Magazine article USA TODAY

New Theory of Continent Formation

Magazine article USA TODAY

New Theory of Continent Formation

Article excerpt

There are major flaws in conventional beliefs about the process that formed and continues to shape the continents, maintains Bruce Marsh, professor of earth and planetary sciences, Johns Hopkins University. The process in which molten rock, or magma, migrates to the planet's surface in meandering columns of molten mush is more involved than geologists had thought.

The pea-sized crystals that appear in solidified magma deposits settle to the floors of the molten deposits, distilling and enriching the magma and allowing it to form the material from which the continents eventually are produced. The larger the crystals, the more the magma is enriched. Geologists had postulated that these crystals grew and collected, as a sort of precipitate, in the cooling magma, but Marsh's findings have led him to a much different explanation.

The large crystals actually were transported from great depths by the columns of molten slurry, he has concluded. After discovering that detail about the origin of the crystals, he was able to use the golden-green stones as tracers, tracking the chemical and physical path that the magma took as it flowed up to the surface in Antarctica.

Over millions of years, molten rock surged up from deep reservoirs, forming and pushing apart the continents, ultimately making it possible for higher, terrestrial animals to evolve. The fulminating magma also might have played a vital role in the beginning of life on the primeval Earth, as the most primitive organisms congregated around hydrothermal vents on ocean floors. …

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