Seafloor Reversal

In the 20th century the magnetic survey was conducted in the mid ocean ridge in order to investigate evidence of sea floor spreading.

Seafloor reversal. As magma starts to harden into rock iron rich minerals solidify first. How magnetic reversals on the seafloor provide evidence for seafloor spreading. 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. Most basalt magmas contain abundant molten iron.

The current time scale contains 184 polarity intervals in the last 83 million years and therefore 183 reversals. Click create assignment to assign this modality to your lms. Explains how magnetic polarity frozen into seafloor basalts reveals evidence for the creation of new seafloor at mid ocean ridges. The rate of reversals in the earth s magnetic field has varied widely over time.

Changing frequency 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. By using the magnetometer the magnetic polarity will be shown through a timescale that contains the normal and a reverse polarity. Early in the history of investigating the hypothesis only a short record of geomagnetic field reversals was available for studies of rocks on land.

This was sufficient to allow computing of spreading rates over the last 700 000 years on many mid ocean. Seafloor spreading and polar reversal.