1. RAP 1 What is the principle of all geologic change occurs suddenly? (Earth’s Story) 2.What types of fossils occur in hot dry places? (fossils) 3. Supercontinent is called __________ (Pangea)

2. Key Questions Plate Tectonics 1. What is seafloor spreading? 2. What is the theory of plate tectonics? 3. What are lithospheric plates? 4. What makes tectonic plates move? 5. What are convection currents?

3. What is seafloor spreading? 1. Seafloor spreading- the process by which new oceanic lithosphere is created and old is pulled down

4. What is plate tectonics? 2. Plate tectonics is the theory that the Earth’s lithosphere (crust) is divided into tectonic plates that move around on top of the asthenosphere (upper mantle)

5. What are tectonic plates? 3. Lithospheric plates are huge slabs of rocks that float on top of the asthenosphere.

8. 4. What makes tectonic plates move? 4. Plates move because of Heat and gravity Ridge Push Slab pull Convection Currents

9. 5. What are convection currents? 5. Convection Currents (warm materials rise and cool materials sink)

10. How Plates Move: Convection Currents When any fluid is heated there is a natural tendency for the hotter material to expand (thus making it less dense) and rise to the surface. At the surface it loses heat and travels sideways, eventually cooling, becoming more dense and sinking. The process repeats itself, with the fluid moving round and round in convection cells

11. . How Plates Move: Convection Currents Convection Currents