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.