Algar do Carvão

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.HistoryThe existence of the cavern had been known for a long time, but the depth and lack of ambient light, made any descent difficult, owing to the vertical descent, and delayed any real exploration.On 26 January 1893, the first descent, "...with the use of a simple rope, was accomplished by Cândido Corvelo and Luis Sequeira."The second descent was made in 1934, by Didier Couto, who produced the first rough map of the interior. This drawing, based on visual observations alone (rather than measurements), turned out to be quite accurate.On 18 August 1963, a group of enthusiasts organized a descent using a "chair" platform suspended on a nylon line and, later, a harness.With the advent of portable lighting systems, it was possible to re-examine the observations first-hand, including the most remote and narrow sections of the cavern. The site was open to the public in the late 20th century, through weekly organized tours (except weekends and holidays) through the summer (from May to September). Access to the site is also possible through the Montanheiros (Mountaineers) organization, the group responsible for matters associated with the Algar.ToponymyThe word, algar, is a Portuguese word that denotes a natural cavity in the earth that, unlike most caves or caverns, is more vertical in its orientation, like a well. The Portuguese word derives from the Arabic word, al-Gar, which means "the crease", while Carvão means "coal" in Portuguese. The Algar do Carvão is not a source of coal, and the term carvão has also been used in the Portuguese vernacular akin to "blackened", "sooty" or "burnt", referring to the dark composition of the rocks.