20 (4), e0321080. DOI: https://doi.org/10.1371/journal.pone.0321080.), firmly places this territory within the general background of the late prehistoric stelae known along the basins of the main Iberian rivers draining into the Atlantic (the Guadalquivir, Guadiana and Tagus). Therefore, it is unsurprising that the best analogues for the motifs found at El Riscal are not found in the Levantine or schematic styles, which are deeply-rooted in central, southern and eastern Spain, but rather from the western tradition visible in northern Portugal and Galicia.

Atlantic and schematic art represent two distinctive rock art traditions within Iberia, and (variously arranged) circles are a pervasive image, strongly characteristic of the former (Bacelar Alves, 2012Bacelar Alves, L. (2012). “The circle, the cross and the limits of abstraction and figuration in north-western Iberian rock art”. In: Cochrane, A. and Jones, A. M. (Eds.). Visualising the Neolithic: Abstraction, Figuration, Performance, Representation. Neolithic Studies Group Seminar Papers 13, Oxford: Oxbow, pp. 198-214. DOI: https://doi.org/10.2307/j.ctvh1dwd6.17.Bacelar Alves, L. (2012). “The circle, the cross and the limits of abstraction and figuration in north-western Iberian rock art”. In: Cochrane, A. and Jones, A. M. (Eds.). Visualising the Neolithic: Abstraction, Figuration, Performance, Representation. Neolithic Studies Group Seminar Papers 13, Oxford: Oxbow, pp. 198-214. DOI: https://doi.org/10.2307/j.ctvh1dwd6.17., p. 198). In this sense, it is worth noting that circles (often concentric) interpreted as ‘shields’ are one of the most recurrent motifs in late prehistoric ‘warrior’ stelae, a form of rock art of strong Atlantic distribution (Hernando Grande, 1976Hernando Grande, A. (1976). “Representaciones del escudo en la Península Ibérica: escudos en estelas”. Cuadernos de Prehistoria y Arqueología de la Universidad Autónoma de Madrid, 3, pp. 127-135.Hernando Grande, A. (1976). “Representaciones del escudo en la Península Ibérica: escudos en estelas”. Cuadernos de Prehistoria y Arqueología de la Universidad Autónoma de Madrid, 3, pp. 127-135.; Díaz-Guardamino, 2010Díaz-Guardamino, M. (2010). Las Estelas Decoradas de la Prehistoria de la Península Ibérica. PhD Thesis dissertation. Madrid: Universidad Complutense de Madrid. Available at: https://hdl.handle.net/20.500.14352/47389.Díaz-Guardamino, M. (2010). Las Estelas Decoradas de la Prehistoria de la Península Ibérica. PhD Thesis dissertation. Madrid: Universidad Complutense de Madrid. Available at: https://hdl.handle.net/20.500.14352/47389.). They are also found in the ‘megalithic art’ present in the Soto dolmen (Trigueros, Huelva), located 60 km to the south-west of El Riscal (Obermaier, 1924Obermaier, H. (1924). El Dolmen de Soto (Trigueros, Huelva). Madrid: Hauser y Menet.Obermaier, H. (1924). El Dolmen de Soto (Trigueros, Huelva). Madrid: Hauser y Menet.). The reticulate motifs are also present in a variate sample of Atlantic rock art sites, as those already quoted of Monte dos Fortes, O Escarabelhão, Pereiras, and others.

