Earths magma sculpted valleys and mountains 180 mln years ago: Study

December 4th, 2007 - 6:24 pm ICT by admin  

Washington, Dec.4 (ANI): A professor of earth and planetary sciences at the Johns Hopkins University who challenged the century-old concept that the Earth’s outer layer formed when crystal-free molten rock called magma oozed to the surface from giant subterranean chambers hidden beneath volcanoes, has taken his analysis further in the decade following his discovery.
Using the windswept McMurdo Dry Valleys of Antarctica as his “walk in” laboratory, geologist Bruce Marsh now claims that an extensive system of vertically interconnected smaller sheet-like chambers did more than simply transport or supply magma and crystals to form the Earth’s surface.
According to Marsh, the system, known as a “magmatic mush column,” which exists beneath all of the world’s major volcanic centers, pushed magma up through the earth, fracturing its crust in such a way as to provide a sort of “template,” and thereby, facilitating the sculpting a series of valleys and mountain ranges through erosion.
“As the magma made its way to the surface, the pressure broke the crust up into pieces. That fracturing reflected a pattern of stress in the same way that a windshield put under pressure will eventually fracture and the pattern of the broken glass would reflect where the stress was originally applied, claims Marsh.
“Magma then seeped in and ‘welded’ the fractures, sealing them temporarily until erosion in the form of snow, rain, ice and wind went to work on these weaknesses, carving out valleys, mountains and other landforms that we see there today and marking where the solidified magma originally was,” he adds.
Marsh said that, in Antarctica, both of these functions date back at least 180 million years to the time when the continents split apart.
“It’s one of those situations where, usually, never the twain shall meet, but they do in this case,” the earth scientist said.
The Dry Valleys makes an ideal place to study these systems because it was eroded into its present form millions of years ago and has, unlike the rest of Earth’s surface, undergone very little subsequent erosion.
Marsh and his colleagues George Denton of the University of Maine and David Marchant of Boston University call this region “a relic landscape,” because it is the only known place on Earth that looks almost exactly as it did millions of years ago.
Marsh has been working to understand the deep underground systems below the Earths surface for over 25 years.
Marsh described his latest findings to fellow scientists at a recent meeting of the American Geological Society. (ANI)

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