{"id":21954,"date":"2025-10-05T11:13:40","date_gmt":"2025-10-05T10:13:40","guid":{"rendered":"https:\/\/gem.pt\/1\/?page_id=21954"},"modified":"2025-10-22T23:44:06","modified_gmt":"2025-10-22T22:44:06","slug":"algar-da-cancela-ii","status":"publish","type":"page","link":"https:\/\/gem.pt\/1\/en\/publicacoes\/carso-e-endocarso\/algar-da-cancela-ii\/","title":{"rendered":"Algar da Cancela II - Some Notes"},"content":{"rendered":"<figure>\n\t\t\t\t\t\t\t\t\t\t<img fetchpriority=\"high\" width=\"1500\" height=\"500\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Algar-da-Cancela-II_pan.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Algar-da-Cancela-II_pan.jpg 1500w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Algar-da-Cancela-II_pan-18x6.jpg 18w\" sizes=\"(max-width: 1500px) 100vw, 1500px\" \/><figcaption>Algar da Cancela II - Some Notes<\/figcaption><\/figure>\n<p>\t\tOctober 5, 2025<\/p>\n<p>Rodrigues, Afonso 1\u00a0- <a href=\"#introducao\">Introduction and Location<\/a>, <a href=\"#resenha\">Historical Review<\/a>, <a href=\"#descricao\">Description<\/a> e <a href=\"#topo\">Topography<\/a><\/p>\n<p>Rodrigues, Paulo\u00a0<sup>1,2,3 <\/sup> - <a href=\"#enquadramentogeologico\">Geological Setting<\/a>, <a href=\"#controloestrutural\">Structural Control<\/a> e <a href=\"#genese\">Genesis and Evolution<\/a>\u00a0<\/p>\n<ol>\n<li style=\"letter-spacing: normal; margin: 10px; padding: 0px; font-family: Questrial; font-size: 13px; white-space: pre-line; line-height: 0.9;\">Grupo de Espeleologia e Montanhismo, Rua General Pereira de E\u00e7a, n\u00ba30, 2380-075 Alcanena<\/li>\n<li style=\"letter-spacing: normal; margin: 10px; padding: 0px; font-family: Questrial; font-size: 13px; white-space: pre-line; line-height: 0.9;\">N\u00facleo dos Amigos das Lapas Grutas e Algares\u00a0<\/li>\n<li style=\"letter-spacing: normal; margin: 10px; padding: 0px; font-family: Questrial; font-size: 13px; white-space: pre-line; line-height: 0.9;\">Comiss\u00e3o Cient\u00edfica da Federa\u00e7\u00e3o Portuguesa de Espeleologia,Estrada Calhariz de Benfica, 187, 1500-124 Lisboa\u00a0<\/li>\n<\/ol>\n<hr \/>\n<p>Introduction and Location<\/p>\n<p>The Algar da Cancela II cave is situated in the Maci\u00e7o Calc\u00e1rio Estremenho (MCE) (Estremenho Limestone Massif), central Portugal. It lies on the Cancela slope, a hillside of an elevation located near the southern limit of the MCE, between the Serra dos Candeeiros and the Polge da Mendiga, not far from the town of Xartinho.\nThe geographical coordinates (WGS84) of the cave entrance are: Latitude: 39.44497\u00ba, Longitude: \u22128.87281\u00ba, and approximate Z (elevation) of 297 metres.<\/p>\n<figure>\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_1a_Satelite_longe.jpg\" data-elementor-open-lightbox=\"yes\" data-elementor-lightbox-title=\"Figura 1 - Localiza\u00e7\u00e3o do Algar da Cancela II (imagem de sat\u00e9lite com planta em roxo).\" data-e-action-hash=\"#elementor-action%3Aaction%3Dlightbox%26settings%3DeyJpZCI6MjE5NTksInVybCI6Imh0dHBzOlwvXC9nZW0ucHRcL3dwLWNvbnRlbnRcL3VwbG9hZHNcLzIwMjVcLzEwXC9GaWd1cmFfMWFfU2F0ZWxpdGVfbG9uZ2UuanBnIn0%3D\"><br \/>\n\t\t\t\t\t\t\t<img width=\"850\" height=\"1300\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_1a_Satelite_longe.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_1a_Satelite_longe.jpg 850w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_1a_Satelite_longe-8x12.jpg 8w\" sizes=\"(max-width: 850px) 100vw, 850px\" \/>\t\t\t\t\t\t\t\t<\/a><figcaption>Figure 1 - Location of Algar da Cancela II (purple outline on satellite photo).