Tuzo Wilson Seamounts numerous smaller vents, with a total edifice volume of about 12 km. The lava emitted in eruptions at the Tuzo Wilson Seamounts is made of basalt, a common gray to black or dark brown extrusive volcanic rock low in silica content (the lava is mafic) that is usually fine-grained due to rapid cooling of lava. Glassy pillow lava is found at the seamounts, a type of rock typically formed when basaltic lava emerges from a submarine volcanic vent. The viscous lava gains a solid crust on contact with the water, and this crust cracks and oozes additional large blobs or
Lava tube and lava channels on the flanks of Olympus Mons. Partially collapsed lava tubes are visible as chains of pit craters, and broad lava fans formed by lava emerging from intact, subsurface tubes are also common. Lava tube A lava tube is a natural conduit formed by flowing lava which moves beneath the hardened surface of a lava flow. Tubes can drain lava from a volcano during an eruption, or can be extinct, meaning the lava flow has ceased, and the rock has cooled and left a long cave. A lava tube is a type of lava cave formed when a