Word: semimolten
(lookup in dictionary)
(lookup stats)
Dates: during 1970-1979
Sort By: most recent first
(reverse)
...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...
Mount Usu had last erupted in 1945. Since then, magma, or semimolten rock from the mantle surrounding the earth's core, had been slowly and quietly rising through cracks under the peak of the mountain, building up tremendous pressures and triggering repeated earth tremors that rocked Hokkaido. Finally, on Aug. 7, the 725-meter (2,400-ft.) Usu awakened with a roar like that of a bomb. A huge black cloud soared to a height of 12,000 meters (39,000 ft.). A dense shower of gray ash and chunks of porous, rock-like pumice poured...
...tectonics-which offers an elegant, comprehensive explanation for continental drift, mountain building and volcanism-seems finally to have clarified the underlying cause of earthquakes. It holds that the surface of the earth consists of about a dozen giant, 70-mile-thick rock plates. Floating on the earth's semimolten mantle and propelled by as yet undetermined forces, the plates are in constant motion. Where they meet, friction sometimes temporarily locks them in place, causing stresses to build up near their edges. Eventually the rock fractures, allowing the plates to resume their motion. It is that sudden release of pent...
...theoretical basis for things like submarine geology and attempts to study the underwater mountain range that bisects the Atlantic. Nor does he slight the host of others who have mapped the ocean bottoms, peered into smoking volcanoes or attempted to drill through the earth's crust to the semimolten mantle that surrounds its liquid core. Along the way, Sullivan scatters suggestive pieces of evidence with a skill that would do credit to Agatha Christie. He points out that the ancestors of certain North American animals seem to have come to their new home from Asia, something they could...
...crews of the subs would have seen giant volcanoes like those in Hawaii. But they spotted only small mountains-a sign of minor uplifting by forces beneath the earth's crust. The new observations, he explained, suggest that the continents are being pulled apart and hauled along by semimolten rock moving like two giant conveyor belts in opposite directions...