<\/figcaption><\/figure>\n<figure>\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_2b_satelite_lperto.jpg\" data-elementor-open-lightbox=\"yes\" data-elementor-lightbox-title=\"Figura 1a - Amplia\u00e7\u00e3o da imagem de sat\u00e9lite com planta em roxo.\" data-e-action-hash=\"#elementor-action%3Aaction%3Dlightbox%26settings%3DeyJpZCI6MjE5NjEsInVybCI6Imh0dHBzOlwvXC9nZW0ucHRcL3dwLWNvbnRlbnRcL3VwbG9hZHNcLzIwMjVcLzEwXC9GaWd1cmFfMmJfc2F0ZWxpdGVfbHBlcnRvLmpwZyJ9\"><br \/>\n\t\t\t\t\t\t\t<img width=\"850\" height=\"1300\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_2b_satelite_lperto.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_2b_satelite_lperto.jpg 850w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_2b_satelite_lperto-8x12.jpg 8w\" sizes=\"(max-width: 850px) 100vw, 850px\" \/>\t\t\t\t\t\t\t\t<\/a><figcaption>Figure 1a - Zoom of satellite photo with purple outline.<\/figcaption><\/figure>\n<p>Historical Review<\/p>\n<p>It was possible to ascertain the existence of 2 historical work campaigns in this cave, although it seems highly likely that the cave had a lot of undocumented visitation and work.<\/p>\n<ul>\n<li>Ferreira (1962) apresenta numa separata do boletim da SPE (Sociedade Portuguesa de Espeleologia) uma nota sobre a gruta, com situa\u00e7\u00e3o geogr\u00e1fica, geologia local, espeleog\u00e9nese, espeleomorfologia e um perfil da parte inicial da gruta, incluindo o po\u00e7o de entrada. O acesso ao restante da cavidade \u00e9 marcado com um ponto de interroga\u00e7\u00e3o. Admite-se que posteriormente \u00e0 topografia tenha sido feita uma desobstru\u00e7\u00e3o nessa zona, dando acesso ao resto da cavidade. De salientar a qualidade do artigo. Como nota refira-se que a melhor descri\u00e7\u00e3o da entrada da gruta: \u201calgar-rampa\u201d encontra-se neste artigo.<\/li>\n<\/ul>\n<figure>\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_2_Topografia-do-Algar-da-Cancela_SPE.jpg\" data-elementor-open-lightbox=\"yes\" data-elementor-lightbox-title=\"Figura 2 - Topografia do Algar da Cancela II segundo Ferreira (1962).\" data-e-action-hash=\"#elementor-action%3Aaction%3Dlightbox%26settings%3DeyJpZCI6MjE5NjAsInVybCI6Imh0dHBzOlwvXC9nZW0ucHRcL3dwLWNvbnRlbnRcL3VwbG9hZHNcLzIwMjVcLzEwXC9GaWd1cmFfMl9Ub3BvZ3JhZmlhLWRvLUFsZ2FyLWRhLUNhbmNlbGFfU1BFLmpwZyJ9\"><br \/>\n\t\t\t\t\t\t\t<img loading=\"lazy\" width=\"990\" height=\"700\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_2_Topografia-do-Algar-da-Cancela_SPE.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_2_Topografia-do-Algar-da-Cancela_SPE.jpg 990w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_2_Topografia-do-Algar-da-Cancela_SPE-18x12.jpg 18w\" sizes=\"(max-width: 990px) 100vw, 990px\" \/>\t\t\t\t\t\t\t\t<\/a><figcaption>Figure 2 - Topography of Algar da Cancela II according to Ferreira (1962).<\/figcaption><\/figure>\n<ul>\n<li>The cave was visited by speleologists from GEM and AESDA (Association for Subterranean Studies and Environmental Defence) in 2017. Following this visit, a group of speleologists from various associations carried out laborious unblocking works and the topography of the cave (which can be seen in Figures 3 and 4). We thank Bruno Pais (AESDA) for providing the topography and helping with the historical review. This is the first known integral topography of the cave. The names of the field team and the topography authors can be consulted in Figures 3 and 4.