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What 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. The less-dense material rises, often forming a mountain or elevated area of the seafloor. Eventually, the crust cracks.Jun 8, 2015

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.

How seafloor spreading occurs in the mid-ocean ridge?

Seafloor spreading is the process by which new oceanic lithosphere forms at mid-ocean ridges. As tectonic plates move away from each other, magma rises from Earth’s interior. It then cools and solidifies in the center of the ridge. The rising magma pushes up between the plates and drives them further apart.

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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 is a fact about seafloor spreading?

Seafloor spreading happens at the bottom of an ocean as tectonic plates move apart. … It forms new crust as the plates move away from each other. The new crust then slowly moves away from the ridge. It is a place of earthquakes and volcanos.

What causes tectonic plates to 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 causes the seafloor to spread apart at mid ocean ridges quizlet?

What causes the sea floor to spread apart at mid-ocean ranges? Hot magma rises through the boundaries at the mid-ocean ranges, creating new rock as it cools and pushing the plates apart.

What causes the mid-ocean ridges to form?

The mid-ocean ridge is a continuous range of undersea volcanic mountains that encircles the globe almost entirely underwater. … It formed and evolves as a result of spreading in Earth’s lithosphere—the crust and upper mantle—at the divergent boundaries between tectonic plates.

Who proved that the seafloor is spreading?

Harry H. Hess

The seafloor spreading hypothesis was proposed by the American geophysicist Harry H. Hess in 1960.

What causes new material to form at a mid-ocean ridge on the ocean floor?

A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. This uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.

How did Harry Hess prove seafloor spreading?

Hess discovered that the oceans were shallower in the middle and identified the presence of Mid Ocean Ridges, raised above the surrounding generally flat sea floor (abyssal plain) by as much as 1.5 km. … This created new seafloor which then spread away from the ridge in both directions.

What supports the theory 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 strongest evidence for seafloor spreading?

Evidence of Sea Floor Spreading

1. Molten material. Hess’s discovery on the warmer temperature near the mid-Atlantic ridge when he began the ocean mapping, led to his evidence about the molten material underneath the ocean. …
2. Seafloor drill. …
3. Radiometric age dating and fossil ages. …
4. Magnetic stripes.

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What is the importance of seafloor spreading in understanding the origin of the plate?

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.

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.

Which is one piece of evidence of seafloor spreading?

One piece of evidence of seafloor spreading is a mid-ocean ridge. Explanation: The Mid-Atlantic Ridge is a mountain system formed by plate tectonics on the seafloor.

What are three causes of plate movement?

Mantle dynamics, gravity, and Earth’s rotation taken altogether causes the plate movements. However, convectional currents are the general thought for the motion.

What are the two main factors that cause the movement of tectonic plates?

Heat and gravity are fundamental to the process

The energy source for plate tectonics is Earth’s internal heat while the forces moving the plates are the “ridge push” and “slab pull” gravity forces. It was once thought that mantle convection could drive plate motions.

What force causes most of the plate movement?

Research has shown that the major driving force for most plate movement is slab pull, because the plates with more of their edges being subducted are the faster-moving ones. However, ridge push is also presented in recent research to be a force that drives the movement of plates.

What causes the movement of tectonics plate quizlet?

convection currents are a process in which the materials inside the mantle heat up and rise to the surface whilst the cooler liquid sinks; as it sinks it then heats up and rises again. This continuous cycle is established: hot liquid rising, cold liquid descending. These currents cause the tectonic plates to move.

What causes magnetic stripes on the seafloor quizlet?

Why does the rock of the ocean floor have a pattern of magnetic stripes? The rock of the ocean floor contains iron. As molten material cooled and hardenend, the iron bits inside lined up in the direction of Earth’s magnetic poles, creating a pattern of magnetized stripes.

What causes continents to move Hess?

Photo: Harry Hess argues that the continents had once been one, and have drifted apart. … After much thought, he proposed in 1960 that the movement of the continents was a result of sea-floor spreading. In 1962, he added a geologic mechanism to account for Wegener’s moving continents.

What is the major evidence that sea floor spreading creates new lithosphere explain your answer?

The record of magnetic reversals is carried away from each side of the spreading center of a mid-ocean ridge, showing that the molten rock is creating new lithosphere.

What causes a ridge to form along a divergent plate boundary?

When two plates are moving away from each other, we call this a divergent plate boundary. Along these boundaries, magma rises from deep within the Earth and erupts to form new crust on the lithosphere. Most divergent plate boundaries are underwater and form submarine mountain ranges called oceanic spreading ridges.

Why does ocean crust far from a mid-ocean ridge subside?

As the sheets of oceanic crust move away from the mid-ocean ridge, the rock is cooled and thus becomes heavier. After about 200 million years, the cooled lithospheric plate has become heavier than the asthenosphere that it rides over, and it sinks, thereby producing a subduction zone.

What causes the lithosphere to crack and create a fissure?

According to the study, the early Earth’s outer shell, or lithosphere, heated up, which caused it to expand and crack. … But, according to Webb, the answer to Earth’s tectonic origins “lies in consideration of major heat-loss mechanisms that could have occurred during Earth’s early periods,” they said in a statement.

What is the first step in the seafloor spreading process?

1. A long crack in the oceanic crust forms at a mid ocean ridge. 2. Molten material rises and erupts along the ridge.

Which event causes the formation of trenches in Earth’s crust?

Trenches are formed by subduction, a geophysical process in which two or more of Earth’s tectonic plates converge and the older, denser plate is pushed beneath the lighter plate and deep into the mantle, causing the seafloor and outermost crust (the lithosphere) to bend and form a steep, V-shaped depression.

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What is 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. As a result, the ocean floors move like conveyor belts, carrying the continents along with them.

What is the primary reason for the elevated position of the oceanic ridge system?

The primary reason for the elevated position of the ridge system is that newly created oceanic lithosphere is hot and therefore less dense than cooler rocks of the deep-ocean basin.

Seafloor Spreading