Continental Drift Key Terms • • • • Continental Drift Mid-ocean ridge Sea-floor spreading Paleomagnetism Wegener’s Hypothesis • Hypothesized continents once formed part of a single landmass called a supercontinent. Science Needs Evidence How do each of these strengthen the argument of Continental Drift? • Fossil evidence • Evidence from Rock Formations • Climatic Evidence • Mechanisms that cause movement • Mid-ocean ridges • Sea-floor spreading Growth of the Atlantic Ocean • The Atlantic ocean is spreading at a rate of 1 to 2 cm per year. How many years will it take for the sea floor of the Atlantic Ocean to spread 1 km? Paleomagnetism • Research and Explain each of the following: Please use diagrams with your explainations. • Magnetic Reversals • Magnetic Symmetry Prediction • If the plates of the world are moving at an average rate of 2 cm per year, how many kilometers will the plates move in 2.5 X 108 years? • Produce a map of the Earth and what it will look like 2.5 X 108 years from present. Map should include BOTH present and future locations of the continents and oceans. • Use page 5 of your ESRT to determine current directional movement for each plate. Questions • 1. Describe the observation that first led to Wegener’s hypothesis of continental drift. • 2. Explain how scientists know that Earth’s magnetic poles have reversed many times during Earth’s history. • 3. Identify how magnetic symmetry can be used as evidence of sea-floor spreading. • 4. Explain how scientists date sea-floor rocks. Questions • 5. How does evidence that rocks farther from a ridge are older than rocks closer to the ridge support the idea of spreading? • 6. Use the following terms to create a concept map: continental drift, paleomagnetism, fossils, climate, sea-floor spreading, geologic evidence, supercontinent, and mid-ocean ridge.