Certainly, the interpretation of rock art encompasses a multitude of factors beyond the formal variability of the motifs. Landscape settings, context and association to other archaeological remains carry as much interpretative weight, or more, than the motifs themselves. In the case of Huelva, however, the presence of schematic (Los Azulejos) and Atlantic (El Riscal) rock art within the same territory points to the kind of ‘border’ or ‘fringe’ interaction between styles already noted for Galicia (Bradley and Fábregas Valcarce, 1998Bradley, R. and Fábregas Valcarce, R. (1998). “Crossing the border: contrasting styles of rock art in the prehistory of North-West Iberia”. Oxford Journal of Archaeology, 17, pp. 287-308. DOI: https://doi.org/10.1111/1468-0092.00064.Bradley, R. and Fábregas Valcarce, R. (1998). “Crossing the border: contrasting styles of rock art in the prehistory of North-West Iberia”. Oxford Journal of Archaeology, 17, pp. 287-308. DOI: https://doi.org/10.1111/1468-0092.00064., 1999Bradley, R. and Fábregas Valcarce, R. (1999). “La ‘ley de la frontera’: grupos rupestres galaico y esquemático y Prehistoria del Noroeste de la Península Ibérica”. Trabajos de Prehistoria, 56 (1), pp. 103-114. DOI: https://doi.org/10.3989/tp.1999.v56.i1.292.Bradley, R. and Fábregas Valcarce, R. (1999). “La ‘ley de la frontera’: grupos rupestres galaico y esquemático y Prehistoria del Noroeste de la Península Ibérica”. Trabajos de Prehistoria, 56 (1), pp. 103-114. DOI: https://doi.org/10.3989/tp.1999.v56.i1.292.) and, with a different definition, in other areas (Bueno Ramírez et al., 2009Bueno Ramírez, P., De Balbín Behrmann, R. and Barroso Bermejo, R. (2009) “Constructores de Megalitos y Marcadores Gráficos. Diacronías y Sincronías en el Atlántico Ibérico”. In: De Balbín Behrmann, R., Bueno Ramírez, P., González Antón, R. and del Arco Aguilar, C. (Eds.). Grabados rupestres de la fachada atlántica europea y africana. Oxford: Archaeopress. BAR International Series 2043, pp. 149-172.Bueno Ramírez, P., De Balbín Behrmann, R. and Barroso Bermejo, R. (2009) “Constructores de Megalitos y Marcadores Gráficos. Diacronías y Sincronías en el Atlántico Ibérico”. In: De Balbín Behrmann, R., Bueno Ramírez, P., González Antón, R. and del Arco Aguilar, C. (Eds.). Grabados rupestres de la fachada atlántica europea y africana. Oxford: Archaeopress. BAR International Series 2043, pp. 149-172.; Collado Giraldo and García Arranz, 2013Collado Giraldo, H. and García Arranz, J. J. (2013). “Reflexiones sobre la fase inicial del arte rupestre esquemático en Extremadura a raíz de las recientes investigaciones”. In: Martínez García, J. and Hernández Pérez, M. S. (Eds.). Actas del II Congreso de Arte Rupestre Esquemático en la Península Ibérica: Comarca de Los Vélez, 5-8 de mayo 2010. Vélez-Blanco: Ayuntamiento de Vélez-Blanco, pp. 287-299.Collado Giraldo, H. and García Arranz, J. J. (2013). “Reflexiones sobre la fase inicial del arte rupestre esquemático en Extremadura a raíz de las recientes investigaciones”. In: Martínez García, J. and Hernández Pérez, M. S. (Eds.). Actas del II Congreso de Arte Rupestre Esquemático en la Península Ibérica: Comarca de Los Vélez, 5-8 de mayo 2010. Vélez-Blanco: Ayuntamiento de Vélez-Blanco, pp. 287-299.; Santos-Estévez et al., 2020Santos-Estévez, M., Tejerizo García, C. and Alonso Toucido, F. (2020). “El abrigo con pintura esquemática de Pala de Cabras (Ourense). Encuentros y desencuentros entre dos tradiciones”. Complutum, 31 (1), pp. 7-24. DOI: https://doi.org/10.5209/cmpl.71647.Santos-Estévez, M., Tejerizo García, C. and Alonso Toucido, F. (2020). “El abrigo con pintura esquemática de Pala de Cabras (Ourense). Encuentros y desencuentros entre dos tradiciones”. Complutum, 31 (1), pp. 7-24. DOI: https://doi.org/10.5209/cmpl.71647.). Needless to say, we do not conceive the term ‘border’ in a literal sense (as in the political border of a modern state, for example) but rather as a zone of transition between regions where different styles prevail. This is consistent with the very geographical position of sites like El Riscal or Los Azulejos, which are within the Atlantic hydrological domain, but relatively adjacent, and well connected, with the Mediterranean.

