Plate Tectonics

Objectives:

    1.    Discuss some of the evidence that Alfred Wegener used to support his idea of continental drift.

    2.    Describe the theory of plate tectonics.

    3.    List the evidence and describe the evidence used to support the plate tectonics theory.

    4.    Discuss mantle convection as a possible cause of plate movements

    5.    Compare and contrast the push-pull model.

Key Terms:

        plate tectonics        continental drift        mid-ocean ridge        mantle convection        ridge push        slab pull

Notes: (8-1 & 8-2)

The Earth's surface is constantly changing.  As new land is produced at the mid-Atlantic ridge, old land is being subducted at our continental borders.  The movement of land is explained with the acceptance of the presence of many lithospheric plates that continually float and reposition atop of the semi-solid asthenosphere.  The theory that explains this process is called plate tectonics.  The theory is not a new one.  As early as the1500s map makers were beginning to notice that the individual continents fit together like pieces of a jigsaw puzzle.  It wasn't until 1912 that Alfred Wegener first proposed an acceptable hypothesis (continental drift) as an explanation.

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 Wegener’s continental drift hypothesis:

    The theory of continental drift simply stated that continents drifted from one location to another over time.  Wegener noticed that the coasts of South America and Africa seemed to fit together like a puzzle.  Upon further investigation he noticed the following clues that he used to support his hypothesis. 

 

Plate Tectonics

In the 1950s & 1960s technology had sufficiently advanced and the theory of plate tectonics became more widely accepted.  

Driving Mechanisms of Plate Tectonics

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Evidence That Supports Plate Tectonics