Earth and Environment Atlas

How The Planet Works
Processes

Seafloor Spreading

Citation Formats

General Reference

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The formation of new oceanic crust along divergent mid ocean ridges as plates pull apart, balancing the crust lost to subduction elsewhere in a planet-wide conveyor belt. Harry Hess proposed the mechanism in 1962, and its confirmation in the mid to late 1960s is what turned continental drift from a rejected idea into accepted plate tectonics.

Facts
Timescale
Ongoing, centimeters per year 1
Driving Force
Upwelling magma at mid-ocean ridges, where new oceanic crust forms and spreads apart as plates diverge. 2
Resulting Feature
Produces new oceanic crust in symmetric magnetic stripes on either side of a mid-ocean ridge, the key evidence for plate tectonics. 2
Significance
Seafloor spreading, confirmed by seafloor mapping and paleomagnetic stripe evidence, resolved the missing mechanism that had stalled acceptance of continental drift for decades. 2
Cross-Tradition Connections

Associated With

Decompression melting of upwelling asthenosphere is the source of mid-ocean ridge basalt.

Marine magnetic anomalies gave clear geophysical evidence for seafloor spreading.

Rifting, Processes

Major rifts run along the central axis of most mid-ocean ridges, where new oceanic crust forms.

The zigzag pattern of oceanic transforms results from oblique seafloor spreading along divergent boundaries.

In Discipline

Precursor To

Confirmation of seafloor spreading in the 1960s is what turned continental drift into accepted plate tectonics.

Sources
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