Though it is tempting to try to ‘identify’, or connect, the circles as specific forms (whether they be landforms, shields or other artefacts or more abstract ideas), and there is no shortage of such interpretations in the literature–Iberian late prehistoric stelae are a supreme example of this–, no attempt will be made here to it. While greatly enhanced, the new ‘image’ of El Riscal is still partly blurred, as chronology and context are yet poorly understood. Regardless of the specific meanings, which of course would have changed over time, the site appears to have remained a local focus of activity for an extended period of time. As noted for north-west Iberia, in the Bronze Age and Iron Age, new carvings were certainly created or added onto previously existing motifs, a process of renewal or re-appropriation of sites and pasts (Bacelar Alves, 2012Bacelar Alves, L. (2012). “The circle, the cross and the limits of abstraction and figuration in north-western Iberian rock art”. In: Cochrane, A. and Jones, A. M. (Eds.). Visualising the Neolithic: Abstraction, Figuration, Performance, Representation. Neolithic Studies Group Seminar Papers 13, Oxford: Oxbow, pp. 198-214. DOI: https://doi.org/10.2307/j.ctvh1dwd6.17.Bacelar Alves, L. (2012). “The circle, the cross and the limits of abstraction and figuration in north-western Iberian rock art”. In: Cochrane, A. and Jones, A. M. (Eds.). Visualising the Neolithic: Abstraction, Figuration, Performance, Representation. Neolithic Studies Group Seminar Papers 13, Oxford: Oxbow, pp. 198-214. DOI: https://doi.org/10.2307/j.ctvh1dwd6.17., p. 208).

This phenomenon could well have been connected with the periodical frequentation of the site at specific times of the year. The archaeoastronomical analysis shows that some of the engravings may have been illuminated at particularly relevant moments during the year. In this regard, the CR3 engravings appear as particularly interesting, and the location seems to have been chosen so that they could be illuminated during a period of time each day in the course of the winter months. In Iberia, a similar phenomenon has been noted at A Ferradura, in Galicia, north-west Spain (García Quintela and Santos Estévez, 2008García Quintela, M. V. and Santos Estévez, M. (2008). Santuarios de la Galicia Céltica. Arqueología del Paisaje y Religiones Comparadas en la Edad del Hierro. Madrid: Abada Editores.García Quintela, M. V. and Santos Estévez, M. (2008). Santuarios de la Galicia Céltica. Arqueología del Paisaje y Religiones Comparadas en la Edad del Hierro. Madrid: Abada Editores.), as well as in other places, like inside the chamber of some megalithic tombs in Ireland (see Prendergast et al., 2017Prendergast, F., O’Sullivan, M., Williams, K. and Cooney, G. (2017). “Facing the Sun”. Archaeology Ireland, 31 (4), pp. 10-17. DOI: https://www.jstor.org/stable/90019263.Prendergast, F., O’Sullivan, M., Williams, K. and Cooney, G. (2017). “Facing the Sun”. Archaeology Ireland, 31 (4), pp. 10-17. DOI: https://www.jstor.org/stable/90019263. for a recent review). Elsewhere, it is worth mentioning Fajada Butte (New Mexico, USA) (Sofaer et al., 1979Sofaer, A., Zinser, V. and Sinclair, R. M. (1979). “A unique solar marking construct”. Science, 206, pp. 283-291. DOI: https://www.jstor.org/stable/pdf/1749388.pdf.Sofaer, A., Zinser, V. and Sinclair, R. M. (1979). “A unique solar marking construct”. Science, 206, pp. 283-291. DOI: https://www.jstor.org/stable/pdf/1749388.pdf.; Williamson, 2015Williamson, R. (2015). “Sun-Dagger sites”. In: Ruggles, C. L. N. (Ed.). Handbook of Archaeoastronomy and Ethnoastronomy, pp. 621-628. New York: Springer.Williamson, R. (2015). “Sun-Dagger sites”. In: Ruggles, C. L. N. (Ed.). Handbook of Archaeoastronomy and Ethnoastronomy, pp. 621-628. New York: Springer.). This suggests that there might have been ritual areas connected to specific periods of interest for the people who made the engravings. It would also be interesting to verify whether Area 2 would be directly lit a few hours after the winter solstice sunrise.

