By: Kat Kenney, Jeff Hicks, and Carissa Blanco Chapter 10 Section 3 By: Kat Kenney, Jeff Hicks, and Carissa Blanco

Plate Tectonics Plate tectonics is the theory that Earth’s crust and upper mantle are broken into plates that float and move around on a plastic like layer of the mantle.

Plates are sections of Earth’s crust and upper mantle.

Lithosphere The lithosphere is the rigid layer of Earth that is about 100 km thick. It is made of the crust and a part of the upper mantle.

Asthenosphere The asthenosphere is the plastic like layer of Earth on which the lithospheric plates float and move around.

Convection Current A convection current is a current in earth’s mantle that transfers heat in Earth's interior and is the driving force for plate tectonics. It is also known as the cycle of heating, rising, and cooling.

When continental plates pull apart, they can form rift valleys.

Subduction Where oceanic and continental plates collide, the oceanic plate plunges beneath the less dense continental plate. As the plate descends, molten rock forms and rises towards the surface, forming volcanoes.

Seafloor Spreading Hess’s theory that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge.

Continental Collision Where two continental plates collide, they push up the crust to form mountain ranges such as the Himalaya.

Plate Boundaries One type of plate boundary is a convergent boundary, where plates move together. Another type of plate boundary is a divergent boundary, where plates pull apart. Finally, there is a transform boundary where plates slide past each other.

Volcanoes A volcano can form at a subduction zone. When the oceanic plate plunges beneath the continental plate, it melts. The magma rises into the continental plate and forms volcanoes.