Algar do Carvão (Coal Pit)
Posted by: 
NFreitas
N 38° 43.527 W 027° 13.364
26S E 480638 N 4286333
Algão do Carvão in Terra Brava, center of Terceira island.
Waymark Code: WMVQH
Location: Portugal
Date Posted: 10/19/2006
Views: 120
Classification: Lava tube
Dimension: L=100m. VR=90m.
Open: 1 to 14 June: 15:00 - 17:00 / 15 June to 15 September: 14:45 - 17:45 / 16 to 30 September: 15:00 - 17:30 / 1 to 13 October: 15:00 to 17:00.
For more information call: (+351) 295212992
History:
1893-discovered.
1963-exploration completed.
1968-opened as a show cave.
2004-cave entrance building and interior renovated by the mountaineering club Os Montanheiros.
Description:
Algar do Carvão is a huge, about 100m long lava tube, which is the remains of a some 2000 year old volcanic eruption of the nearby Terra Brava (707m asl). The cave is the now empty tunnel of a lava flow. The name means coal pit in English, and was given to the cave because of the cave walls of dark black lava. Of course there is no coal found on this islands.
Very astonishing is the fact, that this volcanic cave contains stalactites and stalagmites. They were formed by silica, soluted from the lava, not by calcite as in karst caves. This is really exceptional, and the result of a special chemistry of the lava.
The cave is entered by going down stairs inside a shaft, a former vent of the lava flow. The end of the tour is a subterranean lake, formed by rain water. Depending on the season and the amount of rain water, the lake can be up to 15m deep. The whole cave is spacious, the passage is up to 45m in diameter.
The cave and the surrounding area was declared a natural monument after the initiative of the mountaineering club Os Montanheiros.
Close to the cave are the Furnas do Enxofre, sulfuric springs, well worth a visit. The best time for a visit is early in the morning, as the area gets very hot when the sun shines on the black rocks.
At the cave starts a trail which goes around the Terra Brava. It is said to be probably the most beautiful walk on Terceira. But be carefull with bulls, which are bred for bullfights. The walk takes four hours.
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Visit Instructions:
• Include a photo of the Artificial Cave if possible.