Word: crustal
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...MOST POWERFUL EARTHQUAKES EVER to hit the U.S. -- each topping 8.0 on the Richter scale -- struck near the town of New Madrid, Missouri, in the early 1800s. It is hardly an obvious location. The theory of plate tectonics says quakes should happen most often along the edges of crustal plates, pancakes of rock a few score miles thick and thousands of miles across, which carry the continents on their backs as they slide across the semimolten mantle below. The plates ride over each other or grind together, and the earth shakes. But New Madrid is right in the middle...
What is more, the restless tectonic plates spawn volcanic eruptions, which spew carbon dioxide into the air. The increase in atmospheric carbon dioxide results in a greenhouse effect, which traps the sun's energy, causing temperatures on land and in the sea to rise markedly. Conversely, crustal movement may allow frigid ocean currents from the poles to invade tropical waters, leading to a worldwide drop in temperatures. Those species that cannot adapt to the earth's erratic behavior simply succumb. To many paleontologists, as well as geologists, it seemed to make sense...
...earth in volume but has a mass only 14 1/2 times as great, has a liquid core. Some scientists speculate, however, that the magnetic field may be generated by an electrically charged ocean covering the planet. Some of the larger moons apparently have, or at one time had, crustal movements that created the fault zones and valleys evident in the Voyager photographs. Geologist Laurence Soderblom, for one, was surprised at what he called "the degree of geological activity on the Uranian satellites." Along some of the faults on Titania, he said, "some sort of material is leaking out of fractures...
...cause of the changes can be traced, at least in part, to plate tectonics, the movement of the great crustal plates that ride on the earth's semimolten mantle and provide its solid outer shell. Some 45 million to 50 million years ago, the plate that carries the Indian subcontinent was pushing up into the underbelly of Asia, slowly thrusting up the massive mountain range now called the Himalayas. This new barrier to global wind circulation helped change weather patterns, altering average temperatures around the world. By about 14 million years ago, climates that had been tropical had turned largely...
...meters (9,000 feet) below the waves, scientists aboard vessels from the Woods Hole Oceanographic Institution were looking for underwater geysers or "hot spots." They were conducting their search along the Galapagos Rift, where lava from the earth's molten interior rises toward the surface between two great crustal plates. Such depths are thought to be relatively barren of nutrients-and thus of life. But photographs from the deep revealed small areas, each around a warm spring, that were teeming with clams, mussels, tube worms and scavenger crabs. The probable explanation for the profusion of these organisms, announced last...