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In the book of life, the answers aren't in the back. - Charlie Brown -

Explore the fascinating world of tectonic plates and continental drift. Discover how the Earth's surface is fractured into plates and learn about the various types of plate boundaries and their effects. Delve into the causes of earthquakes, volcanoes and the formation of mountain ranges.

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In the book of life, the answers aren't in the back. - Charlie Brown -

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  1. In the book of life, the answers aren't in the back. - Charlie Brown -

  2. TECTONIC PLATES

  3. THE EARTH’S SURFACE IS FRACTURED INTO A SERIES OF PLATES THAT RIDE ON THE SOFTER, PLASTIC MANTEL (ASTENOSPHERE). BECAUSE OF THE THERMAL CONVECTION CURRENTS IN THE ASTENOSPHERE, THESE PLATES MOVE RELATIVE TO EACH OTHER. THIS MOVEMENT IS CALLED CONTINENTAL DRIFT. THIS IDEA WAS FIRST PROPOSED BY WEGENER IN 1912.

  4. WEGENER NOTICED THAT SOUTH AMERICA AND AFRICA FIT TOGETHER SORT OF LIKE THE PIECES IN A JIGSAW PUZZLE. PEOPLE THOUGHT HE WAS CRAZY.

  5. IT WAS NOT UNTIL THE 1950’S AND 1960’S THAT ENOUGH SCIENTIFIC EVIDENCE STARTED COMING IN TO PROVE HIM RIGHT. PART OF THE EVIDENCE CAME FROM MARINE SCIENTISTS WHO WERE SCANNING THE OCEAN FLOOR LOOKING AT ITS MAGNETIC PROPERTIES. THEY NOTICED THAT AS THEY MOVED AWAY FROM THE MID OCEAN RIDGE, THE MAGNETIC PROPERTIES KEPT CHANGING.

  6. THIS WAS EVIDENCE OF SEA FLOOR SPREADING. AS THE CONTINENTS SEPARATED, THE FOLLOWING SEQUENCE OCCURRED.

  7. THIS IS WHAT IS HAPPENING ALONG THE MID-ATLANTIC RIDGE. THE NORTH AMERICAN PLATE IS MOVING AWAY FROM THE EURASIAN PLATE, AND NEW OCEAN CRUST IS BEING FORMED. THIS IS CALLED A DIVERGENT PLATE BOUNDARY.

  8. THIS BOUNDARY CUTS RIGHT THROUGH THE ISLAND OF ICELAND.

  9. AERIAL VIEW OF THE FAULT IN ICELAND.

  10. THE SAME THING IS HAPPENING IN AFRICA IN THE RIFT VALLEY.

  11. ALONG DIVERGENT PLATE BOUNDARIES, NEW CRUST IS BEING CREATED. THE EARTH’S SIZE IS NOT CHANGING, AND HASN’T CHANGED IN ITS 4.5 BILLION YEAR EXISTENCE. IF THIS IS THE CASE, WHAT ELSE MUST BE HAPPENING?

  12. IF NEW CRUST IS BEING CREATED IN ONE PART OF THE WORLD, CRUST IS BEING DESTROYED IN OTHER PARTS OF THE WORLD. THIS OCCURS ALONG CONVERGENT PLATE BOUNDARIES. ONE TYPE OF CONVERGENT BOUNDARY OCCURS WHEN HEAVIER OCEAN CRUST PUSHES UNDER LIGHTER CONTINENTAL CRUST.

  13. ALONG THE COAST OF SOUTH AMERICA, THE NAZCA PLATE IS SLIDING UNDER THE SOUTH AMERICAN PLATE. THIS PROCESS IS CAUSING UPLIFTING AND IS CREATING THE ANDES MOUNTAINS. SUBDUCTION IS THE CAUSE OF EARTHQUAKES AND VOLCANOES. AS ONE PLATE MOVES UNDER ANOTHER, IT WILL SOMETIMES STICK UNTIL FORCES BECOME GREAT ENOUGH TO RELEASE IT. WHEN IT IS RELEASED, AN EARTHQUAKE OCCURS.

  14. OCEANIC-OCEANIC CONVERGENCE CAN ALSO OCCUR. PARTIAL MELTING OF THE SUBDUCTING PLATE CAN RESULT IN MAGMA THAT FORMS VOLCANOES. OVER TIME, THESE CAN BUILD UP TO THE SURFACE AND FORM ISLANDS.

  15. CONTINENTAL-CONTINENTAL CONVERGENCE CAN RESULT IN THE FORMATION OF HIGH MOUNTAIN RANGES. THIS HAPPENED WHEN THE INDIAN CONTINENT COLLIDED WITH THE EURASIAN CONTINENT.

  16. TRANSFOM BOUNDARIES RESULT WHEN TWO PLATES SLIDE PAST EACH OTHER. THIS HAPPENS ALONG THE SAN ANDREAS FAULT. THE NORTH AMERICAN PLATE AND THE PACIFIC PLATE ARE SLIDING PAST EACH OTHER. THIS CAN RESULT IN EARTHQUAKES.

  17. http://www.iris.edu/seismon/

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