Seafloor Spreading

Seafloor spreading can be a difficult concept for middle school students to grasp. These resources should help make the concept comprehensible through the use of images and animations and by acknowledging the concept’s larger context of plate tectonics.

Harry Hess: One of the Discoverers of Seafloor Spreading
This detailed biography shows how Hess’s skills enabled him to contribute to the scientific knowledge base of seafloor spreading and how his observations, models and predictions support the theory of plate tectonics.

The Distance Between Us and Them: Seafloor Spreading in the Atlantic Ocean
In this activity, students gain an understanding of how geologists determine rates of seafloor spreading. Using a strip map of the North Atlantic seafloor, students measure distances and note the ages of the strips of basalt. They also gain experience in applying mathematical concepts such as calculation and use of velocities and conversion from one set of units to another.

Seafloor Spreading
This page, part of the NeMO project, provides a concise explanation and a graphic representation of seafloor spreading and its relationship to divergent tectonic plates. Related links at the bottom of page include a link to mid-ocean trenches.

This Dynamic Earth: The Story of Plate Tectonics
This free, online booklet, containing photos and graphic illustrations, puts the idea of seafloor spreading in the larger context of plate tectonics.

Interactive Animation of Seafloor Spreading and Magnetic Field Reversals
Earth’s magnetic field reverses itself from time to time; North becomes South and South becomes North. Rocks on the seafloor on either side of a mid-ocean spreading ridge preserve a record of the Earth’s magnetic field over time. This page also shows how distance from the ridge is related to age or time.

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