Quick Answer: What Are The 4 Steps Of Seafloor Spreading?

What is the first step of seafloor spreading quizlet?


A long crack in the oceanic crust forms at a mid ocean ridge.


Molten material rises and erupts along the ridge..

How do we know seafloor spreading is happening?

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.

How do the continents move?

Today, we know that the continents rest on massive slabs of rock called tectonic plates. The plates are always moving and interacting in a process called plate tectonics. … As the seafloor grows wider, the continents on opposite sides of the ridge move away from each other.

Where does slab pull occur?

The process of a tectonic plate descending into the mantle is termed subduction. Slab pull occurs when an oceanic plate subducts into the underlying mantle. Subduction zones are just one type of convergent boundary where two tectonic plates are colliding.

What are the 4 evidences of seafloor spreading?

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.

What causes the plates to move?

The plates can be thought of like pieces of a cracked shell that rest on the hot, molten rock of Earth’s mantle and fit snugly against one another. The heat from radioactive processes within the planet’s interior causes the plates to move, sometimes toward and sometimes away from each other.

What 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.

What is the root cause of the magnetic stripes that occur on the ocean floor?

Rising magma assumes the polarity of Earth’s geomagnetic field before it solidifies into oceanic crust. … When Earth’s geomagnetic field undergoes a reversal, the change in polarity is recorded in the magma, which contributes to the alternating pattern of magnetic striping on the seafloor.

What is the average speed of seafloor spreading?

approximately 5 centimeters a yearThe average speed of seafloor spreading is approximately 5 centimeters a year. This growth rate can be compared to the growth rate of human fingernails (Krupicka). The global ridge system consists of oceanic ridges. Seafloor spreading occurs at these elevated oceanic ridges and has high heat flow and volcanism.

What is the first step in seafloor spreading?

Sea-Floor Spreading begins at a mid-ocean ridge, which forms along a crack in the oceanic crust. along the ridge, molten material that forms several kilometers beneath the surface rises and erupts. at the same time, older rock moves outward on both sides of the ridge.

Who discovered seafloor spreading?

Harry HessHarry Hess was a geologist and Navy submarine commander during World War II. Part of his mission had been to study the deepest parts of the ocean floor. In 1946 he had discovered that hundreds of flat-topped mountains, perhaps sunken islands, shape the Pacific floor.

What is the process of seafloor spreading?

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.

Where is active seafloor spreading 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.

Where does seafloor spreading occur quizlet?

Where does seafloor spreading occur? This process occurs along divergent plate boundaries at areas called mid-ocean ridges.

Why is seafloor spreading important?

Significance. Seafloor spreading helps explain continental drift in the theory of plate tectonics. … At a spreading center, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed. Hydrothermal vents are common at spreading centers.

In which direction does the ocean floor move in the process of seafloor spreading?

What is the process of sea-floor spreading? 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 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. As a result, the ocean floors move like conveyor belts, carrying the continents along with them. … an undersea mountain chain where new ocean floor is produced.