<\/li>\n<\/ul>\n<figure>\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_3_Topografia_-Planta-Bruno-Pais.jpg\" data-elementor-open-lightbox=\"yes\" data-elementor-lightbox-title=\"Figura 3 - Planta do Algar da Cancela II (topografia cedida por Bruno Pais).\" data-e-action-hash=\"#elementor-action%3Aaction%3Dlightbox%26settings%3DeyJpZCI6MjE5NjIsInVybCI6Imh0dHBzOlwvXC9nZW0ucHRcL3dwLWNvbnRlbnRcL3VwbG9hZHNcLzIwMjVcLzEwXC9GaWd1cmFfM19Ub3BvZ3JhZmlhXy1QbGFudGEtQnJ1bm8tUGFpcy5qcGcifQ%3D%3D\"><br \/>\n\t\t\t\t\t\t\t<img loading=\"lazy\" width=\"655\" height=\"850\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_3_Topografia_-Planta-Bruno-Pais.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_3_Topografia_-Planta-Bruno-Pais.jpg 655w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_3_Topografia_-Planta-Bruno-Pais-9x12.jpg 9w\" sizes=\"(max-width: 655px) 100vw, 655px\" \/>\t\t\t\t\t\t\t\t<\/a><figcaption>Figure 3 - Plan view of Algar da Cancela II \u2013 Topography provided by Bruno Pais.<\/figcaption><\/figure>\n<figure>\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_4_Topografia_-Perfil-Bruno-Pais.jpg\" data-elementor-open-lightbox=\"yes\" data-elementor-lightbox-title=\"Figura 4 - Perfil do Algar da Cancela II (topografia cedida por Bruno Pais).\" data-e-action-hash=\"#elementor-action%3Aaction%3Dlightbox%26settings%3DeyJpZCI6MjE5NjMsInVybCI6Imh0dHBzOlwvXC9nZW0ucHRcL3dwLWNvbnRlbnRcL3VwbG9hZHNcLzIwMjVcLzEwXC9GaWd1cmFfNF9Ub3BvZ3JhZmlhXy1QZXJmaWwtQnJ1bm8tUGFpcy5qcGcifQ%3D%3D\"><br \/>\n\t\t\t\t\t\t\t<img loading=\"lazy\" width=\"800\" height=\"640\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_4_Topografia_-Perfil-Bruno-Pais.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_4_Topografia_-Perfil-Bruno-Pais.jpg 800w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_4_Topografia_-Perfil-Bruno-Pais-15x12.jpg 15w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/>\t\t\t\t\t\t\t\t<\/a><figcaption>Figure 4 - Extended Profile of Algar da Cancela II \u2013 Topography provided by Bruno Pais.<\/figcaption><\/figure>\n<p>Description<\/p>\n<p>Starting from the vertical and rounded entrance, which opens in a cornice (Ferreira, 1962), one descends a series of drops that lead to a chamber. This chamber has a block floor and a ceiling\/walls deeply marked by spongy dissolution (spongiform dissolution), with some associated speleothem deposits (concretion).\nThe series of shafts and drops has a vertical extent of approximately 20m. At the south end of the chamber, there is a small shaft filled with stones, corresponding to the deepest point of the cavity.\nThe cave continues north, ascending a stalagmitic flow in a heavily concrecionated  area. The route continues through a low and relatively inconspicuous passage, with the subsequent section being narrower and muddier. Several small chambers are passed, featuring ceiling pockets (ceiling cavities\/cupolas) that reveal old circulation under pressure. One also sees suspended calcite shelves formed when the conduits would have been silted up.<\/p>\n<figure>\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_5_Boca_-da-gruta.jpg\" data-elementor-open-lightbox=\"yes\" data-elementor-lightbox-title=\"Figura 5 - Boca da gruta (Foto: Afonso Rodrigues - GEM). De notar o aspeto arredondado da sec\u00e7\u00e3o da entrada.