National Geographic : 1961 Nov
age of the oceans and the possible drift of continents across the underlying mantle. Magnetic properties of successive layers may indicate whether the earth's magnetic poles have shifted radically. Flow of heat through the crust, measured during Mohole drilling, may reveal more about suspected move ments within the earth. Is our planet cooling, or still gaining heat from inner radioactive fuels? And there is the final goal-the stuff of the mantle itself, mysterious and elusive. "That Which Is Far Off..." Thus Project Mohole, fairly and ably be gun, promises new knowledge of the earth beyond all man's imagination. Two weeks after the San Diego tests, CUSS I drilled successfully in waters nearly four times as deep-11,700 feet down, 21/5 miles near Guadalupe Island to the south. This time it penetrated the mysterious second layer of the crust beneath the softer sediments, bringing up samples of volcanic basalt from 600 feet under the sea floor (below). Two to three years of study and tests still lie ahead before the Mohole itself is begun. The best site must be chosen. New equipment must be designed for the tricky operation of retracting the entire drill string, changing the diamond bit, and returning it to the same hole. A bigger ship must be found or built to carry the far greater weight of pipe and gear needed for the ultimate attempt. "We are asked whether a Mohole can be drilled at all," Mr. Bascom said. "With what we learned this year, we know it can be done." It would seem a direct enough reply to the question from Ecclesiastes (7:24): "That which is far off, and exceeding deep, who can find it out?" 697 I. S. GEOLOGICAL SURVEY © NATIONAL GEOGRAPHIC SOCIETY Historic sample from 560 feet under the sea floor in 11,700 feet of water off Gua dalupe Island shows a sharp boundary between sedimen tary and igneous layers. Scientists inspect the first cores. They seek answers to these questions: What is the earth made of? When did life begin in the seas? Paleontologists have been unable to span the gap be tween the record of simple Pre-Cambrian life and the relatively complex organ isms appearing at the be ginning of the Paleozoic era. Records of this gap may lie in rocks deep below the seas. When the drill, biting 560 feet into the bottom, struck rock formed by volcanic forces, did this basalt indi cate that molten material had flowed above deeper sediments? Or had a con tinental mass drifted across the mantle? Or was this the true floor of the primordial sea? Future tests may tell. Basalt core sample from Guadalupe site, split and polished, belongs to the Na tional Museum, Smithson ian Institution, Washington, D. C. Depth: 600 feet be low the sea floor.