Download Sea Floor Spreading

Sea Floor Spreading Evidence
Sea Floor Spreading
Sea Floor Spreading Evidence
Evidence:
Magnetic evidence of sea floor spreading.
Periodic switches in Earth's magnetic polarity stripes are symmetric with respect to the mid
ocean ridges.
Sea Floor Spreading Evidence
Age of the Ocean Floor
Ocean floor gets older as you move away from MOR's
ex. ocean floor east of east Pacific rise older than 40 million years old has already
subducted while ocean floor in the NW Pacific is about 180 years old.
Sea Floor Spreading Evidence
Heat Flow
The heat from Earth's interior is released to the surface as heat flow. Current models
indicate that heat moves to the surface with magma in convective motion. Most of the
heat is carried to regions of mid-ocean ridges.
Heat flow measurements at ocean ridges can be 8X greater than other parts of Earth's
crust. Heat flow at deep sea trenches (subduction zones) can be 1/10 of the average.
Sea Floor Spreading Evidence
Worldwide Earthquakes
Most large earthquakes occur along ocean trenches, reflecting the amount of energy released
during subduction. Other earthquakes occur at mid-ocean ridges, reflecting the energy
released during sea floor spreading.