Seafloor spreading is a geologic process in which tectonic plates—large slabs of Earth’s lithosphere—split apart from each other . ... As tectonic plates slowly move away from each other, heat from the mantle’s convection currents makes the crust more plastic and less dense.
What is sea floor spreading theory?
seafloor spreading, theory that oceanic crust forms along submarine mountain zones , known collectively as the mid-ocean ridge system, and spreads out laterally away from them. ... As the magma cools, it is pushed away from the flanks of the ridges.
What is the theory of seafloor spreading quizlet?
In sea-floor spreading, the sea floor spreads apart along both sides of a mid-ocean ridge as new crust is added . ... Several types of evidence supported Hess’s theory of sea-floor spreading: eruptions of molten material, magnetic stripes in the rock of the ocean floor, and the ages of the rocks themselves.
Who proposed the theory of seafloor spreading?
Harry Hess : One of the Discoverers of Seafloor Spreading.
What are the main points of the seafloor spreading theory?
Seafloor spreading is the mechanism by which new seafloor lithosphere is constantly being created at mid-ocean ridges . This theory, introduced by Harry Hess, was proven as patterns of magnetic field polarity preserved in seafloor basalt and by age dating of the rocks.
What are the three types of seafloor spreading?
There are three types of plate-plate interactions based upon relative motion: convergent, where plates collide, divergent , where plates separate, and transform motion, where plates simply slide past each other.
What is sea floor spreading and what causes it?
Seafloor spreading occurs at divergent plate boundaries. As tectonic plates slowly move away from each other, heat from the mantle’s convection currents makes the crust more plastic and less dense. The less-dense material rises, often forming a mountain or elevated area of the seafloor. Eventually, the crust cracks.
What are the 4 steps of seafloor spreading?
- Magma comes out of the rift valley.
- Magma cools to rock and hardens.
- Rock is pushed away as new rock is formed at MOR.
- Oceanic crust and continental crust meet at the trench.
- Oceanic crust bends down under the continental crust.
- Gravity pulls rock towards mantle.
- Rock melts to mantle.
Which is the first step in seafloor spreading?
1. A long crack in the oceanic crust forms at a mid ocean ridge . 2. Molten material rises and erupts along the ridge.
What is the first step in seafloor spreading process?
As the seafloor spreading occurs, the continents move. How does oceanic crust move along mid-ocean ridges? Which is the first step in the seafloor spreading process? A crack forms in oceanic crust.
What is the importance of seafloor spreading?
Significance. Seafloor spreading helps explain continental drift in the theory of plate tectonics . When oceanic plates diverge, tensional stress causes fractures to occur in the lithosphere.
What are the two evidence of seafloor spreading?
Abundant evidence supports the major contentions of the seafloor-spreading theory. First, samples of the deep ocean floor show that basaltic oceanic crust and overlying sediment become progressively younger as the mid-ocean ridge is approached, and the sediment cover is thinner near the ridge .
What are the features of seafloor?
Features of the ocean include the continental shelf, slope, and rise . The ocean floor is called the abyssal plain. Below the ocean floor, there are a few small deeper areas called ocean trenches. Features rising up from the ocean floor include seamounts, volcanic islands and the mid-oceanic ridges and rises.
Where is active seafloor spreading occurring today?
Where is active sea floor spreading occurring today? Seafloor spreading is the movement of old rock that is being pushed by the new young oceanic crust. This would be a divergent since the plates are separating from each other. Active seafloor spreading is occurring at mid-ocean ridges .
Why do tectonic plates move?
The heat from radioactive processes within the planet’s interior causes the plates to move, sometimes toward and sometimes away from each other. This movement is called plate motion, or tectonic shift.
Why is Earth not growing in spite of seafloor spreading?
New crust is continually being pushed away from divergent boundaries (where sea-floor spreading occurs), increasing Earth’s surface. But the Earth isn’t getting any bigger . ... Deep below the Earth’s surface, subduction causes partial melting of both the ocean crust and mantle as they slide past one another.
