Presentation on theme: "PLATE TECTONICS Nafisa Skeie. What is plate tectonics? The build up of plates…?"— Presentation transcript:
PLATE TECTONICS Nafisa Skeie
What is plate tectonics? The build up of plates…?
Or is it the build up of food onto a plate…?
Geographically… Plate: Large, rigid slab of Earth’s solid rock + Tectonics: From the Greek root “to build” Plate Tectonics = The term which refers to how the Earth’s surface is built of plates
EGGS-celent! Crust Mantle Inner Core Outer Core
The Plates -Plates: large, rigid slab of Earth’s solid rock - are broken pieces from the lithosphere layer which is the crust of the Earth - ride on the hotter and weaker layer of the upper portion of the mantle called the asthenosphere - due to the various pressure in the upper mantle, the layer is plastic which allows the plates of the lithosphere to move around --> Theory of Plate Tectonics: Movements of the Earth’s plates
Earth’s Major Plates
Plate Boundaries Transform Fault (Sliding) -two plates grind past each other without the production or destruction of lithosphere -San Andreas Fault in California. -> Pacific plate is moving toward the northwest grinding past the North American plate which is traveling in the opposite direction. - Earthquakes are triggered along the fault boundaries org/demos/106/unit08/media/san-andreas-fault.jpg \
Plate Boundaries Divergent (Constructive) Oceanic plate & Oceanic plate -Plates move away from each other. -When two plates diverge, factures occur which are immediately filled with molten rock that wells up from the asthenosphere. This hot material cools and creates a new seafloor. -As a result, new oceanic crust (lithosphere) is continuously being created between the diverging plates. -The older crust moves away from the boundary, as it does so, it cools and contracts hence increasing in density and in thickness. -This is why the older and cooler oceanic crusts are deeper. Hyrdrothermal vents
Plate Boundaries Divergent Continental plate & Continental plate -Two continental plates moves apart from each other -The East African rift valleys represent the initial stage in the breakup of a continent. -Volcanic mountains such as Kilimanjaro and Mount Kenya are examples of the rift valleys that were formed by the associated faulting taking place. Archive/archive_2008/EPOW _files/P %20Rift%20Valley%20escarpmen ts%20L&R_big.jpg
Plate Boundaries Convergent (Subduction) -Plates move towards each other, resulting in subduction (consumption) of oceanic lithosphere into the mantle. -When two plates converge, the leading edge of one is bent downward, allowing it to descend beneath the other. -This region is called a subduction zone. -There are three types of convergent boundaries.
Plate Boundaries Convergent Oceanic plate & Continental plate -When a continental plate collides with an oceanic plate, the less dense continental plate will continue on its course while the denser oceanic plate will sink under the continental plate and into the asthenosphere. -As the descending plate increases in depth, the heat generated causes partial melting of the mantle creating magma which will accumulate beneath the overlying continental crust. -This can result in explosive volcanoes -Example is the Andes in South America in-the-background-0.jpg Ushuaia Bay with the southernmost tip of Andes in the background in Argentina
Plate Boundaries Convergent Oceanic plate & Oceanic plate -Two oceanic plate convergence, one will descend beneath the other. -Triggers volcanic activity …just like the oceanic-continental convergence, but the volcanoes forms on the ocean floor. -If the activity continues the volcanoes will emerge as islands in the ocean - Examples are the Mariana Islands in the western Pacific Ocean and the Tonga metis2.gif Metis Volcano is one of the Tonga Islands
Plate Boundaries Convergent Continental plate & continental plate -When two plates carrying continental crust converge it causes collision. -Since both plates are of low density and buoyant by the nature of the continental rock, neither will subduct. -Folding and deforming of sediments along the continental margins are then formed. -Example is the Himalayas which are a result of the Australian-Indian plate ramming into the Eurasian plate. mbers/sajalarora/albums/natu ral-beauty-india/2026- himalayas.jpg
Now you can EAT your snacks! Questions?
Resources ada4/403/html/1_en.htmhttp://stloe.most.go.th/html/lo_index/LOcan ada4/403/html/1_en.htm #Divergent_.28constructive.29_boundarie shttp://en.wikipedia.org/wiki/Tectonic_plate #Divergent_.28constructive.29_boundarie s