Subduction: the sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate.
Example: The Mariannas Trench in the Pacific Ocean
Example: The Mariannas Trench in the Pacific Ocean
Rift valleys: a large elongated depression with steep walls formed by the downward displacement of a block of the earth's surface between nearly parallel faults or fault systems.
Example: Kenya has a rift valley.
Example: Kenya has a rift valley.
Mid-ocean ridge: A series of mountain ranges on the ocean floor, more than 84,000 kilometers (52,000 miles) in length, extending through the North and South Atlantic, the Indian Ocean, and the South Pacific. According to the plate tectonics theory, volcanic rock is added to the sea floor as the mid-ocean ridge spreads apart.
Example: Pacific Antarctic Ridge
Example: Pacific Antarctic Ridge
Lithosphere: the rigid outer part of the earth, consisting of the crust and upper mantle.
Example: The crust and the upper portion of the mantle form the lithosphere.
Example: The crust and the upper portion of the mantle form the lithosphere.
Asthenosphere: the upper layer of the earth's mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.
Example: The asthenosphere lies beneath the lithosphere and is a zone of earths mantle.
Example: The asthenosphere lies beneath the lithosphere and is a zone of earths mantle.
Paganea: A hypothetical supercontinent that included all the landmasses of the earth
before the Triassic Period. Pangaea broke apart during the Triassic and Jurassic
Periods, separating into Laurasia and Gondwanaland.
before the Triassic Period. Pangaea broke apart during the Triassic and Jurassic
Periods, separating into Laurasia and Gondwanaland.
Continental Drift: the gradual movement of the continents across the earth's surface through geological time.
Example: Australia moving 2cm North per year.
Example: Australia moving 2cm North per year.
Plate Tectonics: theory explaining the structure of earth's crust & many associated phenomena as resulting from interaction of rigid lithospheric plates that move slowly over the underlying mantle.
Example: The San Andreas Fault
Example: The San Andreas Fault