Seafloor Reversal

Most basalt magmas contain abundant molten iron.

Seafloor reversal.

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

The hypothesis links seafloor spreading and geomagnetic reversals in a powerful manner with each expanding knowledge of the other. By using the magnetometer the magnetic polarity will be shown through a timescale that contains the normal and a reverse polarity. How magnetic reversals on the seafloor provide evidence for seafloor spreading. Early in the history of investigating the hypothesis only a short record of geomagnetic field reversals was available for studies of rocks on land.

Their crystals are pulled into alignment by the earth s magnetic field just like a compass needle is pulled towards magnetic north. Seafloor spreading and polar reversal.