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.