Continental Drift
Key Terms
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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.