\" data-e-action-hash=\"#elementor-action%3Aaction%3Dlightbox%26settings%3DeyJpZCI6MjE5NjQsInVybCI6Imh0dHBzOlwvXC9nZW0ucHRcL3dwLWNvbnRlbnRcL3VwbG9hZHNcLzIwMjVcLzEwXC9GaWd1cmFfNV9Cb2NhXy1kYS1ncnV0YS5qcGcifQ%3D%3D\"><br \/>\n\t\t\t\t\t\t\t<img loading=\"lazy\" width=\"1000\" height=\"750\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_5_Boca_-da-gruta.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_5_Boca_-da-gruta.jpg 1000w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_5_Boca_-da-gruta-16x12.jpg 16w\" sizes=\"(max-width: 1000px) 100vw, 1000px\" \/>\t\t\t\t\t\t\t\t<\/a><figcaption>Figure 5 - Mouth of the cave (Photo: Afonso Rodrigues - GEM). Note the rounded appearance of the entrance section.<\/figcaption><\/figure>\n<p>There is a gallery that branches off again to the south, terminating very close to the end of another small meander, and the hypothesis is raised that there might have been a past connection. Decimetre-sized erosion scallops are visible in several of the passages.\nEventually, a near-vertical drop is reached, leading to a larger chamber where prominent ceiling channels can be seen.<\/p>\n<figure>\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_6_teto.jpg\" data-elementor-open-lightbox=\"yes\" data-elementor-lightbox-title=\"Figura 6 - Aspeto do teto da galeria (Foto: Afonso Rodrigues - GEM). Note-se o aspeto corro\u00eddo.\" data-e-action-hash=\"#elementor-action%3Aaction%3Dlightbox%26settings%3DeyJpZCI6MjE5NjUsInVybCI6Imh0dHBzOlwvXC9nZW0ucHRcL3dwLWNvbnRlbnRcL3VwbG9hZHNcLzIwMjVcLzEwXC9GaWd1cmFfNl90ZXRvLmpwZyJ9\"><br \/>\n\t\t\t\t\t\t\t<img loading=\"lazy\" width=\"1000\" height=\"750\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_6_teto.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_6_teto.jpg 1000w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_6_teto-16x12.jpg 16w\" sizes=\"(max-width: 1000px) 100vw, 1000px\" \/>\t\t\t\t\t\t\t\t<\/a><figcaption>Figure 6 - Aspect of the gallery ceiling (Photo: Afonso Rodrigues - GEM). Note the corroded appearance.<\/figcaption><\/figure>\n<figure>\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_7_descontinuidade.jpg\" data-elementor-open-lightbox=\"yes\" data-elementor-lightbox-title=\"Figura 7 - Descontinuidade vertical que controla a zona terminal da gruta (Foto: Afonso Rodrigues - GEM).\" data-e-action-hash=\"#elementor-action%3Aaction%3Dlightbox%26settings%3DeyJpZCI6MjE5NjYsInVybCI6Imh0dHBzOlwvXC9nZW0ucHRcL3dwLWNvbnRlbnRcL3VwbG9hZHNcLzIwMjVcLzEwXC9GaWd1cmFfN19kZXNjb250aW51aWRhZGUuanBnIn0%3D\"><br \/>\n\t\t\t\t\t\t\t<img loading=\"lazy\" width=\"750\" height=\"1000\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_7_descontinuidade.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_7_descontinuidade.jpg 750w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_7_descontinuidade-9x12.jpg 9w\" sizes=\"(max-width: 750px) 100vw, 750px\" \/>\t\t\t\t\t\t\t\t<\/a><figcaption>Figure 7 - Vertical discontinuity that controls the terminal zone of the cave (Photo: Afonso Rodrigues - GEM).<\/figcaption><\/figure>\n<p>In this area, the configuration of the cavity changes. The pressure tubes give way to two or three large, widened vertical discontinuities covered in coralloids. This final section has the appearance of vadose genesis. The ceiling of the passages is likely very close to the surface, and there is an impressive root crossing the main joint (or fault). Furthermore, a small draught (air current) is felt at the bottom, possibly from an inaccessible second entrance.