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The surface of the Earth isn't entirely solid; like the fragments of an eggshell, the crust is in pieces. These pieces, called "plates", can move very slowly across the surface. The North American plate, for example, is moving west away from Europe at a speed of an inch or so per year.
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What are some characteristics of earths lithosphere?
Tectonic plates are the sections of the earth's crust which move about. You get Continental plates (with continets on top) and oceanic plates (with oceans on top). Continental ones are less dense, so they "float" on top of the denser oceanic plates whenever they collide. Continental is made of granite, whereas oceanic is made of basalt, due to the rapid cooling of the magma as it meets the sea. Because the oceanic is being constantly renewed, it isn't very old - only about 180 million years, whereas the continental crust is up to 4 billion years old.
What is the primary reason that the continential crust stays on top of the oceanic crust?
The primary reason continental crust remains above oceanic crust is its lower density. Continental crust is primarily composed of lighter, less dense rocks like granite, while oceanic crust is denser, made mostly of basalt. This difference in density causes the buoyant continental crust to "float" on the denser oceanic crust beneath it, resulting in the continental crust being elevated above sea level.
Why does the oceanic sink beneath continental crust at convergent boundaries?
The continental crust is less dense than the oceanic crust. That's the reason we find that the oceanic crust sinks (subducts) beneath the continental crust.Continental crust is less dense than oceanic crust and so cannot sink below it.
Are there plates underwater?
Yes, the entire world is covered in tectonic plates, however, the oceanic plates are much thinner generally than continental plates, and it is for this reason that hot spots (places on the inside of a plate that are weak enough to permit the passage of magma from the mantle, see Hawaii). This can also cause interesting dynamics at plate bounderies, for instance, on the west coast of the United States the pacific plate (oceanic) and the north American plate (continental) are colliding (at an angle). The thinner pacific plate slips under the thicker north American plate leading to mountain formation and volcanic activity.
Is oceanic crust wider than continental crust?
If you meant thicker, the answer is no: Continental crust is much thicker than Oceanic crust. This is because the oceanic crust is formed very quickly, at an ocean ridge, for example, where the lava gradually erupts. The continental crust, on the other hand, is like a river delta: over time, it grows in height as more material is added on top (by volcanoes and other intrusions, as well as other uplifting processes). The reason why we can't touch the Moon is because uplift and eruptions are balanced by weathering and erosion. Therefore, the thickness is regulated by an equilibrium, and this causes the crust to be thick. The thickness of the oceanic crust is not regulated in such a way, but additions to its thickness are irrelevant as the oceanic crust is very quickly subducted again. Millions of years ago, there was a small sea between Britain and the Laurentine continent. This consisted of Oceanic crust. It was then very quickly consumed again when the plates changed their direction. The same could happen, in theory, to the Atlantic Ocean. Only time will tell...
What happens when a plate of oceanic crust collides with a plate of the continental crust and why does this happen?
When oceanic crust collides with continental crust, the denser oceanic crust is forced beneath the continental crust in a process called subduction. This happens because oceanic crust is heavier, colder, and more dense than continental crust, making it susceptible to being subducted under the lighter continental crust. This collision can result in the formation of mountain ranges, volcanic arcs, and deep ocean trenches.
When a continental crustal plate collides with an oceanic crustal plate the continental crust is forced to move over the oceanic crust What is the primary reason that the continental crust stays on?
The continental crust is less dense and thicker than oceanic crust, which allows it to stay on top during a collision. The low density and greater thickness of continental crust help it resist subduction beneath the oceanic crust.
What are some characteristics of earths lithosphere?
Tectonic plates are the sections of the earth's crust which move about. You get Continental plates (with continets on top) and oceanic plates (with oceans on top). Continental ones are less dense, so they "float" on top of the denser oceanic plates whenever they collide. Continental is made of granite, whereas oceanic is made of basalt, due to the rapid cooling of the magma as it meets the sea. Because the oceanic is being constantly renewed, it isn't very old - only about 180 million years, whereas the continental crust is up to 4 billion years old.
Why does the oceanic sink beneath continental crust at convergent boundaries?
The continental crust is less dense than the oceanic crust. That's the reason we find that the oceanic crust sinks (subducts) beneath the continental crust.Continental crust is less dense than oceanic crust and so cannot sink below it.
