Gruta do Carvão: Ponta Delgada’s Hidden Basaltic Lava Tube
The Gruta do Carvão, a basaltic lava tube carved by molten rivers of magma, lies hidden beneath the western edge of Ponta Delgada on São Miguel Island in the Azores. Formed approximately 12,000 years ago when lava from the Serra Gorda flows reached the ocean and drained, it now stretches some 1,650 meters underground, though…