GEOLOGY
GEOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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subsides at the trenches, polar reversal
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emerges from the rift valley, magma pushing up from the asthenosphere
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emerges from the mid-ocean ridge, basaltic orientation in the trenches
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all of the above may be correct at different times
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Detailed explanation-1: -The theory of seafloor spreading explains that molten material moves in at the boundaries between tectonic plates pushing them apart as new oceanic crust is created. This process is called seafloor spreadingand it occurs at divergent boundaries.
Detailed explanation-2: -In the 1960s, geologist Harry Hess proposed that the sea floor was moving outward from the midoceanic ridges. His theory of sea floor spreading maintained that new basaltic oceanic crust forms at a midoceanic ridge and is slowly pushed away on both sides toward the continents as more new crust is produced.
Detailed explanation-3: -The idea that the seafloor itself moves and also carries the continents with it as it spreads from a central rift axis was proposed by Harold Hammond Hess from Princeton University and Robert Dietz of the U.S. Naval Electronics Laboratory in San Diego in the 1960s. The phenomenon is known today as plate tectonics.
Detailed explanation-4: -Hess envisaged that oceans grew from their centres, with molten material (basalt) oozing up from the Earth’s mantle along the mid ocean ridges. This created new seafloor which then spread away from the ridge in both directions.