A Science Odyssey
People and Discoveries

Great Global Rift is discovered

After World War I, Germany was suffering from the weight of debt imposed by war reparations and a devastated economy. German chemist Fritz Haber had read reports of an analysis showing that 65 mg of gold could be extracted from a metric ton of sea water. Haber proposed extracting gold from international waters as a way to ease Germany's economic plight. This seemed like a good idea and it caught on, though another, more modern analysis showed that the gold concentration was far lower and changed the nature of the maritime venture. In 1925, Germany outfitted a boat and set out for two years to systematically and scientifically look at the oceans -- and to show the flag, since the Versailles Treaty had banned German navy boats from foreign ports. This expedition was the first use of closely spaced echo sounders to map deep sea topography and the first to reveal the extent of the sea floor's rugged terrain. The expedition also found that a continuous mountain-like ridge runs through the Atlantic to the southwest of Africa. Unfortunately it was not realized at the time that this finding supported Alfred Wegener's theory of continental drift.

That ridge, it was later discovered, extended through the major oceans of the world. It is now called the Mid-Ocean Ridge. In 1953, American physicists Maurice Ewing (1906-1974) and Bruce Heezen (1924-1977) discovered that through this underwater mountain range ran a deep canyon. In some places the canyon, called the Great Global Rift, came very close to land. The rift appeared to be breaks in the earth's crust, but perfectly fitted breaks, like joints made by a carpenter. The rift outlined chunks of the earth's crust, which were named tectonic (from a Greek word for "carpenter") plates. Six large and several smaller plates make up the surface of the globe. Most of the world's earthquakes and volcanoes occur at the plates' edges. The large plate containing most of the Pacific Rim accounts for 80 percent of the earthquake energy of the planet.

Ewing and Heezen's finding marked an explosion in data from newly advanced technology that revolutionized geology. Harry Hess was inspired by the findings to look back at soundings he'd made during the war on a U.S. submarine. His evidence and the work of Frederick Vine and Drummond Matthews brought the data together in the theory of sea-floor spreading.

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