The islands that comprise it were formed by volcanic activity associated with the existence of the Galapagos Hot Spot (a volcanically active hot spot west of the Galapagos Islands, approximately 150 km in diameter). Lava flowing from the hot spot formed the Galapagos Islands.
The islands are mostly the summits of individual volcanoes (Isabel has six peaks). The Galapagos volcanoes are shield volcanoes, whose eruptions are not violent, with rare and very hot alkaline lava coming from their interiors. The world's largest shield volcano lies at the bottom of the Pacific Ocean, and its only visible remnants are the Gardner Pinnacles, two small rocky islands in the Hawaiian archipelago.
