Seafloor Reversal

Changing frequency over time.

Seafloor reversal.

Seafloor spreading and polar reversal. The current time scale contains 184 polarity intervals in the last 83 million years and therefore 183 reversals. The rate of reversals in the earth s magnetic field has varied widely over time. Through analysis of seafloor magnetic anomalies and dating of reversal sequences on land paleomagnetists have been developing a geomagnetic polarity time scale gpts.

This was sufficient to allow computing of spreading rates over the last 700 000 years on many mid ocean. The minerals contained in the rocks are oriented opposite to the magnetic field. Early in the history of investigating the hypothesis only a short record of geomagnetic field reversals was available for studies of rocks on land. The hypothesis links seafloor spreading and geomagnetic reversals in a powerful manner with each expanding knowledge of the other.

Explains how magnetic polarity frozen into seafloor basalts reveals evidence for the creation of new seafloor at mid ocean ridges. In the 20th century the magnetic survey was conducted in the mid ocean ridge in order to investigate evidence of sea floor spreading. How magnetic reversals on the seafloor provide evidence for seafloor spreading. Most basalt magmas contain abundant molten iron.

Their crystals are pulled into alignment by the earth s magnetic field just like a compass needle is pulled towards magnetic north. As magma starts to harden into rock iron rich minerals solidify first.