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

Earth’s Layers

http://homepage.usask.ca/~src594/thestructureofearth.jpg

EGGS-celent!

Crust

Mantle

Inner Core

Outer Core

http://earthquake.usgs.gov/learning/teachers/EarthEgg.pdf

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

http://stloe.most.go.th/html/lo_index/LOcanada1/102/images/L02_3.jpg

Earth’s Major Plates

http://www.enchantedlearning.com/egifs/Earthsplates.GIF

Plate BoundariesTransform 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.

http://www.biog1105-1106.org/demos/106/unit08/media/san-andreas-fault.jpg\

http://stloe.most.go.th/html/lo_index/LOcanada4/403/images/4_1.jpg

Plate BoundariesDivergent (Constructive)Oceanic plate & Oceanic plate

http://stloe.most.go.th/html/lo_index/LOcanada4/403/images/1_1.jpg

-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 BoundariesDivergent Continental plate & Continental plate

http://stloe.most.go.th/html/lo_index/LOcanada4/403/images/1_2.jpg

-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. http://taos-telecommunity.org/EPOW/EPOW-Archive/archi

ve_2008/EPOW-081027_files/P1180531%20Rift%20Valley%20escarpments%20L&R_big.jpg

Plate BoundariesConvergent (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.

http://stloe.most.go.th/html/lo_index/LOcanada4/403/images/3_1.jpg

Plate BoundariesConvergentOceanic 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

http://www.sema.go.th/files/Content/science/k4/0035/F01/images/Th/03/3_2.jpg

http://img2.travelblog.org/Photos/841/2784/f/9037-Ushuaia-bay-with-the-southernmost-tail-of-the-Andes-in-the-background-0.jpg

Ushuaia Bay with the southernmost tip of

Andes in the background in

Argentina

Plate BoundariesConvergentOceanic 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

http://stloe.most.go.th/html/lo_index/LOcanada4/403/images/3_3.jpg

http://www.cartage.org.lb/en/themes/sciences/earthscience/geology/volcanoes/currentvolcanoes/metis2.gif

Metis Volcano is one of the Tonga Islands

Plate BoundariesConvergentContinental plate & continental plate

http://stloe.most.go.th/html/lo_index/LOcanada4/403/images/3_4.jpg

-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.

http://help.berberber.com/members/sajalarora/albums/natural-beauty-india/2026-himalayas.jpg

Activity time!

Snack tectonics

Now you can EAT your snacks!

Questions?

Resources

• http://stloe.most.go.th/html/lo_index/LOcanada4/403/html/1_en.htm

• http://en.wikipedia.org/wiki/Tectonic_plate#Divergent_.28constructive.29_boundaries