7.3 Plate Tectonics. The Theory of Plate Tectonics Plate Tectonics – the theory that explains how large pieces of the Earth’s outermost layer called.

7.3 Plate Tectonics

The Theory of Plate Tectonics Plate Tectonics – the theory that explains

how large pieces of the Earth’s outermost layer called tectonic plates, move and change shape.

Tectonic Plate Boundaries

Boundary – a place where tectonic plates touch.

There are three different types of boundaries: Convergent Divergent Transform

Convergent Boundaries

Convergent Boundary – the boundary formed by the collision of two lithospheric plates.

There are three different types of convergent boundaries: Oceanic – Oceanic Oceanic – Continental Continental - Continental

Oceanic – Oceanic Plate Boundaries http://geology.com/nsta/convergent-boun

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Oceanic – Oceanic Convergent Boundary Normally one of the oceanic plates will

subduct below the other. The older plate is usually the one that gets

pushed down because it has a greater density. Eventually magma is formed because of the

increased pressure causing volcanoes to form over the top of the layer. Eventually the volcanoes will peak out of the

water and if they continue to grow the will form island chains. Ex. Japan

Oceanic – Oceanic Plate Boundary

Continental – Oceanic Plate Boundaries “Mt. Adams” http://geology.com/nsta/convergent-boun

dary-oceanic-continental.gif

Continental – Oceanic Plate Boundaries When the two plates collide the less

dense continental plate will rise up on top of the more dense oceanic plate. The subducted plate will become molten

due to the increase in temperatures. The magma will then rise because it is less

dense than the mantle that is surrounding it. As the magma rise it will cause volcanic and

earthquake activity.

Continental – Oceanic Plate Boundaries

Continental – Continental Plate Boundaries http://geology.com/nsta/convergent-boun

dary.gif

Continental – Continental Plate Boundaries The process in which two land masses

collide together. Normally the landmass that is the least dense will subduct only slightly below the other. Mountains will form because the two

colliding plates are very light in comparison to the mantle.

Divergent Plate Boundaries

Divergent Boundary – the boundary between two tectonic plates that are moving away from each other. New Sea floor forms at divergent

boundaries. Mid-ocean ridges is the most common type

of divergent boundary.

Divergent Plate Boundaries

Transform Boundaries

Transform Boundary – The Boundary between tectonic plates that are sliding past each other.

Ex. San Andreas Fault in California. One of the few faults that can be visibly

seen. One of the major causes of Earthquakes.

Output: Pushing and Pulling Mountains Draw an example of the five different

plate boundaries. Label and describe what happens at

each different plate boundary.

Transform Plate Boundaries

Plate Summary

Possible Causes of Tectonic Plate Motion Asthenosphere flows very slowly. This movement occurs because of the

change in density within the asthenosphere. Density changes because of the outward

flow of energy within the Earth. Hot rock expands and rises.(Less Dense) Cool rock contracts and sinks. (More Dense)

Possible Causes of Tectonic Plate Motion

Tracking Tectonic Plate Motion Tectonic plates move roughly 5cm per

year. The rate is so slow that it cannot be seen

nor felt except during an Earthquake. Plate movement is tracked by GPS.