The Earth’s Crust in Motion… Plate Tectonics The Earth’s Crust in Motion…

Earth’s Structure Crust Mantle Inner Core Core Outer Core Lithosphere (about 3 - 43 miles thick) Mantle (about 1,790 miles thick) Inner Core (about 750 miles thick) Core Outer Core (about 1,410 miles thick) Using a laser pointer, briefly highlight and describe the layers of the earth’s interior. Also highlight the fact that the earth has oceanic and continental crust. Lithosphere (crust and upper mantle) broken into tectonic plates

The Theory of Plate Tectonics In 1910 Alfred Wegener begins to wonder… What’s the relationship between the continents? Perhaps all these pieces used to be connected. He develops the theory of Continental Drift - the belief that continents are slowing moving over the Earth’s surface 300 million years ago… Ask the students to look closely at the map. “What does it remind you of?” When ‘puzzle’ is suggested introduce first line. Click on the image of Wegener for the hyperlink to USGS while discussing who he was. Continue to discuss Wegener’s theory and introduce continental drift definition.

Pangea The Supercontinent Discuss the theory of Pangea and show animation (click on link). Tens of Millions of years!

How does it work? Plates – pieces of the lithosphere Plates fit closely together along cracks called Plate Boundaries Plate movement is caused by convection currents in the mantle Plates move at a rate of a few centimeters a year Explain that the lithosphere is broken into pieces called plates. The place where the pieces fit together are the boundaries. Using a laser pointer, explain the theory that plate movement is caused by convection currents in the mantle.

We live here Ask the students to look closely at the map. “What does it remind you of?” When ‘puzzle’ is suggested introduce first line. Click on the image of Wegener for the hyperlink to USGS while discussing who he was. Continue to discuss Wegener’s theory and introduce continental drift definition.

How Plates Move Divergent Convergent Transform Move away from each other Convergent Move toward Transform Slide past Define each term. Have the students as a class mimic the movement of divergent, convergent, and transform boundaries using their hands. Use the hyperlinks as visuals while discussing each type of plate boundary.

Divergent

Convergent

Transform

A Divergent B Convergent C Transform plates are moving apart new crust is created Magma is coming to the surface plates are coming together crust is returning to the mantle plates are slipping past each other crust is not created or destroyed

A Divergent B Convergent C Transform Continental crust  rift valley Oceanic crust  mid-ocean ridge 2 continental plates  mountain range Plates move against each other Stress builds up Stress is released earthquake 2 oceanic plates or oceanic + continental subduction

The Big Picture Remind students to look for their assigned boundaries and write down information to describe them.