Do Now: On what page of the ESRT can you find information about plate boundaries?

Turn and Talk: With your partner, what are the types of plate boundaries. Where can you find them?

Learning Objective: I will be able to explain the theory of plate tectonics.

Success Criteria: I can use the ESRT to identify tectonic plates. I can explain how convection currents drive plate motion. I can explain why oceanic and continental crusts have different densities.

What is the Theory of Continental Drift?

What is the Theory of Continental Drift? The continents were once a super-continent called Pangea the continents are plowing through the ocean floors---most people didn’t believe this

What evidence supports this theory? Africa & South America look like they fit together similar fossils, rocks, and glacial striations

Who came up with the theory of continental drift? New theory on how the plates move…

Quick Review:

What is the Theory of Plate Tectonics? Earth's crust is made up of plates that ride on top of the asthenosphere The plates move due to convection currents in the mantle

What evidence supports this theory? distribution of earthquakes and volcanoes sea-floor spreading

On what page of the ESRT can we find information on the layers of the Earth?

How do oceanic and continental crust compare with regard to thickness and density? (ESRTs pg 10) thickness high low thin thick

continental crust oceanic crust What are the primary rocks which make up the continental and oceanic crusts? continental crust oceanic crust Low-density, light- colored, coarse- grained, felsic, igneous rock High density, dark- colored, fine-grained, mafic igneous rock granite basalt

What types of rocks are granite and basalt?

Group Activity: Read A-Loud: Theory of plate tectonics Answer the questions with your group.

Summary: How do scientists locate plate boundaries?

What are these types of plate boundaries? What are the key characteristics for each? Give an example of where each can be found.

oceanic-continental convergent boundary trenches, volcanoes, deep earthquakes Peru-Chile Trench

continental-continental convergent boundary mountain building Himalayas

transform fault slide past one another shallow earthquakes San Andreas Fault

divergent plate boundary new crust is made Mid-Atlantic Ridge

On to the next question...

What happens to the age of oceanic crust as distance increases from a ridge?

same pattern on opposite sides of the ridge proves sea-floor spreading Explain how magnetic data can be used to show that oceanic crust is diverging at ridges. Use the diagram below to help explain your answer. as new crust is made at ridges, the ferrous minerals (Fe) align according to where the magnetic poles are located same pattern on opposite sides of the ridge proves sea-floor spreading