<\/p>\n<p>Speleometry<\/p>\n<p>A new survey (topography) of the cave was carried out, yielding the following speleometric data:<\/p>\n<ul>\n<li> total development (length): 152m;<\/li>\n<li> horizontal projection (plan length): 133m;<\/li>\n<li> denivelation (Depth): -25m. <\/li>\n<\/ul>\n<p>The speleometric data is compatible with the topography provided by Bruno Pais.<\/p>\n<figure>\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/drive.google.com\/file\/d\/1WnAuC458BcrWRZCqCSLgA0RInUnxY-MY\/view\" target=\"_blank\"><br \/>\n\t\t\t\t\t\t\t<img loading=\"lazy\" width=\"700\" height=\"990\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Algar_da_Cancela_II_PLANTA.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Algar_da_Cancela_II_PLANTA.jpg 700w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Algar_da_Cancela_II_PLANTA-8x12.jpg 8w\" sizes=\"(max-width: 700px) 100vw, 700px\" \/>\t\t\t\t\t\t\t\t<\/a><figcaption>Figure 8 - Plan view of Algar da Cancela II (press to download in png format).<\/figcaption><\/figure>\n<figure>\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/drive.google.com\/file\/d\/1O9xw2GfFfxv_N0CNFvxM_FZlmquZtDZ6\/view\" target=\"_blank\"><br \/>\n\t\t\t\t\t\t\t<img loading=\"lazy\" width=\"990\" height=\"700\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Algar_da_Cancela_II_ALCADO.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Algar_da_Cancela_II_ALCADO.jpg 990w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Algar_da_Cancela_II_ALCADO-18x12.jpg 18w\" sizes=\"(max-width: 990px) 100vw, 990px\" \/>\t\t\t\t\t\t\t\t<\/a><figcaption>Figure 9 - Extended profile of Algar da Cancela II (press to download in png format).<\/figcaption><\/figure>\n<p>Rigging guide<\/p>\n<p>The rigging guide\/log for the cavity is shown in the profile (see Figure 9).<\/p>\n<p>Geological Setting<\/p>\n<p>According to sheet 27-C of the Geological Map of Portugal at a 1:50,000 scale (Manupella et al), the cave develops in the Camadas de Caba\u00e7os and Montejunto formation, dated from the Middle to Upper Oxfordian stage (Upper Jurassic Epoch).\nThe layers are locally quite folded, albeit irregularly, indicating a zone of greater deformation. This is not surprising given the proximity to the Arrife thrust fault (cavalgamento do Arrife), located about 650m south of the cave (see Figure 10). The area also shows several faults sub-parallel to the Arrife (NNW-SSE to NW-SE), although some later turn north or west.<\/p>\n<p>As a point of interest, the Arrife thrust fault, while causing a considerable controlling slope of about 300m, does not have the same verticality as other Arrife cliffs. This is because part of the slope consists of Upper Jurassic terrigenous deposits, which cannot maintain sub-vertical faces.<\/p>\n<figure>\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_10_Geologia.jpg\" data-elementor-open-lightbox=\"yes\" data-elementor-lightbox-title=\"Figura 10 - Implanta\u00e7\u00e3o da planta do Algar da Cancela II em extrato da folha 27-C da Carta Geol\u00f3gica de Portugal \u00e0 escala 1\/50000.\" data-e-action-hash=\"#elementor-action%3Aaction%3Dlightbox%26settings%3DeyJpZCI6MjE5NjcsInVybCI6Imh0dHBzOlwvXC9nZW0ucHRcL3dwLWNvbnRlbnRcL3VwbG9hZHNcLzIwMjVcLzEwXC9GaWd1cmFfMTBfR2VvbG9naWEuanBnIn0%3D\"><br \/>\n\t\t\t\t\t\t\t<img loading=\"lazy\" width=\"850\" height=\"1300\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_10_Geologia.