The Theory of Sea Floor Spreading
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Sea Floor Spreading
• Harry Hess (1960)
• as the ocean floor spreads apart, new crust material rises from the mantle and creates new sea floor to fill the “hole.”
HESS (1960)• Sea floor spreading • Continents were moving (as Wegener had proposed)• Evidence1.2.3.
1. The discovery of the Mid-ocean Ridge
• Scientists mapped 47,000 miles of underwater volcanic ridges by using sonar
Map of Mid-ocean Ridges
2. Ocean floor shows Magnetic Poles reversing
3. Ocean floor samples—older crust is further away from ridges
