Word: shallowing
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...latest American Journal of Science, F. Stearns MacNeil of the U.S. Geological Survey adds up the old clues to get a new theory: the rings were formed on dry land and later sank below the sea. He believes that coral and other sea organisms, growing on a shallow bottom, will build up a flat-topped reef (like many that exist today). In some cases, he says, such reefs were raised above the water, probably by changes of sea level because of ice ages, to become full-fledged islands. Then furious tropical rain went to work on the porous coral, dissolving...
...comparatively low centers could very well have been formed by the process he describes. Second, and even more convincing, the theory has survived a realistic laboratory test. A block of limestone, he reports, sprayed with dilute hydrochloric acid to approximate the effect of long-continued rain, erodes into a shallow saucer with a raised...
...Here We Are!" Back in the Permian (pre-dinosaur) period, 200 million years ago, the south central part of the U.S. and much of the present Gulf of Mexico was covered by a shallow sea, connected with the open ocean by an even shallower strait. The climate must have been hot and dry, and the sea evaporated rapidly, drawing fresh salt water in through the strait. Its brine became saturated and deposited crystalline salt, which eventually formed a bed thousands of feet thick...
Later the climate grew wetter, and the rivers cleared the shallow sea of its heavy brine. Some of the salt on the bottom probably dissolved, but the rest was protected by sediment washed down from the land. As the sediment grew thicker, it pressed on the underlying salt, and the salt (comparatively light and plastic) billowed up through it like slow-motion bubbles rising in a viscous liquid...
...DeLong drilling platform looks like an engineer's doodle turned into steel. It is a shallow-draught barge. Running through vertical holes near its sides are eight steel caissons. When the barge is being towed through shallow water, they stick up like lofty smokestacks. At the drilling site they are dropped, poking their ends into the bottom...