What is “magnetic reversal?”

The Energy Dilemma: Seismic Evidence for Earth’s
Internal Structure Reveals a Power Source
During the early 1960s, seismologists studying earthquake seismic waves
detected the layer configuration of the Earth’s crust, mantle, outer and inner
core. They found that the crust and the upper most portion of the mantle
actually acted together as a single brittle layer. They called this the lithosphere.
More importantly, they discovered that under the lithosphere, a several
hundred mile thick portion there existed a layer that of rock with fluid-like
properties. They called this layer the asthenosphere. Although the rocks were
solid, they acted as though they were plastic.
This plastic layer became
the key to explaining how
continents moved.