Name _______________________
Wegener’s Continental Drift Hypothesis

__________________________________ is the hypothesis that states that continents once
formed a single landmass, broke up, and drifted to their present locations.
• Scientist Alfred __________________ developed the hypothesis in the early 1900s.
The Breakup of Pangaea
•Wegener theorized that all of the present continents were once joined in a ______________,
huge continent he called _____________________.
• Pangaea is Greek for “_________________.”
• Pangaea existed about 225 ____________________ years ago.
•Evidence Wegener used to support his theory of continental drift: ________________, fossils,
__________________, and __________________fit.
•Wegener had tons of evidence for continental ________ but he could not provide an
explanation for the ________ that moves continents. From 1920-1960, most people paid very
little attention to his theory because he could not explain how the continents moved.
But then some new evidence was discovered…..
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Seafloor Spreading
•__________ to support the continental drift hypothesis comes from sea-floor spreading.
• Sea-floor spreading is the _______________ by which ___________ oceanic lithosphere
forms as magma rises toward the surface and solidifies.
•Mid-Ocean Ridges and Sea-Floor Spreading: _____________________ are underwater
mountain chains.
• These mid-ocean ridges are the places where sea-floor spreading takes place and new oceanic
lithosphere is created.