Quick Answer: What Causes Seafloor Spreading And Continental Drift?

What was the first evidence of continental drift?

The first truly detailed and comprehensive theory of continental drift was proposed in 1912 by Alfred Wegener, a German meteorologist.

Bringing together a large mass of geologic and paleontological data, Wegener postulated that throughout most of geologic time there was only one continent, which he called Pangea..

Which natural process is responsible for Ridge push?

Seafloor spreadingSeafloor spreading is the natural process responsible for ridge push.

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 causes 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.

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.

What are the 4 evidence of continental drift?

The evidence for continental drift included the fit of the continents; the distribution of ancient fossils, rocks, and mountain ranges; and the locations of ancient climatic zones.

What was Harry Hess’s theory of seafloor spreading?

Hess envisaged that oceans grew from their centres, with molten material (basalt) oozing up from the Earth’s mantle along the mid ocean ridges. This created new seafloor which then spread away from the ridge in both directions.

Is the earth’s crust solid?

Earth has three layers: the crust, the mantle, and the core. The crust is made of solid rocks and minerals. Beneath the crust is the mantle, which is also mostly solid rocks and minerals, but punctuated by malleable areas of semi-solid magma. At the center of the Earth is a hot, dense metal core.

What are 3 pieces of evidence for Pangea?

Alfred Wegener, in the first three decades of this century, and DuToit in the 1920s and 1930s gathered evidence that the continents had moved. They based their idea of continental drift on several lines of evidence: fit of the continents, paleoclimate indicators, truncated geologic features, and fossils.

What causes 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.

What causes the seafloor to spread and continents to drift?

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 the 4 steps of seafloor spreading?

Terms in this set (7)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 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.

What causes continental drift?

Wegener suggested that perhaps the rotation of the Earth caused the continents to shift towards and apart from each other. … 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.

What is the history of the theory of seafloor spreading?

Seafloor spreading is the mechanism by which new seafloor lithosphere is constantly being created at mid-ocean ridges. This theory, introduced by Harry Hess, was proven as patterns of magnetic field polarity preserved in seafloor basalt and by age dating of the rocks.

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 are 6 pieces of evidence that support continental drift?

What are six pieces of evidence for the continental drift theory? Reptile Fossils- dinosaurs couldn’t have swam across a vast ocean. Plant Fossils- all these regions were once connected and had similar climates. Tropical plants found in Arctic- tropical plants can’t grow in cold climates.

Which is the first step in the seafloor spreading process?

A crack forms in oceanic crust. Molten rock rises up through oceanic crust. Molten rock solidifies at the center of the ridge.

What is 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 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.

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.