Plate Tectonics Mrs. Mia Conlon Marine Science

History Alfred Wegener hypothesized all the lands were a single protocontinent called Pangaea Pangaea means “all lands” or “all Earth” Continental shelves provide the best fit Couldn’t provide an excepted mechanism to support until after death in the 1960’s

Continental Drift The theory that the continents move or “drift” relative to each other Wegener was the first to use the term even though the theory had been around since the 19 th century Supported by geologic and fossil evidence Has been encompassed into plate tectonics

Plate Tectonics DEFINITION - scientific theory that describes the large-scale motion of Earth's lithosphere The rigid lithosphere has plates (oceanic & continental crust) that move above the fluid asthenosphere. The movement is caused by convection currents within the asthenosphere. Material rises as it is heated and falls as it cools creating a circular pattern and motion.

Supported by Geologic evidence – matching striations at continental edges Fossil evidence – matching species along continental edge areas Paleomagnetism – magnetite and particle orientation Sea Floor Spreading - Theory of new crust being created at ridge, pushed away, and returning underneath plate at trenches. Proposed by Hess in 1960’s Heat flow

Divergent Boundary

Terms for Divergent Boundary Lithosphere - the crust plus the rigid, upper mantle. Lower Mantle (semi-rigid) - the deepest parts of the mantle, just above the core. Magma - molten rock withing the Earth's mantle. In seafloor spreading, magma moves from the asthenosphere to the crust. Ocean - large bodies of water sitting atop oceanic crust. Oceanic Crust - thin parts of the Earth's crust located under the oceans. Oceanic Ridge - newly-formed region of the oceanic crust. Upper Mantle (rigid) - the uppermost part of the mantle, part of the lithosphere. Asthenosphere = Upper Mantle (flowing) - the lower part of the upper mantle that exhibits plastic (flowing) properties. It is located below the lithosphere (the crust and upper mantle).

Divergent Boundary characteristics Plates move apart Creates new sea floor Mid-ocean ridges

Convergent Boundary

Terms for Convergent Boundary Asthenosphere = Upper Mantle (flowing) - the lower part of the upper mantle that exhibits plastic (flowing) properties. It is located below the lithosphere (the crust and upper mantle). Continental Crust - thick parts of the Earth's crust, not located under the oceans. Lithosphere - the crust plus the rigid, upper mantle. Lower Mantle (semi-rigid) - the deepest parts of the mantle, just above the core. Magma - molten rock withing the Earth's mantle. In seafloor spreading, magma moves from the asthenosphere to the crust. Ocean - large bodies of water sitting atop oceanic crust. Oceanic Crust - thin parts of the Earth's crust located under the oceans. Subduction Zone - the area in which one part of the Earth's crust (a plate) is pushed underneath another plate as the two plates collide. Upper Mantle (rigid) - the uppermost part of the mantle, part of the lithosphere. Volcanos - a place on the Earth's surface where molten rock, gases and pyroclastic debris erupt through the earth's crust.

Convergent Boundary Characteristics Plates move towards each other Old sea floor is destroyed trenches

Transform Boundary

Transform Boundary Characteristics Plates move past each other No destruction or creation of crust Faults are formed Numerous types of faults