The island of Fayal, also spelled Faial, is the nearest of the central Azorean islands to the Mid-Atlantic Ridge. The island is composed of a complex large andesitic-to-trachytic stratovolcano that contains a 2-km-wide summit caldera. Thick deposits of trachytic airfall pumice, pyroclastic flows, and lahars related to formation of the caldera cover the island. Formation of the steep-walled 400-m-deep caldera was followed by construction of fissure-fed basaltic lava fields and small volcanoes that form a peninsula extending to the west. This area is covered by the youngest volcanic products on the island. A submarine eruption at Capelinhos during 1957-58 created a new island that soon merged with the western peninsula.