Seafloor Reversal

Early in the history of investigating the hypothesis only a short record of geomagnetic field reversals was available for studies of rocks on land.

Seafloor reversal.

Most basalt magmas contain abundant molten iron. Explains how magnetic polarity frozen into seafloor basalts reveals evidence for the creation of new seafloor at mid ocean ridges. Click create assignment to assign this modality to your lms. The minerals contained in the rocks are oriented opposite to the magnetic field.

Their crystals are pulled into alignment by the earth s magnetic field just like a compass needle is pulled towards magnetic north. The current time scale contains 184 polarity intervals in the last 83 million years and therefore 183 reversals. Changing frequency over time. Seafloor spreading and polar reversal.

This was sufficient to allow computing of spreading rates over the last 700 000 years on many mid ocean. How magnetic reversals on the seafloor provide evidence for seafloor spreading. The hypothesis links seafloor spreading and geomagnetic reversals in a powerful manner with each expanding knowledge of the other. What they discovered was the mid ocean ridge was actually a site where tectonic plates which are large pieces of the earth s crust were pulling apart from.

As magma starts to harden into rock iron rich minerals solidify first. The rate of reversals in the earth s magnetic field has varied widely over time.