Why is there a frequency of earthquakes and volcanoes?
The reason why is because the tectonic plates never stop moving. When one plate collides with another it causes volcanoes and earthquakes to occur.
Why is the main reason that oceanic crust is heavier than continental crust?
Oceanic crust is mafic in composition and continental crust is felsic in composition. Mafic minerals generally have a higher density than felsic minerals and therefore, the oceanic crust is heavier.
Are there plates underwater?
Yes, the entire world is covered in tectonic plates, however, the oceanic plates are much thinner generally than continental plates, and it is for this reason that hot spots (places on the inside of a plate that are weak enough to permit the passage of magma from the mantle, see Hawaii). This can also cause interesting dynamics at plate bounderies, for instance, on the west coast of the United States the pacific plate (oceanic) and the north American plate (continental) are colliding (at an angle). The thinner pacific plate slips under the thicker north American plate leading to mountain formation and volcanic activity.
What is the primary reason why the oceanic crust subducts below the continental crust and not vice versa when they collide together?
The oceanic crust subducts beneath the continental crust due to its higher density. Oceanic crust is basaltic and has a specific gravity of 3.3. Continental crust is granitic and has an average specific gravity of 2.9.
Does continental crust have a greater density than oceanic crust?
Yes, that is the reason oceanic crust is at a lower elevation compared to continental crust. Oceanic crust sub-ducts under the less dense continental crust. Continental crust is much older than oceanic crust, because oceanic crust is constantly being destroyed and created.
Is oceanic crust wider than continental crust?
If you meant thicker, the answer is no: Continental crust is much thicker than Oceanic crust. This is because the oceanic crust is formed very quickly, at an ocean ridge, for example, where the lava gradually erupts. The continental crust, on the other hand, is like a river delta: over time, it grows in height as more material is added on top (by volcanoes and other intrusions, as well as other uplifting processes). The reason why we can't touch the Moon is because uplift and eruptions are balanced by weathering and erosion. Therefore, the thickness is regulated by an equilibrium, and this causes the crust to be thick. The thickness of the oceanic crust is not regulated in such a way, but additions to its thickness are irrelevant as the oceanic crust is very quickly subducted again. Millions of years ago, there was a small sea between Britain and the Laurentine continent. This consisted of Oceanic crust. It was then very quickly consumed again when the plates changed their direction. The same could happen, in theory, to the Atlantic Ocean. Only time will tell...
What was the main reason scientists rejected Wegener's theory of continental drift?
One main reason scientists rejected Wegener's theory of continental drift was the lack of a plausible mechanism to explain how continents could move through the oceanic crust. Additionally, there was insufficient evidence at the time to support the idea of continents moving over time. The theory also faced criticism due to Wegener's background as a meteorologist, not a geologist.
What is the reason of the continental drift?
First, the continents do not drift! The theory of continental drift was based on observations of how the outlines of different continents appear to fit like pieces of a jigsaw puzzle and that when so fitted various ancient mountain ranges, etc. align from one continent to another. But for them to 'drift' they would have to 'plow' through the solid rock of the ocean floor, which is clearly not happening. The theory of continental drift was long ago discarded and replaced as new evidence was uncovered.The speculation that continents might have 'drifted' was first put forward by Abraham Ortelius in 1596. The concept was independently and more fully developed by Alfred Wegener in 1912, but his theory was rejected for lack of a mechanism.Following WW2 the US Navy made a series of observations showing symmetrical bands of magnetic field reversals on opposite sides of the midocean ridges. Because this information had value for military navigation, it was kept classified into the 1960s. When this information was made available to geophysicists, it confirmed key parts of the theory of plate tectonics (originally proposed in 1953).The idea of continental drift has been subsumed by the theory of plate tectonics, which explains how the continents appear to move. Convection currents in the semisolid mantle rock drag both continental and oceanic plates that float above the mantle around. The light granitic continental plate material tends to float higher, while the denser basaltic oceanic plate material tends to float lower so if they collide the continental plate will override the oceanic plate, causing it to subduct under the continental plate down into the mantle. If identical type plates collide the plates crumple and fold causing mountain ranges to form.The important thing to realize is the continents are not drifting, the tectonic plates (both continental and oceanic) of the crust are floating on the moving top surface of the mantle.
