Plate Tectonic Theory In this presentation you will

Plate Tectonic Theory In this presentation you will: n explore historical development that supports plate tectonic theory Next >

Pangaea (1 of 1) Continents fit together like puzzle pieces. Pangaea is a large supercontinent that split into several pieces, These pieces became Earth's current continents. Next >

Alfred Wegener and Theory of Continental Drift (1 of 1) In 1912 a scientist named Alfred Wegener theorized that the continents had once been joined together and drifted over millions of years. This was called theory of Continental Drift Unfortunately he had no scientific proof, and could not explain what moved the continents Next >

Evidence of Continental Drift (1 of 1) Fossils of the same species of plants and animals were found across different continents. This supported Wegener’s theory that the continents had once been joined together. Next >

Plate Tectonic Theory (1 of 1) Continental drift was disputed by scientists for many years. However, as more evidence was found, it became universally accepted. With the discovery of fossils and seafloor spreading scientists came up with the Theory of plate tectonics Next >

Tectonic Plates (1 of 1) The outer layer of the Earth is broken up into a different tectonic plates and fit together like a puzzle. Juan De Fuca plate North American plate Pacific plate Cocos plate Eurasian plate Caribbean plate Arabian plate Nazca South plate American plate Scotia plate African plate Indian plate North American plate Philippine plate Pacific plate Indo-Australian plate Antarctic plate The tectonic plates are constantly moving at a very slow speed, and this movement can change the Earth’s surface. Next >

Lithospheric and Asthenosphere Plates (1 of 1) The plates of the outer layer of Earth made of the crust, and the solid part of the upper mantle are the called the Lithospheric Plates. The Asthenosphere is a semi liquid that the lithosphere floats on. It allows the lithosphere and plates to move Next >

What Causes Plate Motion? (1 of 2) Imagine you are cooking an egg in a pot of water. As the water is heated and the temperature increases, the egg floating at the surface begins to move. The hot particles rise to the surface, when they cool they sink back down. This cycle is called a convection current. The movement in the hot water causes the egg to move. Next >

What Causes Plate Motion? (2 of 2) Convection currents within the Earth’s mantle cause the plates floating above to move. Plates Mantle This convection takes millions of years. Next >

Plate Movement (1 of 2) The plates collide, pull apart or scrape against each other depending on their relative directions. The effects of the plate motion can be seen at the edges (boundaries) of the plates. Next >

Plate Movement (2 of 2) Plate movement can cause volcanic eruptions, earthquakes, and mountain formation. Next >

Types of Plate Boundary (1 of 1) There are three types of boundaries between plates: n Convergent – The boundary between two plates that are moving towards each other. n Divergent – The boundary between two plates that are pulling apart. n Transform – The boundary between two plates that are sliding past each other horizontally. Next >

Convergent Boundaries (1 of 1) When two plates collide, one plate is forced below the other. Crust is destroyed On the ocean floor, a trench is formed. Trenches are narrow, deep cuts. Trench Creates: volcanoes, folded mountains, Ocean trenches, subduction zones, Next >

Types on Convergent boundaries (1 of 1) Oceanic – Continental An oceanic plate slides under (subduction) a continental plate. The continental plate is pushed up and a volcano is created Oceanic – Oceanic Two oceanic plates converge and the oldest crust is pushed under (subduction). Oceanic trench , under water volcanoes, and volcanic islands are formed. Continental – Continental Two continents converge and are pushed up. High mountains are created

Oceanic Trenches (No notes on this page) Probably the most famous trench (for being so deep) is the Mariana trench in the Pacific Ocean. Its deepest point is about 11, 000 m (36, 000 ft) below sea level. That’s 2, 000 m deeper than Mount Everest is tall! Next >

Divergent Boundaries (1 of 1) Plates pull apart and cause cracks to appear on the surface. Magma escapes through the cracks onto the surface. The magma then hardens to form new rock. Creates: Mid ocean ridges, rift valleys, new crust, sea floor spreading Magma hardens to form rock Magma escapes Next >

Transform Boundaries (1 of 1) Or Sliding boundaries two plates slide past each other Lots of stress is put on the rocks causing them to deform and form a crack or fault. Creates: Earthquakes, deforms crust San Andreas Fault, California San Francisco earthquake 1906 Next >