page_title: Algar do Carvão
section_title: Geography
hierarchical_section_title: Algar do Carvão / Geography
caption_attribution_description: Português: Algar do Carvão, Ilha Terceira, Açores - Portugal.
context_page_description: The Algar do Carvão is an ancient lava tube or volcanic vent located in the central part of the island of Terceira in the Portuguese archipelago of the Azores. It lies within the civil parish of Porto Judeu in the municipality of Angra do Heroísmo.
context_section_description: Terceira is the site of four large volcanoes (Pico Alto, Santa Bárbara, Guilherme Moniz, and Cinco Picos) grouped along a basaltic fissure zone that transects the island from northwest to southeast. The Algar do Carvão is directly associated with the caldera of the Guilherme Moniz volcano, but it is part of the same complex as Santa Barbara to the west, Pico Alto to the north, and Guilherme Moniz, which is a short distance to the south of the Algar do Carvão site. Algar do Carvão is situated at 583 metres (1,913 ft) above sea level.
  The 40.5 hectares (4,360,000 sq ft) extent was classified as a Regional National Monument (Portuguese: Monumento Natural Regional) due to its peculiar volcanological characteristics, in addition to its environmental ecosystem. The mouth of the Algar consists of a 45 metres (148 ft) vertical passage to the interior, that reaches a ramp of debris and gravel. From here there is another decline to the clear waters of the interior pool, approximately 90 metres (300 ft) from the level surface. The pool is supported by rainwater, and can reach as deep as 15 metres (49 ft) depth or become dry in summer months, owing to little or no precipitation.
  The cave itself is remarkable for the unique mineralogical characteristics of its silicate stalactites.
caption: A view through the Boca do Algar (Mouth of the Cavern)
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