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Where in Continental rift zones are areas where the crust has been what?
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What do scientists believe that is happening to the segments of earths crust?
it has been washed into the oceans as the continental crust has eroded.
What is the main difference between continental plates and oceanic plates?
Oceanic crust is created on Mid ocean ridges and of basaltic composition. Oceanic crust is on average comparatively young as it is subducted into the mantle in subduction zones. Oceanic crust is denser and thinner than average continental crust.The composition and age distribution of continental crust is much more complicated than that of oceanic crust. It is on average less dense and much thicker than oceanic crust and its composition is roughly that of a tonalite (something similar to a granite but with less alkali feldspar). Apart from igneous rocks and metamorphic rocks, the sedimentary rocks add a lot to the variety of lithologies found on the continents (carbonates, evaporites, sandstones, shales, conglomerates, etc.).As opposed to oceanic crust, continental crust is not subducted into the mantle in large quantities but has been gradually accumulating over geologic timescales.
Is continental crust thinner than oceanic crust?
It is about 20 miles or 30 kilometers.
How are fossils useful evidence of continental drift?
Fossil are important to the Continental drift because fossils were found in areas where they should not have been found. Like across the world.
Can continental lithosphere subduct?
Not usually, as the rock they are made of (mostly granite) is too light to sink into the mantle (mostly denser basalt). Small fragments of continental crust can get entrained in a subducting oceanic plate and be dragged down into the mantle as that plate subducts. Where continental crust collides with oceanic crust, it always floats forcing the oceanic crust down and causing it to subduct. Where continental crust collides with continental crust, both plates crumple and compress dramatically, being forced upward into unusually high mountains (e.g. the Himalayas) and downward into deep continental roots that support the weight of those mountains. Nothing subducts in this case. But whole continental plates subducting does not happen, while much more oceanic plate area has been subducted in the history of the earth than the total surface area of the earth.
Why havent older ocean rocks been discovered?
Oceanic crust is eventually destroyed in subduction zones. Although oceanic crust has been forming on Earth for over 4 billion years, all of the sea floor older than about 200 million years has been recycled by plate tectonics. Continental crust is not subducted and destroyed, so very old continental rocks have survived.
Why is the oldest rock on planet earth found on continental plates not oceanic plates?
Oceanic crust is constantly being recycled. New oceanic crust is formed at mid ocean ridges while old ocean crust is destroyed at subduction zones. As a result there is little oceanic crust that is older than 200 million years. Continental crust does not get destroyed by subduction, so much of it has been around since the Precambrian time.
What do scientists believe that is happening to the segments of earths crust?
it has been washed into the oceans as the continental crust has eroded.
Is the theory of the continental drift true?
Continental Drift is an obsolete name for the theory of Plate Tectonics and yes, it is true. It has been proved in many ways, by comparing the composition of oceanic crust and its ages with that of the continental crust, by plotting the reversals of magnetism in the oceanic crust and many other ways.
What is the main difference between continental plates and oceanic plates?
Oceanic crust is created on Mid ocean ridges and of basaltic composition. Oceanic crust is on average comparatively young as it is subducted into the mantle in subduction zones. Oceanic crust is denser and thinner than average continental crust.The composition and age distribution of continental crust is much more complicated than that of oceanic crust. It is on average less dense and much thicker than oceanic crust and its composition is roughly that of a tonalite (something similar to a granite but with less alkali feldspar). Apart from igneous rocks and metamorphic rocks, the sedimentary rocks add a lot to the variety of lithologies found on the continents (carbonates, evaporites, sandstones, shales, conglomerates, etc.).As opposed to oceanic crust, continental crust is not subducted into the mantle in large quantities but has been gradually accumulating over geologic timescales.
How long has the continental crust been evolving?
Over the last 4 billion years.
Why is the oldest ocean crust only 150 million years old?
Because the oldest parts reach the continental crust and then the ocean floor sinks beneath the continental crust, into the mantle.
Why does the thickness of the Earth's crust range from 6 to 70km?
Earth's crust varies in thickness due to differences in composition and the effects of plate tectonics. Oceanic crust is thinner and more dense than continental crust, and thinnest where plates are diverging from each other. Continental crust is thickest at mountain ranges, where the crust has been thickened by plate collision or thermal uplift.
Rocks in continental crust are as old as years?
The oldest rock formations of the continental crust have been dated at 4.3 billion years of age, although the findings are encountering a bit of skepticism.
What is the oceanic crust and continental crust?
underlies the ocean floor
When has the continental drift been?
The continents began drifting since the Earth's crust cooled and they continue to do so.
Is continental crust thinner than oceanic crust?
It is about 20 miles or 30 kilometers.
