What are the 4 steps of seafloor spreading?

Evidence for Sea-Floor 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.

Evidence for Sea-Floor 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.

Similarly, what is the first step of seafloor spreading quizlet? 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.

Beside this, what is the concept 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?

Home. As defined by the textbook, Seafloor Spreading is the mechanism that operates along the oceanic ridge system to create new seafloors. The average speed of seafloor spreading is approximately 5 centimeters a year.

What are the effects of seafloor spreading?

Mid-ocean ridges and seafloor spreading can also influence sea levels. As oceanic crust moves away from the shallow mid-ocean ridges, it cools and sinks as it becomes more dense. This increases the volume of the ocean basin and decreases the sea level.

What are the strongest evidence for 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 is the theory of continental drift?

Continental drift was a theory that explained how continents shift position on Earth’s surface. Set forth in 1912 by Alfred Wegener, a geophysicist and meteorologist, continental drift also explained why look-alike animal and plant fossils, and similar rock formations, are found on different continents.

Why is seafloor spreading important?

Significance. Seafloor spreading helps explain continental drift in the theory of plate tectonics. The motivating force for seafloor spreading ridges is tectonic plate slab pull at subduction zones, rather than magma pressure, although there is typically significant magma activity at spreading ridges.

What evidence exists for seafloor spreading?

Earthquake zones [175 k] The recognition of such a connection helped confirm the seafloor-spreading hypothesis by pin-pointing the zones where Hess had predicted oceanic crust is being generated (along the ridges) and the zones where oceanic lithosphere sinks back into the mantle (beneath the trenches).

What did Glomar Challenger do to confirm?

Purpose. Glomar Challenger was made to help Harry Hess with the theory of Seafloor Spreading by taking rock samples confirming that the farther from the Mid-ocean ridge, the older the rock was.

What are the two tectonic plates called?

Tectonic plates are pieces of Earth’s crust and uppermost mantle, together referred to as the lithosphere. The plates are around 100 km (62 mi) thick and consist of two principal types of material: oceanic crust (also called sima from silicon and magnesium) and continental crust (sial from silicon and aluminium).

What are tectonic plates made of?

A tectonic plate (also called lithospheric plate) is a massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere. Plate size can vary greatly, from a few hundred to thousands of kilometers across; the Pacific and Antarctic Plates are among the largest.

What ocean is the smallest?

Arctic Ocean

Where is the seafloor the oldest?

The next oldest seafloor is found at the margins of the north Atlantic Ocean and the northwestern Pacific Ocean, as far as possible from the mid-ocean ridges where they were created. These parts of the seafloor are about 200 million years old. Age of the oceanic crust.

Where does subduction occur?

Subduction is a geological process that takes place at convergent boundaries of tectonic plates where one plate moves under another and is forced to sink due to high gravitational potential energy into the mantle. Regions where this process occurs are known as subduction zones.

What is the theory of plate tectonics?

From the deepest ocean trench to the tallest mountain, plate tectonics explains the features and movement of Earth’s surface in the present and the past. Plate tectonics is the theory that Earth’s outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core.

Where do divergent boundaries occur?

Most active divergent plate boundaries occur between oceanic plates and exist as mid-oceanic ridges. Divergent boundaries also form volcanic islands, which occur when the plates move apart to produce gaps that molten lava rises to fill.

When did the continents separate?

175 million years ago