Word: sedimenting
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When geophysicists tag the rock strata under the ocean, they call the ocean water the first layer. On the bottom is the second layer: sediment and sedimentary rock averaging 1 km. thick. Below it lies the third layer, which seismic waves have proved to be made of unusually heavy rock. The third layer is normally unreachable, but scientists making a seismic survey in 1959 got hints that it might be exposed on the sides of the Puerto Rico Trench. In 1960 Dr. Earl Hays of Woods Hole took photographs showing fractured rock on the trench's north wall...
...John B. Hersey, chief scientist of the cruise, believes that the chunks with fresh faces were broken by the dredge out of the mysterious third layer. If so, they may show what the crust of the earth was like billions of years ago, before the infant ocean rained sediment...
...John Rosholt of the U.S. Geological Survey and Italian-born Dr. Cesare Emiliani, it depends on the fact that a tiny amount of uranium is dissolved in all sea water. When it slowly decays radioactively, it yields protoactinium 231 and thorium 230, both of which attach themselves to sediment particles and sink slowly to the bottom. There they in turn decay, but protoactinium 231 decays faster than thorium 230. The age of sediment on the ocean floor can therefore be determined by measuring the relative abundance of the two isotopes...
...proud, too much the unbending leopard on his own family crest, to be able to lick his wounds by joining those who inflict them. In the mid-span of his life he courts oblivion ("While there's death there's hope"), and measures out the ''sediment of grief which, accumulating day by day, would in the end be the real cause of his death...
...Francisco. Diving tests have shown that most of the hot material remains sealed off in the containers, but some leaks out, might yet show up in seafood. Oceanographers and marine biologists are studying the effects wrought on the radioactive graveyards by such phenomena as bottom currents, movement of bottom sediment and the upwelling of bottom waters. AEC is also concerned about such future needs as a program of international coordination (Britain now pumps its low-energy atomic garbage through a pipe into the Irish Sea) and the radioactivity that will remain in the oceans in the wake of nuclear-powered...