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_10_Geologia.jpg 850w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_10_Geologia-8x12.jpg 8w\" sizes=\"(max-width: 850px) 100vw, 850px\" \/>\t\t\t\t\t\t\t\t<\/a><figcaption>Figure 10 - Location of the Algar da Cancela II plan on an excerpt from sheet 27-C of the Geological Map of Portugal at 1\/50,000 scale.<\/figcaption><\/figure>\n<figure>\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_11_Geologia.jpg\" data-elementor-open-lightbox=\"yes\" data-elementor-lightbox-title=\"Figura 11 - Implanta\u00e7\u00e3o da planta do Algar da Cancela II em extrato da folha 27-C da Carta Geol\u00f3gica de Portugal, a escala maior.\" data-e-action-hash=\"#elementor-action%3Aaction%3Dlightbox%26settings%3DeyJpZCI6MjE5NjgsInVybCI6Imh0dHBzOlwvXC9nZW0ucHRcL3dwLWNvbnRlbnRcL3VwbG9hZHNcLzIwMjVcLzEwXC9GaWd1cmFfMTFfR2VvbG9naWEuanBnIn0%3D\"><br \/>\n\t\t\t\t\t\t\t<img loading=\"lazy\" width=\"850\" height=\"1300\" src=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_11_Geologia.jpg\" alt=\"\" decoding=\"async\" srcset=\"https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_11_Geologia.jpg 850w, https:\/\/gem.pt\/wp-content\/uploads\/2025\/10\/Figura_11_Geologia-8x12.jpg 8w\" sizes=\"(max-width: 850px) 100vw, 850px\" \/>\t\t\t\t\t\t\t\t<\/a><figcaption>Figure 11 - Location of the Algar da Cancela II plan on an excerpt from sheet 27-C of the Geological Map of Portugal at bigger scale.<\/figcaption><\/figure>\n<p>Structural Control<\/p>\n<p>A gruta apresenta um controlo estrutural sobretudo pela atitude das camadas, com exce\u00e7\u00e3o da zona terminal. As camadas t\u00eam atitude aproximada N40E\/30E, seguindo a galeria ora a dire\u00e7\u00e3o ora a inclina\u00e7\u00e3o em tro\u00e7os aproximadamente perpendiculares. A principal dire\u00e7\u00e3o de desenvolvimento da galeria \u00e9 pr\u00f3xima da dire\u00e7\u00e3o das camadas. O tro\u00e7o terminal da galeria, por\u00e9m, \u00e9 controlado por descontinuidade de atitude aproximada N70W\/Subvertical, que por coincidir com falha cartografada (ver figura 11) consideramos uma falha.<\/p>\n<p>Genesis and Evolution<\/p>\n<p>The cave was formed in the phreatic zone according to B\u00f6gli's definition (1980). This is evidenced by the rounded section of the galleries, erosion scallops, ceiling cupolas, and ceiling channels.\nThe erosion scallops generally have an approximate length between 0.4 and 1.0m, with the most common length being between 0.6 and 0.7m.Most scallops are symmetrical, but some point towards the cave mouth, indicating an ancient direction of water circulation of NE-SW.<\/p>\n<p>The cave subsequently silted up, resulting in the abundant clay deposits that fill most of the gallery space. Then, due to a relative lowering of the base level, the cavity moved from the phreatic zone to the inactive vadose zone.<\/p>\n<p>Algar da Cancela II marks an ancient level of water circulation that is currently at an approximate elevation of 280-285m. The cave entrance may have been an ancient spring, as suggested by its phreatic appearance, proximity to the Arrife thrust fault, and the contact of the MCE with non-karstic terrain.\nWe recall the Alcobertas spring, located just over 3 km SW of Algar da Cancela II, which is a current permanent spring situated in a similar geological context (formed in Upper Jurassic terrain and near the contact of the MCE with non-karstic terrain).