What is seafloor spreading and plate tectonics? How does seafloor spreading and plate tectonics connect previous theories of the movement of continents?

Answer 1

· Seafloor spreading involves the creation of new crust and the destruction of old crust. Spreading centers occur where there is formation of new crust rising from the asthenosphere. The ocean floor is thinner in these areas. As the crust cools and moves away from the centers it becomes cool and more dense.
· The discovery of subduction zones enhanced the credibility of the seafloor spreading and plate tectonics theories. Subduction zones are areas where crust plunges back down into the mantle.
· Plate tectonics involves the movement of different lithospheric plates across the asthenosphere. These plates can be outlined by volcanic activities and mountain ranges. They move by two forces. When crust forms at the spreading centers it then slides off the raised ridges. The second force occurs when the crust is pulled downward into the mantle by the cool, dense leading edge.
· Seafloor spreading and plate tectonics built upon Alfred Wegener's previous theory of continental drift by explaining the driving force of the movement of the continents.