Submarine Volcanic Products

Abstract

The great bulk of new ocean floor created at oceanic spreading ridges, such as the Mid-Atlantic Ridge in the FAMOUS area, is composed of pillowed basaltic lava flows. Such lava flows have been previously studied at the spreading ridges by examination of dredge hauls and photographs taken from equipment lowered from surface ships. Outward from the spreading axis, where younger sediments cover the volcanic terrain, the deep sea drilling program of the GLOMAR CHALLENGER has verified that the dominant layer underlying the sediment is composed of pillow lava. This characteristic type of lava also is dominant in the submarine part of mid-ocean volcanoes such as Hawaii, and is important in the submerged part of the island arc volcanoes. Pillowed lava flows erupted beneath water likely comprise the most voluminous form of volcanic rock on earth.