- Which area is likely the oldest crust?
- What is the average speed of seafloor spreading?
- Who proposed seafloor spreading?
- What is the first step of seafloor spreading?
- Why is seafloor spreading like a moving conveyor belt?
- Does the Earth get bigger because of seafloor spreading?
- How is paleomagnetism evidence of seafloor spreading?
- What is the source of magma for seafloor spreading?
- What are the steps of seafloor spreading?
- What is happening during seafloor spreading Where is the newer crust located?
- Where does seafloor spreading occur?
- How new crust is formed?
- What are the 4 evidence of continental drift?
- What is the main cause of seafloor spreading?
- What is the first step of seafloor spreading quizlet?
- What causes seafloor spreading quizlet?
- What is the evidence of seafloor spreading?
- What causes the tectonic plates to move?
Which area is likely the oldest crust?
Australia holds the oldest continental crust on Earth, researchers have confirmed, hills some 4.4 billion years old..
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.
Who proposed 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 first step of 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.
Why is seafloor spreading like a moving conveyor belt?
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.
Does the Earth get 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.
How is paleomagnetism evidence of seafloor spreading?
Magnetic reversals show up as bands of alternating polarity in the slowly spreading seafloor. … This explanation of magnetic striping by paleomagnetism convinced scientists that new oceanic crust was being continually formed at mid-oceanic ridges. Seafloor spreading was accepted as a reality.
What is the source of magma for seafloor spreading?
Sea-floor spreading — In the early 1960s, Princeton geologist Harry Hess proposed the hypothesis of sea-floor spreading, in which basaltic magma from the mantle rises to create new ocean floor at mid-ocean ridges.
What are the steps of seafloor spreading?
What are the steps in the process of sea floor 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.
What is happening during seafloor spreading Where is the newer crust located?
Explanation: New ocean crust is formed at the mid ocean ridges. The new crust is then pushed away from the ridge as newer crust comes to the surface. The ocean crust then spreads out enlarging the ocean.
Where does seafloor spreading occur?
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.
How new crust is formed?
Oceanic crust is constantly formed at mid-ocean ridges, where tectonic plates are tearing apart from each other. As magma that wells up from these rifts in Earth’s surface cools, it becomes young oceanic crust. The age and density of oceanic crust increases with distance from mid-ocean ridges.
What are the 4 evidence of continental drift?
They based their idea of continental drift on several lines of evidence: fit of the continents, paleoclimate indicators, truncated geologic features, and fossils.
What is the main cause of 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.
What is the first step of seafloor spreading quizlet?
1. A long crack in the oceanic crust forms at a mid ocean ridge. 2. Molten material rises and erupts along the ridge.
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. … These strips form a pattern that is the same on both sides of the mid-ocean ridge.
What is the evidence 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. This evidence led scientists to look again at Wegener’s hypothesis of continental drift.
What causes the tectonic plates to 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.