<\/p>\n<p>Conclusions<\/p>\n<p>Algar da Cancela II is a cave of phreatic origin, which marks an ancient circulation level, currently at an approximate elevation of 280-285m, and which developed in Upper Jurassic Limestones. The cavity has a total development of 152m, a horizontal projection of 133m, and a depth of -25m.The cave is primarily controlled by the strike of the layers and, in its terminal zone, by a fault. The cave entrance may have been an ancient spring.<\/p>\n<p>Fieldwork Team<\/p>\n<p>The fieldwork team consisted, in alphabetical order, of: Afonso Rodrigues (AESDA\/GEM\/CEAE), Catarina Teixeira (GEM), Filipe Alves (GEM), Filipe Castro (GEM), Paulo Lopes (GEM), and Pedro Cardoso (GEM\/NECA).<\/p>\n<p>Bibliography<\/p>\n<ul style=\"margin-right: 0px; margin-bottom: 0px; padding-right: 0.3em; padding-left: 2em; clear: both;\">\n<li>B\u00f6gli, A. (1980), Karst Hydrology and Physical Speleology, Springer-Verlag, Berlin Heildelberg New York.<\/li>\n<li>Crispim, J.A (1995). Din\u00e2mica C\u00e1rsica e Implica\u00e7\u00f5es Ambientais nas Depress\u00f5es de Alvados e Minde (Karstic Dynamics and Environmental Implications in the Alvados and Minde Depressions). PhD Thesis in Geology, specialty in Environmental Geology. Geology Department. Faculty of Sciences, University of Lisbon.<\/li>\n<li>Ferreira, Jaime Martins, (1962), Nota sobre o Algar da Cancela II (Note on Algar da Cancela II), Bulletin of the Portuguese Speleological Society, Vol. II, No. 1.<\/li>\n<li>Manupella, G., Barbosa, B, C.A., Azer\u00eado, Carvalho J,; Crispim, J., Machado S.; Sampaio J.; (2006). Carta Geol\u00f3gica de Portugal \u2013Torres Novas, Folha 27-C, \u00e1 escala 1:50000, e Nota Explicativa (Geological Map of Portugal \u2013 Torres Novas, Sheet 27-C, at 1:50,000 scale, and Explanatory Note), Instituto Nacional de Engenharia, Tecnologia e Inova\u00e7\u00e3o, Lisboa.<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>Algar da Cancela II 05 de Outubro de 2025 Rodrigues, Afonso 1\u00a0&#8211; Introdu\u00e7\u00e3o e Localiza\u00e7\u00e3o, Resenha Hist\u00f3rica, Descri\u00e7\u00e3o e Topografia Rodrigues, Paulo\u00a01,2,3 &#8211; Enquadramento Geol\u00f3gico, Controlo Estrutural e G\u00e9nese e Evolu\u00e7\u00e3o\u00a0 Grupo de Espeleologia e Montanhismo, Rua General Pereira de E\u00e7a, n\u00ba30, 2380-075 Alcanena N\u00facleo dos Amigos das Lapas Grutas e Algares\u00a0 Comiss\u00e3o Cient\u00edfica da [&hellip;]<\/p>\n","protected":false},"author":20,"featured_media":0,"parent":1574,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-21954","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/gem.pt\/1\/en\/wp-json\/wp\/v2\/pages\/21954","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gem.pt\/1\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/gem.pt\/1\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/gem.pt\/1\/en\/wp-json\/wp\/v2\/users\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/gem.pt\/1\/en\/wp-json\/wp\/v2\/comments?post=21954"}],"version-history":[{"count":0,"href":"https:\/\/gem.pt\/1\/en\/wp-json\/wp\/v2\/pages\/21954\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/gem.pt\/1\/en\/wp-json\/wp\/v2\/pages\/1574"}],"wp:attachment":[{"href":"https:\/\/gem.pt\/1\/en\/wp-json\/wp\/v2\/media?parent=21954"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}