Fresh, multi-disciplinary research undertaken between 2022 and 2024 at El Riscal (Seville, south-west Spain) has greatly expanded the understanding of this remarkable site, further emphasizing its importance to comprehend the geographical distribution of Iberian rock art traditions and styles, and providing suggestive evidence that underlines its pervasive significance through time. The results presented demonstrate the importance of re-studying specific rock art sites in the light of novel methods and techniques. Furthermore, they underscore the need for additional research to address new, more precise questions.

SUPPLEMENTARY FILES  ⌅

The following supplementary material is available on this journal’s website:

- Annex 1. Figs. S1-S11.

- Annex 2. CR2 & CR3 interactive 3D record.

- Annex 3. CR4 interactive 3D record.

ACKNOWLEDGEMENTS  ⌅

We would like to thank the two anonymous reviewers for their contribution to improving the paper. Aquilino Delgado (Mining Museum of Riotinto) is acknowledged for the facilities documenting CR1 panel. A. F. P. acknowledges Consejería de Economía, Conocimiento y Empleo of the Government of the Canary Islands, and the European Social Fund, for funding by means of a Catalina Ruiz grant. Project IN607D 2023/13, Xunta de Galicia, is also acknowledged. We are grateful to Judit Praena García and Manuel Tristán Martín Ruiz for their invaluable help in the archaeological prospection of the shelter. Junta de Andalucía, contract 2021 0000667050 is acknowledged for funding and permissions. We also wish to acknowledge the support of the CSIC Interdisciplinary Thematic Platform Open Heritage: Research and Society (PTI-PAIS) and CSIC’s ArchaeologyHub.

DECLARATION OF COMPETING INTERESTS  ⌅

The authors declare that they have not known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

FUNDING SOURCES  ⌅

The archaeological prospections were funded by the Junta de Andalucía (contract 2021 0000667050).

AUTHORSHIP CONTRIBUTION STATEMENT  ⌅

Miguel Ángel Rogerio-Candelera: conceptualisation, investigation, methodology, writing – original draft, writing – review & editing.

Alba Fuentes Porto: investigation, methodology, writing-original draft, writing – review & editing.

Timoteo Rivera Jiménez: funding acquisition, investigation, methodology, writing – original draft, writing – review & editing.

Jordi Ibáñez Insa: investigation, methodology, writing-original draft, writing – review & editing.

José Antonio Lozano Rodríguez: investigation, methodology, writing – original draft, writing – review & editing.

César González García: investigation, methodology, writing – original draft, writing – review & editing.

Raquel Montero Artús: investigation, writing – review & editing.

Leonardo García Sanjuán: conceptualisation, investigation, methodology, writing – original draft, writing – review & editing.

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¹ Ecologistas en Acción (2019). Llevan tres años intentando quemar El Madroño y al final lo han conseguido [on line: https://www.ecologistasenaccion.org/125739/llevan-tres-anos-intentando-quemar-el-madrono-y-al-final-lo-han-conseguido/].

² This is our translation.

³ https://megaliticia.blogspot.com/.