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 plate causes seafloor spreading?
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.
What type of plate movement is spreading?
The three main types of plate movements include: Divergent (Spreading):This is where two plates move away from each other. Molten rock from the mantle erupts along the opening, forming new crust. The earthquakes that occur along these zones, called spreading centers, are relatively small.
What causes the ocean floor to move?
Convection currents in the molten mantle cause the plates to slowly move about the Earth a few centimeters each year. Many ocean floor features are a result of the interactions that occur at the edges of these plates. The shifting plates may collide (converge), move away (diverge) or slide past (transform) each other.
What causes the seafloor to spread and continents to drift?
The surface of the Earth is made of interlocking tectonic plates. The tectonic plates are always moving in relation to each other. When two plates pull away from each other , the seafloor spreads along the boundary of the two plates.
What are the 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 causes the tectonic plates to continually move?
Tectonic shift is the movement of the plates that make up Earth’s crust. ... 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.
What are the 4 types of tectonic plate movement?
- Divergent: extensional; the plates move apart. Spreading ridges, basin-range.
- Convergent: compressional; plates move toward each other. Includes: Subduction zones and mountain building.
- Transform: shearing; plates slide past each other. Strike-slip motion.
What is the first step of 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 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.
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.
Do spreading centers move?
Spreading centers occur where two plates are moving away from each other , and deep cracks are opened through the crust. ... Subduction zones are associated with regions where two plates are moving towards each other, and the crust of the earth is shortened.
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.
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 the benefits of seafloor spreading?
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.
How has seafloor spreading caused the continents to move?
Seafloor spreading creates new oceanic crust at a mid-ocean ridge . ... On one side, the oceanic crust is subducted below the continental crust. On the other side, the two plates collide in a transform boundary, which is a horizontal type of movement. The latter is the closest we really come to continents drifting.
