1. EVIDENCE OF CONTINENTAL DRIFT - Similarities in coastlines of continents - same Fossils found on eastern S. America and west Africa - Rock type and age of coastal regions -Glacial debris

2. Earth’s Interior How do we study the earth’s interior? -Seismic waves -The direction and intensity of waves CHANGE as they pass through different materials -By studying these changes scientists can infer the structure of the Earth’s interior

3. Earth’s interior continued…. Refraction- bending of a wave caused by a change in speed as it travels from one material to another Discontinuity- boundary between 2 layers of materials with different densities Shadow zones- location where NO seismic waves are detected

4. Earth Layers OUTSIDE TO INSIDE -crust -mantle -outer core -inner core

5. EARTH’S 2 CRUST TYPES - Continental crust- CONTINENTAL LANDMASS - Oceanic crust- OCEAN FLOOR more dense than continental

6. Earth’s Layers continued…. Lithosphere (lithos means rock) - occurs in crust and UPPERMOST mantle - solid rock - made of tectonic plates You tube video Earth's Interior - Seismic Evidence Explanation

7. Asthenosphere (magma) - in UPPER mantle and is plastic (liquid) The lithosphere floats on the asthenosphere like wood floating on water

8. CAUSES OF PLATE MOTION -Convection –transfer of heat through heated material -As a material is heated it becomes less dense and rises, as it rises it cools and becomes more dense and sinks -This is referred to as a CONVECTION CURRENT -This occurs in the asthenosphere