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.
What are two pieces of evidence for seafloor spreading?
Several types of evidence from the oceans supported Hess’s theory of sea-floor spreading- evidence from molten material, magnetic stripes, and drilling samples . This evidence also led sci- entists to look again at Wegener’s theory of continental drift.
What causes seafloor spreading quizlet?
During sea-floor spreading, magma erupts along a mid-ocean ridge to form new oceanic lithosphere. The floor then moves away from the ridge, often toward a trench at the edge of the ocean basin. ... The pattern shows that ocean floor forms along mid-ocean ridges and then moves away from the ridge.
What evidence is there that sea-floor is spreading apart?
The seafloor drilling system led to the evidence that supports the seafloor-spreading hypothesis. The samples obtained from the seafloor drill reveals that the rocks away from the mid-oceanic ridge were relatively older than the rocks near to it.
Where does seafloor spreading start?
Sea floor spreading begins at the mid ocean ridge which forms a crack in the oceanic crust. This allows molten material to rise and form new rock. At the same time older rock move outwards and onto the sides of the ridge. the process by which ocean floor sinks beneath a deep ocean trench and back into the mantle.
What are three features of the ocean floor?
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.
Is sea floor spreading a fast or slow process?
It spreads about 6-16 centimeters (3-6 inches) every year. There is not an ocean trench at the East Pacific Rise, because the seafloor spreading is too rapid for one to develop !
Is the Earth’s diameter getting bigger because 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 .
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 .
What are three kinds of evidence of the ocean floor spreading?
a. The pieces of evidence gathered for sea-floor spreading include the evidence from molten material, magnetic stripes, and drilling samples .
What happens when the seafloor spreads?
Sea-floor spreading is what happens at the mid-oceanic ridge where a divergent boundary is causing two plates to move away from one another resulting in spreading of the sea floor . As the plates move apart, new material wells up and cools onto the edge of the plates.
What happens when a piece of crust is subducted?
Where two tectonic plates meet at a subduction zone, one bends and slides underneath the other, curving down into the mantle . (The mantle is the hotter layer under the crust.) ... At a subduction zone, the oceanic crust usually sinks into the mantle beneath lighter continental crust.
Do spreading centers move?
Spreading centers occur where two plates are moving away from each other , and deep cracks are opened through the crust. This lengthening of the crust allows magma from the upper mantle to rise to the surface and cool, commonly forming basalt. An excellent example is the Mid-Atlantic Ridge.
What does the crust record as it cools?
How to form magnetic striping: new oceanic crust forms continuously at the mid-ocean ridges. While it cools down, it records the magnetic field during its formation. The two parts of the oceanic plate are pulled apart, and magnetic stripes become older as they move away from the mid-ocean ridge.
What boundary destroys the seafloor?
You are correct that the seafloor is destroyed at subduction zones , but it is simultaneously being created at mid-ocean ridges. see figure 1 . Figure 1: Seafloor spreading at a mid-ocean ridge(where new crust is being created) and it’s destruction at a subduction zone.
What are 4 features of the ocean floor?
Features of the ocean floor include the continental shelf and slope, abyssal plain, trenches, seamounts, and the mid-ocean ridge . The ocean floor is rich in resources. Living things on the ocean floor are used for food or medicines.
