1. Plate Tectonics Subtitle

2. First, let’s back up… ▪ What’s continental drift?  The movement of the CONTINENTS over a long period of time  But why are they moving??? ▪ Continents move because they are driven by convection currents in the mantle  Why are there convection currents in the mantle?  The Earth’s core heats up the mantle by conduction and radiation  This causes the bottom of the mantle to heat up and become less dense  The less dense material “floats” to the top, and as it cools becomes more dense  Now that it is more dense it wants to sink back down  …oh, you mean it makes a convection current!!

3. First, let’s back up… ▪ So if the continents are moving…what are they moving on? ▪ The continents sit on Plates  Plate – A broken chunk of the lithosphere that moves as it is affected by convection currents. ▪ The Plates are the things that are actually moving…the continents are just along for the ride.

4. THE THEORY OF PLATE TECTONICS ▪ Scientific Theory vs. Scientific Fact  Theory – A hypothesis that is widely excepted and is supported by many different experiments  Fact – A verifiable observation that is the same everywhere. It has been proven over and over again. Theory’s help explain a fact.

5. THE THEORY OF PLATE TECTONICS ▪ Theory of Plate Tectonics – states that pieces of the Earth’s Lithosphere are in slow, constant motion, driven by convection currents in the mantle.  It explains the formation, movement, and subduction of the Earth’s plates. ▪ If this is a theory…what FACT does it help explain? – Continental Drift!

6. Plate Boundaries… ▪ Because the plates are moving in different directions, there are 3 major different possible interactions between the plates. 1.Divergent Boundaries – Plates separate. Results in a Rift Valley 1.Convergent Boundaries – Plate collide. Results in: a)Mountains OR b)Volcanoes and trenches 2.Transform Boundaries – Plates Scrape each other. Results in earthquakes

7. Divergent Boundaries OR

8. Convergent Boundaries ▪ Oceanic – Oceanic Collision

9. Convergent Boundaries ▪ Oceanic – Continental Collision

10. Convergent Boundaries ▪ Continental– Continental Collision

11. Transform Boundaries

12. Apply it The San Andreas Fault is a plate boundary between the Pacific Plate and the North American Plate. What type of boundary is it? What might happen to California in a few million years?