Do Now: Video Clip While watching the following clip answer the following: What did Harry Hess discover? What did he call his discovery?

Turn and Talk: Who’s evidence is stronger, Alfred Wegner or Harry Hess? Explain. Write your answer on the white board and turn it in. 5 points on tomorrow’s quiz.

Learning Objective: I can explain how sea floor spreading explains continental drift.

Success Criteria: I can describe the process of sea floor spreading. I can support continental drift using sea floor spreading. I can explain how pealeomagnetism supports sea floor spreading.

How does this movement at the mid-ocean ridge begin? At the mid-ocean ridge, molten material rises from the mantle and erupts. The molten material then spreads out, pushing older rock to both sides of the ridge.

Group Activity: Each group will present there section to the class. Everyone must take notes during the presentations. Answer the question being asked.

Three Types of Evidences: What types of evidence support the theory of sea-floor spreading? Three Types of Evidences: Evidence from Molten Material

How does magnetic stripes support the theory of Sea floor spreading? 2. Evidence from Magnetic Stripes

How the seafloor got it’s stripes!

Drilling Samples 3. Evidence from Drilling Samples Youngest rock was found in the center and older further away.

What is subduction? Subduction is the process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle.

Subduction

What is created where subduction occurs? The ocean floor plunges into deep underwater canyons called deep-ocean trenches. Deep Ocean Trench

How does this help explain Wagner’s idea of continental drift?

Why doesn’t the ocean floor keep getting wider? The Pacific Ocean is getting smaller and the Atlantic Ocean is getting bigger.