This question can be answered by looking at the Mid Ocean Ridge. Being a mostly divergent boundary, the oceanic plates are pulling away due to tensional stress. One would assume this would leave a deep ocean trench as the plates pull away. This is not the case. As the plates pull away, igneous material (usually basalt) is produced upwards and immediately fills the void left by the separating plates. This new magma is at the very center of the Mid Ocean Ridge. The older magma that had been produced in this same method are on either side of this new material. As the plates pull apart, the old material is pulled with it. Gravity also pulls these older materials downward and away from the higher Mid Ocean Ridge.
When new crust is made, like at a spreading center, old crust must be destroyed, like at a subduction zone, where it is brought back into the inner earth and melted and recycled through.
In sea-floor spreading, the old oceanic crust is pushed away from the mid-ocean ridge as new molten material rises from the mantle. As the new material solidifies, it forms new oceanic crust, leading to the spreading of the seafloor and the continuous creation of new crust. The older oceanic crust eventually gets subducted back into the mantle at tectonic plate boundaries.
Crust is made from recycling old crust so that there is still the same amount. The earth doesn't expand because there is a cycle that keeps the proportions the same throughout the entire cycle.
Mid-ocean ridges are divergent plate boundaries where new oceanic crust forms as tectonic plates move apart. At these boundaries, magma rises from the mantle, cooling and solidifying to create new crust.
near ocean trenches.
When new crust is made, like at a spreading center, old crust must be destroyed, like at a subduction zone, where it is brought back into the inner earth and melted and recycled through.
The crust is new.
The older oceanic crust moves away from the spreading center and is eventualy subducted back into the mantle.
The older oceanic crust moves away from the spreading center and is eventualy subducted back into the mantle.
The older oceanic crust moves away from the spreading center and is eventualy subducted back into the mantle.
Because the old one is destroyed. So it doesn't expand.
In sea-floor spreading, the old oceanic crust is pushed away from the mid-ocean ridge as new molten material rises from the mantle. As the new material solidifies, it forms new oceanic crust, leading to the spreading of the seafloor and the continuous creation of new crust. The older oceanic crust eventually gets subducted back into the mantle at tectonic plate boundaries.
cause its cooler
how is this food and cooking? it is geography
Just as new oceanic crust forms at mid-ocean ridges, old oceanic crust is destroyed at subduction zones.
Continental crust is thicker, less dense, and composed mainly of granite, while oceanic crust is thinner, more dense, and primarily made of basalt. Continental crust is older and can be up to 3 billion years old, while oceanic crust is typically less than 200 million years old.
The older oceanic crust moves away from the spreading center and is eventualy subducted back into the mantle.