Word: sedimentation
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Dates: during 1970-1979
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...water temperatures near these ridges are considerably higher than those elsewhere in the ocean. In addition, there are ocean-floor fault lines or cracks that were apparently caused by movement of the seabed itself. Although the oceans are billions of years old, sonar measurement of the depth of accumulated sediment indicated that the sea floor is no more than a few hundred million years old; the deposit of sediment should be much thicker...
...hardens into a more rigid layer called the lithosphere. When new lava oozes out, it attaches itself to the older lithosphere and continues to move laterally from the mid-ocean ridges. Millions of years and thousands of miles later, the moving lithosphere plunges back into the earth, carrying its sediment with it and forming the deep ocean trenches found at the edge of continents. Hess's theory at last had provided a workable mechanism needed by continental-drift theorists. It was the sea floor itself that moved. Like giant conveyor belts, the ocean bottoms transported the earth...