No ocean crust dates back further than that, so earlier reconstructions are more difficult.

The ocean crust would in effect act as a kind of giant tape recorder of magnetic anomalies over time.

This suggests that the lower part of the ocean crust contains a substantial magnetic signature.

Ocean crust consists of basic igneous rock, containing significant amounts of magnetite.

This incipient ocean crust remains locked to the continental margin when the ocean basin closes, emplacing the incipient ocean crust into the collision zone.