1. Coach Williams Room 310B

2.  Plate Tectonics

3. Objectives  Describe one piece of early evidence that led people to suggest the Earth’s continents my have once been joined.  Discuss evidence of continental drift  Explain why continental drift was not accepted when it was first proposed.

4.  Fit of continents across Atlantic Ocean  Gondwanaland: southern continents

6.  Theory that Earth’s continents were once joined.  Continents had slowly drifted apart  Pangaea: “all the Earth”

7.  Rocks: similar rocks  Fossils: animal/plant remains  Ancient Climate: coal in Antarctica

8.  2 Reasons the theory was rejected ◦ 1) What forces could cause them to move? ◦ 2) How could continents move and not shatter?

9. Objectives ◦ Summarize the evidence that led to the discovery of seafloor spreading. ◦ Explain the significance of magnetic patterns on the seafloor. ◦ Explain the process of seafloor spreading.

10.  Sonar- sound waves to determine depth  Magnetometer- detects changes in magnetic fields  Map the ocean floor

11.  Mountain ranges (ridges), trenches  Earthquakes & volcanoes

13.  Varying ages of rocks: pattern ◦ Younger rocks near ridges ◦ Older rocks farther away  Sediments ◦ Thinner than continental crust ◦ Thickness increased farther away from ridge

14.  Paleomagnetism: study of magnetic record ◦ Basalt(Iron) = compass needle  Magnetic reversal: change in Earth’s magnetic field  Magnetic symmetry: matching strips on each side of ridge

15.  New crust created at ridges  Crust is destroyed at trenches  Magma comes out of ridges  New rock pushes crust outward  Provided evidence for continental drift

19. Objectives:  Explain the theory of plate tectonics  Compare/contrast the three types of plate boundaries and the features associated with each.

20.  Earth’s crust: large slabs called plates  Major and smaller plates

22.  Plate boundaries: where plates meet ◦ Divergent ◦ Convergent ◦ Transform

25.  Plates moving apart  Most on ocean ridges  Rift valley: narrow valley along divergent boundary

26.  Plates moving together ◦ Oceanic crust – oceanic crust: volcanoes ◦ Oceanic crust – continental crust: volcanoes ◦ Continental crust – continental crust: mountains  Subduction- one plate goes below the other

28.  Plates slide horizontally

29. Objectives:  Explain the process of convection  Summarize how convection in the mantle is related to the movements of tectonic plates  Compare/contrast the processes of ridge push and slab pull

30.  Convection: movement due to temperature differences  Mantle has convection currents  Currents move plates  Ridge push- weight of ridge pushes plate down  Slab pull- weight of plate pulls plate down