National Geographic : 1975 May
Like an elephant's trunk, a foot-wide lava tube noses down an incline two yards in front of Alvin's collecting basket (left). Scientists found the youngest and most distinct lava forms along the rift's axis. As they moved to the east or west, a chaotic landscape of shattered sculpture unfolded, evidence of the earth's movement away from the frontier of crustal genesis. Pillow of lava pushed two feet above the surface of a tube (right). Later, gorgonian coral took hold. The snowstorm of sediment was kicked up by Alvin's propeller. A scientist de scribed working in such condi tions: "It's like exploring the Grand Canyon at night in a blizzard with a flashlight." Telltale interior of a shattered lava tube reveals its intricate his tory. After an initial flow created the hollow conduit, subsequent streams of lava moved through, leaving ledges or ridges much as rings in a bathtub show succes sive water levels.