Q:

What is the theory of seafloor spreading?

A:

Quick Answer

Seafloor spreading is an oceanic process involving the formation of new oceanic crust through the solidification of basaltic magma at mid-ocean ridges. This process is a partial explanation for the process of Continental Drift.

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Full Answer

The magma that forms these new plates emerges when oceanic plates part from one another due to climatic or geological stresses. Convection currents in the relatively weak and flexible upper mantle of Earth's crust are the driving cause of these stresses.

Rifts have the following features:

  • Most rift systems are triple-armed, meaning three fissures form.
  • Rifts begin as domes created by rising heat and pressure in the Earth's mantle.
  • Three-armed rifts spread until one arm dies and the remaining two extend to the extent of the crust's plasticity.

Full developed rifts can split continental masses from one another and eventually develop into new oceanic basins which will in time form oceans. Arabia and Africa are in the process of splitting due to the formation of just such a rift, but they will not complete this process for millions of years.

Existing rifts on the ocean floor map out the progress of continental masses and sea floor during the millennia of Earth's existence. Africa's Western coast is home to just such a concluded rift. The Earth is constantly being reshaped by this process.

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Related Questions

  • Q:

    What is the evidence for sea floor spreading?

    A:

    Encyclopædia Britannica states that many pieces of evidence support the sea floor spreading theory of plate tectonics, including increased heat flow along mid-ocean ridges, geomagnetic anomalies near ocean ridges, thickness of marine sediments and age of sediments. Sea floor spreading was first proposed by geophysicist Harry Hess in 1960 after reviewing submarine data. The theory is the basis for modern plate tectonics that states plates in the Earth's crust move.

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  • Q:

    How can plates move apart at the mid-ocean ridges and not leave a deep gap in the lithosphere?

    A:

    According to the National Oceanographic and Atmospheric Administration, the reason the divergent plate boundaries at mid-ocean ridges don't result in gaps in the Earth's crust is that when the plates move apart, they allow magma to well up from beneath and form new rock. At each of these ridges, new ocean floor is created constantly, filling in any potential gaps.

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    What is dolerite?

    A:

    A dolerite, also called a diabase, is an igneous rock, which means it was generated from the cooling and solidification of molten Earth material. It is also referred to as a volcanic rock.

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  • Q:

    What is a batholith?

    A:

    The term batholith refers to a large body of igneous rock that is formed below the surface of the earth because of the intrusion and solidification of magma. A batholith usually consists of coarse-grained rocks, such as granite or granodiorite.

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