The Definition of Tectonic Activity

Save

Plate tectonics is a geological theory that explains the phenomenon of continental drift. According to the theory, the Earth's crust is made up of continental and oceanic plates, which move across the surface of the planet, meeting at plate boundaries. Plate tectonics cause volcanic activity, mountain-building, ocean trench formation and earthquakes.

Continental Drift

  • The theory of continental drift was first proposed by Alfred Wegener in 1915. It had long been noted that continental coastlines appeared to fit together like giant puzzle pieces, most notably the west coast of Africa and the east coast of South America. Wegener hypothesized that a supercontinent, named Pangaea, existed 200 million years ago; this supercontinent subsequently broke apart in to several continental pieces. Since Wegener's hypothesis, substantial fossil and geological evidence has been compiled to validate continental drift theory.

Lithosphere and Asthenosphere

  • Continental drift is explained through the activity of tectonic plates. According to plate tectonics theory, the Earth's lithosphere, which is composed of the crust and a portion of the upper mantle, is broken into plates that float independently on top of the more liquid asthenosphere. There are eight major plates and many minor plates, which move relative to each other at plate boundaries. Plate boundaries are defined as convergent or colliding, divergent, or transform.

Plates and Plate Boundaries

  • Tectonic plates are divided into continental plates and oceanic plates. At convergent boundaries, subduction takes place as one plate slides beneath another, recycling the plate material into the mantle. With convergent oceanic plates, subduction always occurs. Ocean plates also always subduct below continental plates, often producing zones of volcanic activity and earthquake faults, such as occur along the West Coast of the United States. With colliding continental plates, neither may subduct, resulting in rising continental crust and the building of mountains and plateaus. The Himalayas are an example of mountains produced by the convergence or continental plates.

Sea Floor Spreading

  • As the lithosphere is recycled due to plate subduction, additional crust is created at divergent plate boundaries. Most divergent boundaries occur between oceanic plates, with the greatest amount of crust formation occurring at mid-oceanic ridges. At these boundaries, as the plates move away from each other, volcanic activity results in molten magma rising from the mantle to fill the open space. Activity can be pronounced at some divergent boundaries, resulting in volcanic islands, such as the Hawaiian Islands and other volcanic islands of the Pacific.

References

  • Photo Credit Jupiterimages/Photos.com/Getty Images
Promoted By Zergnet

Comments

You May Also Like

  • The Definition of Product Marketing Mix

    Products are the goods a business offers to consumers. The product marketing mix defines all the elements necessary to sell these goods...

  • Landforms Caused by Plate Tectonics

    The activity that occurs when two tectonic plates interact with each other can have a major impact on the landscape of the...

  • Definition of Tectonic Plates for Kids

    The theory of plate tectonics is a part of geology, which is the study of the earth and how it changes. Developed...

  • What Is a Tectonic Earthquake?

    Earthquakes occur when the planet's plates move against one another. This movement can create stress that causes the Earth's exterior shell, the...

  • Science Movement Activities

    Movement activities are an engaging and fun way to help students learn science. Increase participation, motivation and knowledge retention using these simple...

  • 10 Facts About Plate Tectonics

    The theory of plate tectonics is a widely accepted scientific theory that has wide application. Plate tectonics explain how mountains formed millions...

Related Searches

Check It Out

Can You Take Advantage Of Student Loan Forgiveness?

M
Is DIY in your DNA? Become part of our maker community.
Submit Your Work!