Plate tectonics: The theory that explains how large pieces of the lithosphere, called plates, move and change shape. The Earth’s crust, together with the upper region of the mantle, consists of huge slabs of rock called Plates tectonics. These fit together rather like the segments on the shell of a tortoise.
Continental Drift: The hypothesis that states that the continents once formed a single landmass, broke up, drifted to their present locations, Continental Drift is the movement of the Earth's continents relative to each other by appearing to drift across the ocean bed.
Pangaea: The super continent that formed 300 million years ago and that began to break up 250 million years ago. The single global ocean which surrounded Pangaea is accordingly named pathalassa.
Asthenosphere: The solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonics plates to move on top of it. A thin semifluid layer of the earth (100-200 km thick), below the outer rigid lithosphere, forming part of the mantle and thought to be able to flow vertically and horizontally, enabling sections of lithosphere to subside, rise, and undergo lateral movement.
Lithosphere: the solid, outer layer of Earth that consists of the crust ant the rigid upper part of the mantle. outermost shell of a rocky planet defined on the basis of the mechanical properties.
Mid-Oceanic ridge: A long, undersea mountain chain that has a steep, narrow valley at its center, that forms as magma rises from the asthenosphere, and that creates new oceanic lithosphere (sea floor) as tectonics plates move apart.
Rift valleys: The process by which Earth's crust breaks apart; can occur within continental crust or oceanic. A rift valley is a linear-shaped lowland between several highlands or mountain ranges created by the action of a geologic rift or fault. A rift valley is formed on a divergent plate boundary, a crustal extension, a spreading apart of the surface, which is subsequently further deepened by the forces of erosion
Subduction: The subduction zone is the place where two lithospheric plates come together, one riding over the other. Most volcanoes on land occur parallel to and inland from the boundary between the two plates.